The Basics of Aeromodelling

629.1331 Sm3e lAeromodelling VIC S M EED ALLEN COUNTY PUBLIC LIBRARY FORT WAYNE, INDIANA 46802 You may return this book to any location of the Allen County Public Library. DEMCO ;7 THE The eas AEROMD BASICS OF. . . Aeromodelling Vic Smeed X NEXUS SPECIAL INTERESTS \ \, X m u'lir <^tr&et ^^£51 900 V^ebster Ltd PO Box 2270 45801^^' ^270 IN FortWayne. No port of this work may be reproduced in any form..Public Library Nexus Special Interests Nexus House Boundary Way Hemel Hempstead Herts Allpn County '^"^T. All rights Design and typesetting by The Studio. HP2 7ST England First © published 1995 Vic Smeed 1995 ISBN 1-85486-113-1 reserved. Glasgow . photograph. Exeter Printed and bound in Great Britain by Bell & Bain Ltd. by print. microfilm or any other means without written permission from the publisher. Contents Introduction 1 CHAPTER ONE About models CHAPTER TWO Tools 2 and materials 13 CHAPTER THREE Paper and chuck gliders 20 CHAPTER FOUR Traditional construction 26 CHAPTER FIVE Covering and finishing 36 CHAPTER SIX Trimming and 41 flying CHAPTER SEVEN Thumbelina 48 CHAPTER EIGHT Radio control 60 Glossary 64 . . . . . series Model Gliders Chas Gardiner Radio Control Model Boats Radio Control Model Cars Glynn Guest Alan Harman .Other titles in this The Basics of The Basics of The Basics of . . . . . The number of people in the aerospace industry. well field! — . On the other hand. However. interestingly. There ore excellent from which it is is what is. They all and a simple distance competition created a great deal of fun and excitement. or plans simple to build. not to mention knowledge.a gap which it is hoped this able to build or it is book will go some way Building models to fly to fill.gliders. From paper to simple balsa chuck gliders is not a big step.a lot of enjoyment. this is to the fact that a totally un- suitable kitted model was purchased. usually due fly their first attempt. their because of disappointment at not being numbers are continually growing. and there no certainly taking kits approach. see you on the flying If it succeeds. You could actually buy ready-to-fly rubber models in the 880s! Hundreds of modellers still prefer freeflight models . forgetting (or not realising) that models were flying for almost a century before off-the-shelf radio equip- ment became available. but one that can lead on to a lifelong hobby or even wider horizons. some years since a book was available setting out the groundwork of successful model building and flying in relatively simple terms . for beginners. newcomers off on the whichever type of model they cover every aspect This one seeks right foot. now it is the incurred by commonsense such a vast. Aeromodelling is faceted pursuit that to of face loss after all. who started from on interest in building models is really quite remarkable. need not be enor- mously expensive . rubber or enginepowered designs . every lad made a paper glider. At a recent talk to a Cub Scouts troop. and. many in high positions. there are many who become but do interested not progress to flying with radio.or control-line models 1 each boy standing in turn on a sturdy table to launch his model. flew. manyvirtually impossible in detail in one book.Introduction Nowadays most of the general public to think that it's if seem a model aeroplane it must be radio controlled. will to set ultimately favour. can be obtained with a couple of sheets of ordinary copy or typing paper and a length of kebab skewer. In the years following World War 2 there was another explosion of interest leading to introductions and developments which have brought aeromodelling to its presentday levels. from about 1908. the da Vinci sketches of possible aircraft are v/ell knov/n. Progress was very slow for some twenty years. an occasional petrol engine. but the earliest evidence of fixed- wing to Sir opposed to balloons) refers George Cayley's experiments around flight (as 1800. although with some steam. often at considerable expense. national regulatory bodies were formed in several countries and the foundations of club movements and international competitions were laid. steps which had been experimented with but not pursued in England in 1911 and 1 924. Few engines were seen in Britain or Europe but towline gliders were developed and. during the war years. of course. but there are nostalgia classes for later dates and an old-timer category covering vintage machine the early 1930s. however. so much so that modellers have in the vast majority become vintage of enthusiasts order to put the fun element back into flying. There are vague references to 'artificial doves' and similar early in manuscripts and. Most of the progress relates to high performance aspects of flying with the introduction of high-tech materials and techniques. model flying for pleasure dates back to the rubber-powered Penaud models sold ready-to-fly in quite considerable quantities the Paris area in the 1880s. the models being largely constructed from spruce. most modellers associated simplicity designs.) petrol engines duced. Organised competitions date from around 1905-6. The US cut-off is 1 942 in general. but the real popularity of building and flying only began in model In the 1930s. Average aeromodellers are likely to choose a design which attracts them. for while there are vintage fliers who abide by quite ensure that their models are strict the originals. compressed air and CO2 engines and even.CHAPTER ONE About models Model flying pre-dated full-size aeroplanes by a century. covered with silk or fine linen and powered mostly by rubber. Rubber was still the normal motive power although commercial miniature (lOcc or 60 appeared in the USA in 1934 and radio control about three years later. There are good arguments for choosing a kit model. following the introduction of balsa coincident with a wove of airmindedness which swept the world. in. the increasing losses of flyaway models arising from the wider use of petrol (gas) engines led to tethered flying which developed into control-line flying. it must have been published or kitted prior to that date. birch and bamboo. the cut-off date for a is December 1950.e. small compression-ignition motors were introcu. Models played a large part in the development of flight and still contribute to research and testing. In with rules to built exactly as just seek the vintage-style England. especially for someone inexperienced or without a good model shop within easy reach. but a great deal can be learned from very simple models that anyone can make and. The term vintage is used model loosely here. there are designs in magazines and books which built far more cheaply than the cost . and which is straightforward and not too expensive to build. In the US. for very little published can be extra trouble. Model design virtually stagnated from around 1910 to the late 1920s but mode rapid strides in the 1930s. i. loop and and. which is connected to the model's elevators by a pushrod and horn.free flight. Thus ment of the handle moves the the move- bellcrank. always engine engine attached handle held by the flier and thus flies round in a circle (actually within a hemisphere) with the flier turning continually to face the model. before delving too deeply into construction categorise tfie let us various types of models. (27m) for a large and powerful one. MODEL CLASSES Basically. if fitted.they are only used sense to the elevators and smoother and tighter on stunt models. . sometimes flaps are fitted to the wing trailing edge and a second pushrod operates these. At the model end.1 Bellcrank Pushrod Elevator handle. As the model flies round. Simple. (5m) for a very small model to perhaps 90ft. Each group subdivides with probably the simplest being control Control-line models powered by a glowplug or or. the control wires are attached to leadto a out wires permanently fitted to the model and secured to a bellcrank. However.and of these. The flaps. free flight (F/F) is the most diverse. slightly easier to Fig. if it perform horizontal or vertical figure eights. work in the opposite make manoeuvres . control line and radio control . there are three main groups of models . The model by two wires is line. In high! of an equivalent kit. (say 210 mj platform.he con make it climb and dive has enough power.ABOUT MODELS A competition rubber model taking off from a specially-built 40 seconds it will be perhaps 700 ft. use fishing light models con line for the control lines instead and line length can be anything from around 15ft. 1. Wire can be single strand or up to seven strand. the multistrand being of wire. by a petrol are diesel (ignition) or an electric motor. very rarely. the flier has control over it in pitch . of any one immediate division — glider or powered. There are various classes and offshoots if It a take-off than a hand launch. AEROMODELLINC classic style control-line stunt model 1994 World Champion combat winning model. the flier runs with the other end of the line. and keep the model low at first for maximum pull on the lines while you settle down. carrier and team racer broadly covers them. which should be level the engine's spraybar. Those on a flat field are thermal soarers. Right. taken on the bellcrank pivot bolt. each endeavouring to cut pieces off the other's streamer. Carrier involves a curved flight deck simulating an aircraft and includes points between the model's carrier for landing etc. . should feed from its outer rear corner. or a small pennant near the ring it off. and the model's balance point should be slightly in front of the bellcrank pivot. Again the tow ring slips since it . mostly American in origin and not frequently seen in Europe. speed. scale (which are self-descriptive). relying on flying into rising air for long flights. mouse racing etc. helping to keep type of aircraft but there is away. which if means that very short grass or a tarmac surface is needed. Team racers fly three in a circle on a limited tank size so that refuelling stops are needed in races. stunt. which must be secure. Radio-control models can be angle.. Points to remember are that the whole load of the model is such ately is may be immedi- and slowest laps.the elevator control should move stiff freely enough to drop under wind) control of the model lost. rat racing. A towline is a long line fitted with a ring which engages on the model's towhook. gliders may be functional or scale and flown either from a flat site or on a slope. Always take-off downwind. having been launched by towline or bungee. and the control must not be . since any breeze will help get the lines taut in the first half-lop. The fuel tank its own weight.sport. A beginner should start with a strong and easy-to-fly sport model. combat. Taking the simpler first. with wing flaps. slackening the line allows the ring to as Goodyear racing. especially the line tension slackens (because of difference fastest or the control lines taut. which makes with control simpler will easier to fly from the launcher is inexperienced. When it has climbed as high as possible and settled to a gliding the for with a and means that the nose tend to point outwards. but slip to pull nowadays plastic surgical tubing is used con stretch farther and catapults the model skyward in a much gentler and more consistent manner. flier Mervyn Jones There are several different sorts of C/L models . Combat models fly two in a circle trailing paper streamers. or winds it onto a winch drum (often a converted hand-drill) fast enough for the model to climb out of an assistant's hands. A bungee launch used to be carried out with elastic bungee cord.THE BASICS A OF . Aerotows are possible but not used in competition. roa reflects greoter heot control only the usually rudder function and may radio elevators. or in the nose. 1012ft. or is blown off the hook at the height of the launch. Different gliders perform better or worse depending on the wind strength. which is used to climb the model gently to a height of several hundred where there are good chances of feet. fighters etc. or functions could be flops. although elevators or ailerons and Gliders will usually fly well with a small engine mounted on a pylon above the wing. and some experts use on electrically driven winch.77m). looking very realistic fast flight!) and in flight lacking only (quite often (1. which ore scale models of full-size power aircraft slope soaring).5m). fly into thermal upcurrents but need not rely on them for long flights. Williams spans I5h. Three- use rudder/elevator/ two of these plus airbrakes. although a closed radio-operated towhook can be used. towhook and even a retracting take-off ailerons or More channels wheel. This Minimoa by C. in noise. The radio may more Thermal bubbles Factory. . The smallest are rarely less than 5ft. 5mm) being considered medium size. There is a class for hand-launched gliders. Sin. (3-3. of course. jets. rudder. escarpment or cliff and moke use of the vertical component of wind blowing onto the face of the hill. Slope soorers ore hand launched from near the top of a hill. The models can.ABOUT MODELS Radio-controlled scale gliders are ohen big. thrown javelin fashion and hoping to find rising currents at low level. (4. Radio gliders ore often quite large. It is possible to see PSS models (power-scale soorers. all built without engines for airliners. pylon where three or four models race around a course marked by ground pylons but this is for experts only and should only be tackled by really experienced fliers. There are also R/C helicopters. elevator and engine control. difficult of all as well as being expensive. provided the instruc- on charging the nickel-cadmium (nicad) cells are correctly followed. Electric-powered R/C models are becoming more and more popular and efficient and can do virtually everything a glow. Below.or Cadet by are often chosen for '4 1 scale aircraft 'A. Again. Some models use only ailerons instead of rudder for turn manoeuvres but most models designed as trainers have rudder. If models among to learn the most the challenge appeals to you. . American light planes of the 1930s. There racing. Specialist functions (bomb dropping. there are several books devoted to the subject and the wisest course to is ask your one or two for you study before choosing a model and public library to obtain radio. This is one of the beginner to learn a radio-controlled model. (or functions) called for: single channel is rudder only. but these tions are the most to fly. V3 and diesel-powered model can do. There is bound to be some blurring of classification since a scale model can well be fully aerobatic but flown for sport! It is possible to get some idea of a model's complexity by the number of radio channels scale. for a beginner a powered glider is an excellent way to learn to fly. elevator.THE BASICS OF. needle-valve adjustment etc. first R/C scale subjects. World War are popular R/C subjects at even V2 scale. Left. two means rudder/engine or rudder/elevator. four adds ailerons. falling into general categories - one in all of three sport. engine.) can add channels almost infinitely. like this Interstate Phillip Kent. parachutes. picking up thermal safest to fly approaches lift. five possibly retracting undercarriage or flaps and six both of these. AEROMODELLING . aerobatic or is an aspect of speed. trundling out a Sopwith Pup. three usually rudder. aileron trainers being considered the next step once the tyro has learned to fly. for a Powered R/C models come shapes and sizes. usually (1250-1 550mm) wingspan and capable of 7 minute or longer flights.ABOUT MODELS engines. small scale rubber models. four-stroke pressed down glowplug. Right. were the whole. There glow). air into to open rubber. pistachio scale. usually flown stantially Free-flight models offer enormous and only the main categories can be discussed here. competition classes are Wakefield.rubber. in. or specialised are Above. on simpler (and cheaper!). CO2. Rubber models are slightly handicapped by the absence of 'real' model shops. The lost. now so high-tech ence to a contest (or competition) model normally relates to a purely functional machine designed for maximum performance and often of a shape or appearance any country. diesel. (are) quicker . scale and contest. However.and each division breaks sport. uses pressed a high quality plastic bottle pumped by a pump to perhaps 7 bars (opprox. electric. there are mail-order sources which advertise most oeromodelling goods for those without a conventional stockist. available in kit form. also made sub- from plastic. may look simple but they are not suitable for first attempts. and 36in. The first division is power . a streamliner with parasol wing dating from 1938. com. span (450— 900mm) and the two major in sports 50-60 halls. flying a 30-36in. for a minute or so. 100 tyre psi) driving a piston engine. (750-900m) model. Vintage competitions attract vastly greater entries Categories which are currently relatively minor province of only a handful in many countries because pre-1950 models were. petrol (gas) that it is the in rubber. span peanut scale and Sin. glider. Types range from 13in. are competitions for scale models but refer- (1250mm). so not everyone can easily reach a shop selling rubber strip or ready-made propellers. four-strokes (seen quite normally in R/C models but not in F/F) and comair. These elegant models are reproduced by keen vintage builders worldwide and are rewarding to build and fly. in modern form. (750mm) or so and limited to 80 or lOOgms of quite strange to a newcomer. around 30in. 48-50in. internal combustion voriety (petrol or spark ignition. and Coupe d'Hiver. Most sport models ore between 18in. at Most beginners make the mistake of average modeller. The motor length is often as much as 1 . This is then doubled etc. Incidentally. up to towline models usually standing of natural air limited (for competition) to a maximum of The Achilles is an excellent first choice for a beginner. bringing a spur into contact with a stop screwed into the noseblock.AEROMODELLING THE BASICS OF. how but with a greater under- movements can be used to prolong flight (q. This was a carryover from full-size gliding. which could upset the model's gliding way is trim. to start flying Some models are easier than others in this one time a glider be a machine that respect. worse. a rubber-powered model provides the best possible groundwork for future flying success. trim. to the number of strands specified and the ends secured with rubber bands. while a sailplane was capable of soaring higher after release. Winding a rubber model with wifely help! Long grass part of Old Warden aerodrome. tied off and the ends bound under tension with knitting wool to make one large loop. However. Model gliders can be anything from paper-only to tiny balsa chuck gliders of perhaps 6-8in. method This the propeller fully unwound stops rotating before the rubber is in the same position every can be placed so that the blade or blades of a folding prop always assume the same position. Another to spring-load the propshaft so that one for their first attempt. essential for a and since it stops time. when the stopped a freewheeling mechanism automatically disengages and allows the shaft is propeller to windmill freely. Rubber strip is measured out. so that when the two ends are brought together the rubber intertwines to make a skein of the required The idea is to have the rubber hong between the hooks without uneven knotting length. the stop consistent Alternatively. has been available for more than fifty years! It . or sagging to the fuselage floor. least for thie before the last doubling.v. is it moves forward as the tension comes off the unwinding rubber. Success is far more likely if a very simple functional model of at least 24in.5 times the distance from the propeller shaft hook to the rear anchorage point and the motor is braided by putting on turns choosing a scale model and.) the terms have become effectively interchangeable. a glider (or sailplane) needs to be towed up and the skill required to tow has to be learned. Building and flying (600m) span is chosen. a small to build and really much more fun to fly. span (150-200mm) and flown indoors. at was considered to descended from its point of release. Gliders are undoubtedly way the cheapest and perhaps the easiest to trim for good flights. Contests usually count the best of three of nine flights. is models launched with a catapult sisting of three-quarters of line. True catapult launching.ABOUT MODELS (3. can be dangerous for onlookers or passers-by since the model's initial speed con quite easily exceed 100 mph.) and flights of over half an hour have been timed.one strand it is just a length of Two contrasting examples of gliders. most common and can be virtually any shape or size. Power models. That on the left is an A2 contest design of moderate complexity.officially hand launch or HL gliders . or made off to a peg fixed securely in the ground. Chuck gliders . for large gliders Bungee launching possible using surgical smaller while tubing. notably anti-warp wing structure. steady climb band. to the height obtainable with the length over the hook it pulls the thread forward. using very strong or multiple strand rubber for a hand catapult. braided Terylene fishing line of about 251b (11. which is held to not have to be super strong . its can be usually con- length normal is it quite possible to lose them out of sight (o. It has to be strong which tends to make it heavy.o. flights of 30-40 seconds On or more. There is a smaller Al by no means as popular.s. and it is likely to have a pointed nose making a fairly lethal projectile. The class of glider is the A2 (sometimes called Nordic) which is 6ft.5m) and capable of very long 137in. The rubber does thread tied between the towhook and a little horn on the rudder. many experts use nylon thermally day monofilament but this has a tendency to tangle on the winch drum and is not recom- and sensitive to any slight lift. pulling the rudder central against a stop. for bigger models. (5 x 1mm) usually being one side to produce a turn by a When thin in the rubber adequate to provide a gentle. Towline gliders are normally very efficient dethermoliser. full of line.5k) breaking strain. a standard towline length of 164ft. or so (around 2m) span. so that under good conditions a means of limiting the mended flight (a off thie flights for beginners. explained later) is desirable to avoid a flyaway. which is a simple device which helps to ensure a straight tow but allows the model to circle when it comes off towline and one-quarter length rubber strip the towline. Mostly as used for rubber models. class Open which is class gliders are often 50in. This term embraces a . They also use an auto-rudder. while on the right is an example of real simplicity. although in some competitive events they are divided into below and above a certain wingspan. (50m).require to be thrown upwards at about 60 degrees and should moke When the ring of the towline the rings pulls the slips off rudder main competition to its is slipped the rubber band turn position. The line may be Terylene thread or. of Vuin X Vsoin. Care is needed. 5m). combustion can be taken an internal may be spark but basically mean any model to engine. canard. They can be quite small. parasol) followed by 'contest' or 'open cockpit' etc.5m).S. 2.OlOcu. An adjustable . with possibly the addition of some nitro-methane.5cc bustion stroke ensures that the plug glows generalisations. Engine are expressed in either cubic centimetres (cc) or cubic inches (cu. Other less common labels may be used for unorthodox designs . mid. in.effectively a cylinder head which can be moved up or down . Model sizes (for free flight) do not often exceed 8ft.. diesel. Charging is is all that often from a dry batteries or a car accumulator. The glow are around O. In the latter. offer a quiet. span (2. wing position fit either may be used (high. although some enthusiasts have two or set of cells ready charged.61 cu. pusher. Most types and sizes of models can use electric power. (500mm) span. are used as shorthand for the two main types of model. lOcc sizes glowplug. . this pylon U. so that all charging can be carried out at home. in F/F. ignition results from compres- sion of the fuel/air mixture in the cylinder. There are different and additives for various specialised purposes. the most popular range being 3-5ft. ornithopter etc. (0. or any larger size you choose.controls contra-piston the compression.16cc) but the smallest in popular use tend to be 0. some of which can climb out of sight overhead in under half a minute. are more often seen in the hands of sport fliers. running on carbon dioxide charges from cylinders made for putting fizz into soft drinks. sufficiently to ignite the next may be oils and the battery disconnected. Strange model of wing well above the fuselage on what might be described as a forward fin.delta. while they can have high very wide field. (•045.THE BASICS OF.75-1 cc anol) is initially created by a low voltage battery being equivalent to 0.) and in competitions although these are brood in. in. low. shoulder. more running on ether/castor oil/paraffin or similar fuel. (0. as indeed there are with diesels.). origin has terrific performance. this 1 5cu. each capable of giving several flights. clean and three sets of easy-starting source of power for small .-061 cu. the largest size likely and castor oil. perhaps 20in. AEROMODELLING to unaccustomed eyes. performance. Two words. CO2 motors. it bears little resemblance to any full-size carries the aircraft but the configuration has controlling the proved means considerable power used the most efficient and reliable of in very high performance competition models. pylon and cabin.) models are the major development 1 980s and 1 990s. where the engine has a permanently glowing plug in the cylinder head and the fuel used is methyl alcohol (meth- with rare exceptions. but if a design does not clearly general category. A pylon model 10 being The smallest commercially available but once running the heat of each com- ( in. the resultant temperature rise being sufficient to cause combustion. and if fast recharge cells are used two or three Electric story of the minutes charge between flights may be needed. Cabin models bear some token similarity to fullsize aircraft and. or compression strictly ignition.9— 1. . it fitted with This ignition (often called petrol or gas motors) but relatively few are seen. in. made possible by progress both in nickel-cadmium cells and permanent magnet motors. has been said about scale models because although they are popular for radio. to model which 3 cc glow engine with a pusher propeller between the fins. which Little is not necessary to give a helpful when full trimming. not all scale models are easy However. this Mom'selle is using electric power which gives clean and quiet flight.ABOUT MODELS Originally designed for free flight with a diesel of about 75 cc. and it is charge. really so a little to be lightly experience with other It is possible to adjust a motor's running time per charge to a long run at low power or a short run at high power and pro-rata. uses a tiny 11 . The motor is almost invisible in flight. repairs are likely to be more prob- mended. but there are one or two smallish free-flight designs based on military or semi-military machines. tow up. Since they are also more complex and take longer to build. Flights attempt a scale model experienced. models up larger if about 30in. or to built lightly to fly indoors. (750mm) span. lematical. scale models are The models the need and are likely to is until due reasonably to the fact that more difficult to trim and sustain more damage if they hit types of models should perhaps be recom- ground in the early stages. There are relatively simple scale neatly built. This are rarely of extended duration but can be enjoyable in small fields in calm weather. this book is concerned with basics and a newcomer to model flying should not A Concorde free flight models many (of simple full-size aircraft) but so beginners seem to want to tackle a Lancaster or a Most scale Spitfire! gliders are large radio- controlled slope soarers. Scale rubber models are often quite small. some- trainers for once the novice has learned a reasonable amount about building and trimming for flight. They can often be less difficult than a rubber model since they have a constant source of power as while one of the experts opposed scale-like thing to tackle to the considerable initial burst of energy from a rubber motor. AEROMODELLINC A free-flight model Fieseler an example of thie hiighwlng layout most successful for Storche. Most R/C clubs have one or two members prepared and may actually have new members to learn to give tuition Scale power models are.. to allow the trimming procedure to be carried out more cautiously. moreover the engine can usually be throttled down. or kits 1 should be avoided by beginners as they usually employ very small components and skill and experi- material sizes which need ence to assemble satisfactorily. Small scale models.THE BASICS OF. trimming it a will many on. Never- 12 a new model for clubmate. most experts are apprehensive initial flight trials with F/F With radio. a power scale model of almost any subject can be flown in the hands of an expert flier. Most of the models are scaledup vintage magazine or kit designs. F/F models. theless.. take on flying experienced less out so that as possible for the builder to club fly. Learn to fly a trainer model on the same number of functions before risking a scale model. it is as safe There are and sport type designs of appearance (but with the emphasis trainers on docile flying characteristics) which offer a far better chance of success than being overly ambitious at the outset. It's often expressed as learning to walk before trying to run! . 40in. but a jumbo rubber class (minimum span when conducting m) began to attract a lot of interest around 1 990. or at least run on a very rich fuel mixture which slows it. again. such OS a wing rib or fuselage former. it is claimed that experts tend to weigh each piece but older builders rely on experience. A tree grows to success only maturity in greatly affected or seven years and six by variation. while that cut on a tangent will bend relatively easily. models or for soft block shapes such as engine cowls. characterised by large. and 10-1 21b for hard strip. the on a dry hillside or in a damp hollow) and similar factors which have less obvious effects in slower-growing timber. There are two main cuts of balsa depending on how they relate to the growth rings of the tree.g. 8-1 Olb for stripwood (the smaller the harder) and for 'hard' sheet. Thus a tree may be full of faults and inconsistencies of hardness. the term 'model aircraft' immediately brought to mind balsa. The grain pattern of balsa is seldom very obvious but radial sheets tend have narrow-spaced parallel lines of short grey or golden brown dashes and tangential sheets possibly a few broad to 13 . In general it is preferable to use occurs. or incorporate vacuum-formed polystyrene parts and possibly high-tech materials such OS carbon fibre. Fortunately. For model use the weight per cubic foot may be quoted . (e. strips cut rather than to try to bend one thick strip to shape. Balsa varies considerably in weight from spongy material to the density of oak. Clearly. but nowadays many models employ glass-fibre fuselages and veneered foam plastic wings. feel and 'bendability' to an adequate extent. often indoor. rolled tubes etc. most of the sophistication relates to radio-controlled models and the basic home-built flying model is still a balsa frame covered with tissue or possibly nylon. weight and even colour. strip two or three thin round a former laminated together from thick card etc. is very light best cut from a radial sheet while tangent- top grade balsa at reasonable prices. 6-8lb for average sheet sizes. but a wide choice of is and self-adhesive. many uses have been found for poorer quality wood which means that it is possible to buy wood walled is channels and cut. although film coverings are becoming increasingly used. the budding builder soon learns to differentiate between grades by appearance. boron etc. which makes selecting and cutting grades suitable for position in which modelling quite it is difficult. cut stock should be used for curved members such as wing upper surface sheeting. a component requiring stiffness. A sheet cut on a radius will be stiff and will split along the grain. The flexibility damped. Balsa is a fast-growing tropical timber mainly found in South America. However. thinwith interspersed cells is full of sop when though once dried out it is feeder the tree is difficult to reintroduce moisture. In fact. Covering used to be confined to now there some fine silk or tissue. capable of a all degree of shrinkage by the application of heat. For extreme flexibility soaking in ammonia will allow remarkable manipulation but again this must dry out before cement or glue is applied. plastic films. other than by pro- longed submersion. notably Ecuador. kevlar.4-6lb for very light. but recently cultivated with some in New Guinea.CHAPTER TWO and materials Tools For many years. except to a shallow depth on the surface. When well A is greatly increased but swelling soaked for bending must be pinned to shape and allowed to dry out before cementing since the wet and dry lengths can show marked variation. chemical deposits grown in is weather seasonal the soil. Reversing strip positions allows the best match to be made. slightly different shade from the basic colour. the symmetry of a fuselage. No attempt should be made to force a cut in one stroke. Millimetres inside it. 2. obeche can be used although as thin ply is easily available this material now encountered less frequently. Use a fretsaw for stringiness for curves and a razor saw for straight cuts one strip degree than another of the want of o better word. always allow for the influence of grain and make the cuts in make the grain steer blade away from the component being a direction which the fibrous length. Frequently one end of a strip bends more readily than the other. Spruce is stronger and 'whippier' than balsa (it is Ve 3 also heavier). is exists at the will cut rather than into it.0 normobeche and beech. Fig. this will easily Its weight indicate is with a shop's stock! or impression in balsa Dampening a dent will usually swell the and remove the impression. % % V2 % 1 5 6 9 12 18 25.8 Vu 1. strips should be cut sequentially from a sheet (after marking one end) but this sounds easier than it is in practice. or in Of visible pattern at all. Beech the usual material for engine bearers 14 is is and . Balsa up to around y4in.4 ally spruce.THE BASICS OF. For the most exact matching. If sheet material stronger than balsa is needed. less crushed a reduced danger of slipping. noting the curve each strip adopts. TABLE Approximate Imperial/Metric Equivalents in Balsa Sizes Incht an essential either as a sheet wrapped around a block or glued to a strip of wood. soft may have one or two surface fibres cracked — but don't make a habit of the sheet stiffness. Glasspaper. result with cutting from sheet.medium hard will take an impression. but is sometimes used for fuselage longerons or wing spars on larger models. or an impression can be made with a thumbnail . so may bend to a much greater that similar weight before snapping. or to hold strips by their ends flat on a table edge with all but an inch or so overhanging and compare the droop.1 TongenI cut widely spaced.scrap it and try again. (6mm) thick can be cut with a sharp bladed knife or scalpel unless it is very hard. It is better to cut just outside a line and then sand back to the line rather than risk cutting exactly on the line and then wandering is 1. only lines. Hardwoods used for models are '/32 0. many intermediate really no course. hard will barely be marked.5 2. Never struggle to make a cut when the right tool would do it easily and never accept a is faultily cut piece . there are cuts between falling these two extremes but gentle pressure with a thumb against the fingers at the end of its degree of an indication of how hard it is likely to be. or other abrasive material. wood if hard or thicker than y4in. Two simple checks are to pick up two strips by a forefinger at each end and press lightly. several fibre balsa light cuts will When or achieve a better. AEROMODELLING . Long always preferable if a choice approximate weight required since it results in a stronger and more crashproof model. fibres Balsa also varies in which can obviously affect say. may be seen in dowel form and bamboo.the number of plies is not an indicator of thickness and multi-plies are heavier (due to increased for modelling.5mm). but it is desirable to place a scrap piece of ply underneath the piece to be cut and cut through both otherwise the flex of the ply will snap the blades and may distort the cut. at one time common in models. it has considerable strength but other timber sometimes seen to a very former One jelutong. glue content) advantage any without offering Vi6in. Fine-toothed saws are best for cutting Plywood hardwood. Up to the 1960s such wire would snap if an attempt was made to bend too tight an angle. once sold for modelling. or thinner in ply can be cut with stout scissors. Ply is much heavier than balsa and used only at points of means edge and use trimming to the may carry engine bearers. Birch strip. ranging to Vein. and small 15 . rubber models and small power and that the higher the number the thinner the wire. However. All these sizes are three-ply . This shafts straight has led to competition fliers increasing the wire thickness over that previously used. For anything attached and which is straight lines all with the aid of a steel straight the fuselage to which the under- in carriage lems. a size only used on larger jobs.a wing spar reinforcestress or also as a basic material steel steel or plain steel necessary for both straights and curves. is is heavy.4mm) (3mm). (0. Sometimes 3mm luan or gaboon ply can be used in place of birch as it is lighter but retains stiffness. of oil sizes in the thinner sizes useful from '/64in. may take a set so that after a heavy may be necessary to straighten the wire landing it the assembly to its It goes heavy and the original position. Wire thicker than final '/i6in. a saw is in modelling piano wire. tempered and plated. The best scissors for the curves. A fretsaw can be used. When used for undercarriages the springi- ness usually is adequate but if overstressed.. brass or etc. There is also fuses. Size measurement is quoted in Standard Wire Gauge (swg) which should not be confused with any other gauge. Larger models may call for thicker ply.or a forward quite and must be split from garden canes. Typical examples are a dihedral keeper . The accompanying table should prove helpful.8mm) and '/i6in. for very light models) shape with a knife and glasspaper. very thin aluminium sheet (e. the best of which is hardened. Anything outside the line - good the remainder will trim off with a strong sharp knife-blade. some soft drink cans) for bendable hinge tabs possibly where great strength is required. but always cut a '/i6in real for modelling purposes. this is the reddish coloured material often used on interior flush doors. (1. Note that 1 6swg is Vi6in. light smooth-grained used for carving rubber wood sometimes model propellers. but the two most-used thicknesses are '/32in. Very little other metal is used in the average model except possibly small scraps of brass sheet or tinplate which may be used for bearings or freewheel devices.g. This creates when used is prob- for propeller on rubber models which have to run and true but which will bend if the model goes over on its nose on landing. Single strand control-line wires are likely to be is 33-38swg (the latter and can be stainless but not piano wire which too springy and would prove difficult to handle. these do not seem to have the hardness and strength of the Tonkin type AND heat shields for and dethermaliser aluminium tube for bushes washers (usually tinplate hemispherical cup washers but also occasionally flat brass washers). now is only occasionally specified previously sold. This is much easier than cutting the whole piece with o knife technique is to in the first knife-cut place.TOOLS dowelling. but nowadays all that can be obtained in the USA or UK is much softer. particularly usually comprises birch sheets laminated together MATERIALS ment at the point where the spar is cut form a dihedral angle . without saying that steel is minimum of wire should be used. (0. may also come printing You across litho plate which very thin aluminium alloy sheet used processes which. AEROMODELLING . the highly stressed areas since they are very make heavy.0394in) is recommended least 1 V2 .THE BASICS OF. Always read the manufacturer's instructions with any adhesive as there are many . However. for larger models.5 The second group the possibility of an into a tiny eye e.75 V27 15 1 V20 21 1. V53 0.25 V16 3.104 %4 %4 0. Drying times vary from make to make but models. Plastics have only built it that non-stressed joints should be is 0. usually expressed in inch decimals. but with the advent of balsa. but and hardener.and left for at hours before handling . However.5 V32 12 0. we are discussing basics rather than advanced techniques.g. Slight abrading of the surfaces with a file or glasspaper etc. Setting time can be as little as five minutes but full strength develops over some hours. The cement Inch Closest Millimetres fractions US Music (to Gauge '/4 7 0. metal to wood) or from acetate sheet for cabin windows. in is some when salvaged and cleaned up. ensures better adhesion.128 0. WIRE/SHEET METAL GAUGES first British modellers refer to "piano wire" measured by Standard Wire Gouge. Modern covering products made from plastic films.carefully that joints where any strain exists are allowed a minimum of 12 hours.g. These glues are easy to apply and wash off fingers etc. canopies and. In the very early days animal glues were used. are frequently these bought. odd to made pin (perhaps guide an auto-rudder line or simply acting as an anchor point for o rubber band) and.25 ing to dry for 20 minutes or so. with a power model. nuts and bolts to secure the engine. including metric SWG 26 22 20 Inches 16 14 12 10 8 . introduced to modelling in the late 1970s. dummy engines and cowlings. cellulose cements were introduced and became known as balsa cement. is widely used for cowlings etc. treacly paste which will bond almost any two grease-free surfaces materials may be builder of a basic use of plastic. as in carpentry. aliphatic resins relatively etc. Adhesives are available in a quite bewildering variety but there are four main groups used in aeromodelling. easily with water before completely dry (as opposed to balsa cement which dries on fingers and has to be picked but they need close-fitting joints and a degree of pressure while they dry.036 0. on scale power models.018 0. The best joints are obtained when the joint faces are freshly cut and/or sanded so that there is no likelihood of any greasy dirt on 4 the surfaces. apart Epoxy and similar two-part resins form group and in aircraft should be reserved only for very strong joints between dissimilar materials (e. as model is in plastic may cockpit unlikely to and other materials used are dealt with of in covering a later chapter.048 0. which have to be mixed very thoroughly immediately before use to form a thick.080 0. This is the 16 the third resin with the exception of some plastics.5 2 2. Nonstressed joints can usually be handled with care after 1 5-20 minutes but others need a minimum of 2 hours and are better left off!) overnight. although there is on official Music Wire Gauge. the classic 'leave to dry overnight'. then recementing and bringing the faces together.028 0. They usually consist of two parts.160 '/64 26 30 35 39 "764 - Closest formulated to soak into a balsa surface joints can be achieved by lightly cementing both joint faces and allow- and stronger mm 1. . Americans by the term "music wire".064 18 (1mm = of the four groups. This table provides approximate equivalents. Very little pressure should be applied. and various types moulded from home- limited use in Wheels propellers consists of polymerised (PVA or and are new on the scene having been resins such as polyvinyl alcohol white glue). cement or PVA will cope with everything needed for simple and pastes initially (see later) at least. react to common you do get your fingers stuck Some builders assemble complete models using no other adhesive. useful for laminating blades. virtually instant type is the most The common in modelling. then spraying with However. glosspoper. a modelling knife. modellers use single-edge (backed) safety razor not OS sharp as was once standard. Of as are surgical scalpels with inter- changeable blades. followed by glues which do not cure a second component is sprayed baking soda as a catalyst for immediate curing and most can be dissolved by glow fuel (methanol). irreversible be used in damage so they should always conditions of proper ventilation. offcuts of MDF may be available from a building firm be careful. As will be seen in Chapter 3. of all the glues mentioned. curing times etc. paints and other items related to covering finishing discussed in Chapter 5. some resins are almost watery. course.g. dry. Always use a slicing movement. often termed superglues. and with cut with down of strokes rather than try to force a heavy pressure. although those available today are sheet materials. The fourth group are the cyano-acrylates. a board 36 x Sin. Similarly. creep into every joint. cut the grain rather than against it and on a wood board. Alternatively find a metal merchant who may have inexpensive strip offcuts of approximately '/i6 x iy2in. the MDF takes pins readily. . a pastry board or similar) can be found. that the groin of the cutting surface does not cause the blade to wander off-line on thin sheet. but actually conwidely different products with of sisting differing viscosities. nor do card or moulded polystyrene parts. For models of up to approximately 50in. they can be resharpened on a fine stone.5 X 40mm). dust- and grease-free surfaces. (900 x 200nim) will prove adequate and with reasonable care will lost for years. until Many on. only be as true as its board and the best procedure is to glue a piece of 10mm MDF (medium density building fibreboard) to a completely piece of flat blockboord or chipboard. others almost too mixing is stiff to mix. which if inhaled can cause the setting agent. cyonos give off the most dangerous fumes.TOOLS variants. TOOLS One replaceable blades are much more major advantage of building simple models is that very few tools are needed. Croft knives rubber solution for covering sheeted surfaces with aluminium foil and various clear general-purpose glues such as tissue cements common plastic etc. latex for veneering plastic foam shapes. pastimes or ruler are available building sports it is still Any model relatively will little. polystyrene cement for For cutting. . compared with most hobbies. With sheet. applying drops of cyano to so if . but this is not essential. For more complex models rather more is needed but. Always use a metal straight edge when cutting straight lines . they hold their edges as well.g. a few pins and a tube of cement are all that is needed to moke a chuck glider which will give hours of fun. However. (1. if cutting 17 . Apart from the lamination of two boards which helps to resist subsequent warping. but thorough) essential as ore clean. contact odhesives. These are sharp and should be treated with care. and it is AND MATERIALS taken for granted that a pencil and that a small board (e.this can be a piece of ply or a redundant breadboard or similar.even the bock of a hacksaw will suffice. For deluxe builders it can be topped with a selfhealing cutting mat available from artists' suppliers. placing everything in position. some of which have particular applications still e. A separate small board should be used for cutting .250mm) span. many experienced Of course there are other odhesives. (1. balsa Other materials used are mostly dopes. even when cutting through small square strip. and make a number models. A small essential drills. if necessary. ana that of reasonable size can stalls in markets. it is not possible for normal wire cutters. Hardened steel dressmakers' pins are usually used for the temporary pinning of structures. should be acquired as the toolkit expands. hacksaw. Similarly. thick it can be used for accurately notching components.THE BASICS OF. For anything 18swg. They can be withdrawn by twisting with pliers. gripping the shank with pliers or. 18 fair size iron. tapping gently in with a light hammer. pushed in either by hand or by using a coin on the head. as used in manicures. plus perhaps a heavy duty DIY knife. However. gas-heated bit Ideally a junior be used — often available cheaply from secondhand and razor saw surplus tool cut down from something harder or thicker. is needed when a part has to be watts or thereabouts. beware of too much stress on the heads of the latter as the glass can shatter under pressure. especially if they are in contact with cement. immediately apply flux spirits of salts') A basic tool scalpel. not an angle or the wire will and either snap or remain very to too sharp crystallise weak. If the flat file is Vi6in. A with plain copper. to cut piano wire without themselves being the corner of an old when it will file damaged. or more properly garnet paper and/or carborundum paper in fine to very fine grades. On very rare occasions a carpenter's tenon saw might prove useful. A 'tool' which is essential and which should be used more than any other is glasspaper. ended spanners. are helpful but a sheet of glasspaper pinned or glued 1 x 2in. Trying to bend piano wire with too light a pair rapidly ruins the pliers.. snap in the pliers. triangular and warding or flat . batten will be found an asset throughout construction. a fretsaw and a a miniature tenon saw) should be in the toolkit. T-headed modelling pins may be used if preferred or alternatively glass-headed (like pins. At least two pairs of pliers are needed a heavy-duty pair which can be squareended and a lighter taper-nose pair. is (Baker's Fluid or 'killed and use a a sharp modelling Remember not 50 knife or surgical to use excessive force blunt blades lead to accidents. should take care of just about everything. AEROMODELLING if a timber yard does not supply cut pieces. or pliers with wire-cutting features. These.. a steel pin can be gripped between two coins for removal. Desirable but not perhaps immediately drill plus a few small is a hand The hand drill can also be used to wind rubber models! Small files . use a small vice for thicker than bending bend obtain better to Do results. To solder such wire. Nothing shrieks 'beginner' more than a finished model which quite obviously wasn't carefully sanded to remove odd bumps and lumps and unintentional corners! to a foot length of . electrical screwdriver and a slightly larger general purpose type are useful kept in good if they are and small openbox spanners to fit condition. If you do not have any pliers to hand. or 60 A saw tinman's solder.round or rat-tail. plus two or three small sizes of nuts.have many uses. clean it thoroughly with abrasive paper. Emery boards. but most households have a few basic tools. Use to nick the wire. tools. which example is of a tool which some people - usually builders of bigger models - find invaluable and others never use at all. Remember too that a poor model can easily be made with good tools but it is much harder to make a good model with poor tools! 19 . The same can be said for spray-guns.TOOLS addition.you will soon find that your collection will build up. you could invest in a razor a small smoothing plane using double-edged razor blades. Buy only such tools as you need for the current project . balsa strippers and a power host of other items AND MATERIALS which are not required unless an obvious need arises. This is an In plane. simply then fold 20 it make a copy and along the fuselage bottom line. Take the paper gliders illustrated: a whole fleet can be made from two or three pages from an exercise book or a couple of A4 sheets of copy paper plus a cocktail stick or one or two matchsticks. (12mm) of cocktail stick (or a slightly less length from a matchstick) and secure it in fold the wings lines). of course. Yet another way is to hold the page against a window pane with the copy paper held on it . You could.CHAPTER THREE Paper and chuck gliders It is surprising how much can be learned from the simplest of models at almost no cost. point it down vertically and just drop it. it may be is halfway to the floor. Alternatively. Having traced the shape. then hold the copy face down on the paper and rub a above your head. using only a trace of almost any adhesive or even a tiny scrap of adhesive tape. place the domestic iron over the back. which will transfer the first lines. the flat fuselage and a small amount of V in the tail halves giving directional stability. It should curve into a glide warm before the drawing on a 'dry' copier. then turning the tracing over. You can trace it by pencilling over the lines on to a piece of kitchen greaseproof paper. cut out the folded paper with scissors and accurately and tail (follow the dotted Note that on this model there is no fin and rudder.you must Or photocopy the folded paper position the fold accurately. . place a piece of carbon paper between the page and . laying it accurately on the folded paper and going over the lines from the back with a pencil. The glide steep. the nose fold. The softer the pencil the better the lines will transfer.if the light is bright enough you will be able to see the lines through. indicating that there much weight in the nose. or it may be is too stally. Now cut about y2in. Trace the one drawn using a fold in the paper at the bottom of the fuselage. Now check that the wings form a slight V (the dihedral angle) and have not become model twisted with handling. PAPER The completed model from the drawing opposite easily fly 20-25 ft. a separate rudder aircraft can be cut and fitted in the fold at the tail end. it will give you some idea of its speed. With any hand-launched model you must try to keep the fuselage at a constant angle and pointing slightly the arm forward flying nearly downward while swinging to release the model speed. This will effectively give the model ailerons (on the wings) and to elevators (on the tailplone). raising the leading which will give that wing a bit more edge. which means that more weight is needed in the nose. or the leading (front) edges of the wings upward. but you won't be flying these at first!) The commonest faults ore to try to throw the model and/or let its nose come up as the arm moves forward. lift than the other side and will therefore turn the model. while and you are experimenting you will subconsciously be recording data which all of you can draw on for later. All fly well. possible including in which can be made to fly well. in the latter case the weight will be more than is needed and the model will fly faster than if the weight had been left where it was but with a little trimmed off it. swooping up then dropping sharply before picking up speed end swooping up ogoin. a and a biplane. (say AND CHUCK GLIDERS will 7 m) Indoors. You can. To adjust the glide of your paper model try either reducing the weight or adding a little more. deltas. You can also cut a second identical model but glue the weight slightly farther forward (if the first one stalled) or farther back. aiming at a point on the floor 10ft (3m) or so away. Although the paper will not weigh much there is a danger that the adhesive might. including a dragon. canards and of the original shape. Either way. If the model flies straight and you want it to turn. more complex models. put a In order to achieve a more conventional appearance. trapping the fold the fold Many variations are seagulls. A biplane may be made by cutting a long thin wing and folding it. if you wish. point the nose slightly down and gently push it forward at obout its flying speed. Try competing with friends launch while standing on a step-ladder and see whose model travels the farthest! one wing. Examples of paper models. (The exceptions to all highly powered this at its are competition models. put a small fore and aft cut on the trailing edges little twist in of the wings and tail so that you have a tab bend up or down. so be sparing with it and remember to compensate at the nose end. so for further flights you can hold it under the wing. seagull 21 . Alternatively you can cure a dive by bending the trailing (back) edges of the tail halves equally upward. THE BASICS OF. 22 . . AEROMODELLING . often lift On a good over a minute are length of time.put a piece of flat wood on top and then a book on top of that. using strokes along the grain but angling towards the edge. Cut the wings and tail pieces and sand them with fine glasspaper. Cement them together and leave them to dry on a flat they will a small increase very slight membering in lift efficiency. and run a thin line of cement along each and put aside to dry. When the fuselage is dry. This is it its official the other exception to launching at flying speed . This may not sound very long but just sit and watch the second hand of a clock or watch and think of a model in the downward is air for that 'thermally' not flights of uncommon and a surprising these simple aircraft sight. This is can be used to retain the same stability as a straight wing would give while allowing a slight reduction in dihedral angle and hence wing. These two pieces should be cut sweepback. tail circular so from the hardest part of the sheet if there is any obvious variation. usually at a 60 degree angle and banked over at 60 degrees.a chuck glider thrown upward as hard as possible. An average flight for a beginner will probably be between 10 and 20 seconds. so having marked and cut one. 23 . it con be used as a template to cut the second. Both the wings and toil will benefit from having the leading edges rounded and the trailing edges thinned slightly. day do in fact number fly upwards. or hand-launched glider to give title. (1. so that they are cemented have what is called an aid to stability which very simple example of a chuck glider.5mm) moderately soft balsa if you prefer rather than trace them. sand around the outline to ensure that both parts are flush. Sand a bevel on each centre end. This is made up of two identical pieces cemented together.PAPER The next simplest model is a chuck glider. when there is of out of good GLIDERS surface under light pressure . Do this by holding each piece on a flat sheet of timber with the trailing edge flush with the timber's edge then sand gently with the paper on a block of wood. It will teach construction and trimming lessons as well as being fun to fly. The drawings are shown AND CHUCK full-size for a when angled. The finished chuck glider from the drawings opposite. The together and rudder tips are all semiyou con draw the pieces on a sheet of '/i6in. Sanding balsa creates a lot of dust so it would be wise to either sand out of doors or in the garage rather than indoors. though you will need to trace the fuselage. then mark the wing and tail positions. rethat one wing is left and the other right. You will notice that the centre ends of the wing halves are slightly about. As has already been mentioned with the paper model the glide may be steep . 3. You can. oil leave to dry then sand all over with very carborundum paper. these are all coat of cellulose 'varnish' to strengthen and waterproof the balsa surface. stall. Sight from each end to check that the wings are properly aligned that the tailplane and fin Check the model the using a pointed knife-blade or and are truly square wish. When dry. and again pin temporarily to the fuselage. using books or tins to pack under the tips to hold them at an equal height from the board. (76mm) and using two pins at the joint end to ensure contact while the cement dries. or thin polythene (from a food bag under the straight end. recover flying speed then climb may be enough to achieve a nice smooth glide straight away. set the fuselage vertical on board and press a pin into the board each side to hold it vertical. without pinning the through it. a couple of temporary pins can be pushed in to make sure it doesn't move. Cement the wing in place. hold the model with a finger and thumb beneath the wing trailing edge. blocking the tip up Sin. packing loosely under each tip to ensure that it is parallel to the board.THE BASICS OF. point the nose slightly downward and launch smoothly and gently. For the 24 I it is first tests. because obviously grass model which is will fails cushion the arrival of a to fly properly at first. Cement the tailplane in place. the corner of a razor blade holding with a clothes peg off tail all Round and the corners except at the wing seats. throwing a dart but is not as hard. This true alignment to dry out thoroughly then fine akin to a as Leave you it and in alignment. ensuring that is etc.but keep your fingers out of the way! Now cut the two extra nose pieces and cement in place. When you have achieved what lucky 90° Right if flown over grass rather than tarmac or Fig.) exactly at right-angles. banana all over. Place board and moving too film dry. very impor- add thin fillet of cement along the joints between the wing and fuselage. and the tail and fuselage and again leave to dry.1 I This not so important with a chuck glider again and repeat the sequence. the aim being to release the model at to normal flying speed. for a stally flight add a pin and try again. or clear non-shrinking dope. Cement the end of the other wing and fit in place. AEROMODELLINC .even much drop to as a dive — or it may climb. Traditionally. looking at a spot approximately 25-30ft action is rather like in The front. until the nose-down when slightly supported by a fingertip in the centre of each wingtip. until (or one wing panel on a weight lightly eosily waxed and slide to it a flat prevent it strip of kitchen paper). Be a patient! although it will certainly last longer gravel. or drill and push in bits model balances a couple of holes along it of cored solder. Now the nose. Also sight from above to make sure that the wing and tail are squarely tant. V where Carefully excavate a shallow wing will sit . To correct too steep a glide it will be necessary to remove a pin or piece of solder. Naturally this has be a guess at first but will become easier its with practice. give Wrong . You is push several panel pins into the thickened part of placed. if a coat of sanding sealer. Also at this time cement the fin to the tailplane. all models ore supposed to be test-glided over long grass. However. pointing it slightly upwards and slightly banked. i.e. Clearly. boom and a appears to be a reasonable glide path. you can launch the nnodel harder. it will probably stall and may well drop straight to the ground without resuming gliding flight. that its pitch stability is marginal and it must be flown in such a way to prevent it getting into a critical position. if the aircraft's speed is increased dramatically. Watch what happens and check whether the same thing occurs on every flight. with the tailplane at zero angle this arrangement helps stability in pitch. It follows therefore.v. It means that if the aircraft is disturbed from its normal flight path. a force arises which will tend to restore normal flight. The reason for this is that both the wing and tail are mounted flat on the fuselage. without at how enabling stalling. a chuck glider thrown much faster then its normal speed cannot have an incidence difference or it would simply loop every time it was launched hard. If the model is launched at moderate speed upwards without banking it.).PAPER A AND CHUCK GLIDERS high-tech chuck glider equipped with a carbon-fibre dethermaliser (q. Banking the model on a launch turns any looping tendency into a which is flying spiral climb. the difference in angles produces a tendency to loop.. A normal aircraft has the wing set at a slight angle. far the it to slide into a glide You may well be surprised model will fly from a good hard launch once you have got its trim right. neither has an angle of incidence. adding or removing a pin as appropriate. perhaps 2-3 degrees on the average model. 25 . of course. there are borderline cases as with a bulkhead fitted to carry the undercarriage in a rubber model which has to have centre cut away its rubber motor. Sometimes curved addition is confined only to the nose of the fuselage. sometimes referred to as 'stick and tissue' modelling. usually in the form of a slobsider box carry- proof paper to prevent excess adhesive sticking the structure to the drawing. for appearance or Strong curves this ing or soaking the strips. notably light weight. The basic box fuselage fore and aft strips called is four longerons. ending up with eight longerons instead of four! This sort of fuselage have bulkheads or formers. A present-day complication is the switch from to imperial measurement to metric. the longerons are placed over the drawing and held in place with pins pushed in either side of the strip. patience and commonsense list but a few of its characteristics. traditional construction means tissue-covered balsa framework. modest tool requirements etc. Slip the tube and boil the kettle two or three minutes. For free-flight models the method has much to commend it. easy repairability. quite a to streamliners wood square or rectangular stantially which the sides are erected. held place by vertical spacers to 26 built with make two in sides Alternatively rub the and in allowing in site longerons them to the spacers. shaped turtle deck on top and/or bottom. as the plans available are expressed and young potential modellers in more inches familiar may find difficult dealing fractions. Pins pushed through will majority of fuselages for models are what joined by cross-spacers top and bottom. The tube will have be supported in some way and it gets . Some balsa is now cut in with millimetres with inch most of it metric sizes but most (at the time of writing) due Further problems inches. of every joint may dry A entail on steam- them down out before piece of light metal tube taped to the spout of an old kettle makes a wood strips into the for to suitable steam box. and stringers to the basic box. the finished structure. To build a slobsider fuselage. cover the plan with kitchen It is film or usual to grease- There ore. whereas a former is concerned with the external shape and therefore frequently has its centre cut away to save weight. to list A equivalent is known section as number new of builders have built two sides and then a separate top and bottom. and it has immense value in teaching dexterity. to pass the in cross- which weaken sizes at the outset. in still is arise America still works in goes entirely metric the to the fact that inches and fruitful interchange which has always existed if Britain between US and UK modellers will become more difficult. and a top view on are most often round or elliptical in section. moderate cost. structural analysis. therefore. (solid bulkhead a may sheet cross members) further carries structure such as engine bearers in a power model. as slabsiders. achieved by adding light formers the plan with a candle or a dry bar of soap.CHAPTER FOUR Traditional construction In modern parlance. meaning sub- opposed side view. This top view shows the same longerons viewed from above as those seen from the side in the which one draughtsman will call the u/c bulkhead and another the u/c former. Working drawings for building such a structure show a side view over which the sides are assembled. It seems sensible. pinning perhaps cementing ing a to gain a slight aerodynamic advantage by streamlining the part of the structure which first encounters the airflow. As ever. intermediate shapes. edge will e. resoaking if necessary. spacers. natively. 4.TRADITIONAL CONSTRUCTION warm quite strips with so it might be easier to wet the hot water. 4. the sides are vertical using a set-square. leave them to soak for Fig. returning to dry size as out. Fig. so that A it is inadvisable to severe curve should be ating strips. (above) shows one side of a typical cabin model and indicates where pins might be placed. In both cases the aim is to ensure that both are identical and unless pieces of greaseproof paper hove been laid on the sides side joints before adding the second. to move Initially. 27 . place the sides is square. and build both all sides four longerons simultaneously. curve two stick made by dries it it wet. Some modellers cut pairs of spacers before pinning the longerons.in. Once two pairs of spacers are in is con be worked between spacers as well as between longerons. using It is possible to cut a pair of temporary cord formers to help assemble the sides together.1 a few minutes then gently bend them.g. on and equal Vein. either first The rubber band can be biased the the sides with care. lamin- x Vein. place. pushing them out once the main cross-spacers are firmly until all light is rubber bonds where necessary. then pass a not-too- rubber band over them. Again. 1 A simple slabsider fuselage for o rubber model. The wood swells and lengthens. hooking it to drawing pins set two to three inches away tight either Cement in the first pair of top and bottom. Positioning the others then quite simple. others cut them to fit as they go along. attacking a stubborn unwanted joint from since useful all it round. some build one side complete then lay the other longerons on top and build the second will while others pin side. This is one occasion when. '/it. easily square when cemented together. since often over the drawing they brace the structure against the spring in place. leave to dry. two sides will lift as one and will need to be separated by working a thin blade between them. and check that side. a double-sided razor blade cement the widest pair of spacers and the tail end or the two widest pairs of spacers. with pins each side. in which case make sure that the nose and tail ends coincide by holding a square to them. Alter- In many designs there may be diagonals between vertical spacers and these should be put in as the sides are built. for example at the nose where a lot of handling may be expected. the centres having been cut out and temporarily tack-cemented back in place. Other methods include building a crutch with temporary spacers. then used as a template for cutting a piece of sheet. For exomple. the jig can be withdrawn and the former centres removed by wiggling a blade through between stringers. The thickness has decided. of a curved part. Streamline fuselages cannot be built flat same way. or a jig arrangement. (0. in this case '/(-. e. though one technique is to build two halves. a body with a straight top longeron but a strongly curved lower one will change shape when is it unpinned. the formers all have a square hole cut on the datum line. one can be built and removed and the appropriate area of the plan lightly in the damped will with thin render it oil or paraffin etc. free-flight power model by the author.g. A multl-stnngered fuselage built on a crutch is a feature of tfiis 45 in. usually left and right. Where a circular or oval but in functional fuselage to is made by it is common wound formers required. thus transferring them to the back of the plan. Formers do not have to be cut from sheet every case. or a two- 28 made as a top and bottom one view is of course adequate. and a tracing made of a then a line drawn. where the undercarriage enters the fuselage. In the latter. If the drawing does not show two halves. . This is transferred to hardboard or cheap section. A better (and less smelly!) idea is to lay carbon paper face up under the plan and go over the required lines on the right side. . and join them. For a circular fuselage. piece one to be section. top and bottom. These filler panels should also be inserted before unpinning the structure. Once a few stringers have been added the pins can be removed. which sufficiently transparent for the second half to be built on the back of the plan. putting bend a in what should be the straight top and flattening some of the curve from the bottom. (2. They are then threaded on to a square piece of timber the jig . allowing formers to be positioned on the crutch and the spacers to be removed once a few stringers have been cemented in. making an this impression of the inside corners of the longerons and spacers.THE BASICS OF.8mm) balsa. is frequently used for scale models.in. and when all the stringers are positioned and dry. A further method which emulates full-size techniques is to build a box fuselage and add formers to the sides. first say three laminations of to be '/ajin.and held with pins in their true places. and often the best method is to lay a piece of paper over the bay and run a finger round. This tends to produce a slightly heavier structure overall. In a lot of designs there may be inset sheeted bays. Strategically placed diagonals will prevent from happening and they may also brace a joint which may take a load. use what are termed laminating narrow strips of thin sheet balsa.4mm) inside the section outline. This paper can then be cut and checked. AEROMODELLING . having 29 . the edges of former between the stringers show up other) covered rather badly. stringers are notched into a former cut from sheet and subsequently tissue (or the than a One small drawback is the increased complexity of the wing mount- most often this is a parasol style using or hard balsa runners on a wire cabane. perhaps Vsin. Certainly former with the notionally aerodynamics of the latter but struction of the better without the weight. but we need ing. of greaseproof is repeated for and shrunk. and wound round the mould. most wings have been double-surfaced. cut from a suitable sheet. giving horse' appearance. one theory behind it sheet. what is called a 'starved most cases the edges can be scalloped away between the stringers or the former cut undersize by the thickness In stringers and the stringers then cemented on the outside of the former. On early models. (3 or 4. rectangular glider fuselages and on some power models. on reproductions of vintage models. such as for mounting an undercarriage or flying surfaces etc. in. However. over the last 50-60 years. This is really just a square. having the ease of condrag.. cut across the grain. or a small piece of stringer-thickness can be cemented former to the surface but also provides a slightly wider support for the covering at that point. Such wings are still to be found on ultra-light models flown indoors (although the ribs are cut from sheet balsa and the covering is very lightweight tissue or possibly microfilm) or.5mm) wide.the diamond.TRADITIONAL CONSTRUCTION Sheet balsa fuselage construction is often found witfi slim. This not only brings the being that its if the airflow is flat surface to not parallel with centre-line. single surface wings were common . bamboo not go too far into that! WINGS solid sheet wings on small models such as the glider in the last chapter or the Apart from little rubber-powered models that can be bought ready-to-fly. One other type of fuselage should be mentioned . wings have always consisted of a framework of ribs and spars covered by some light material. presenting a corner rather it results in reduced diamonds have proved very competitive and are thought by some to be a halfway stage between slabsiders and streamliners.the ribs were usually birch strip steamed to shape with a fabric covering on the top surface only. This each former. Naturally. completely symmetrical body turned on its corner. ply A and cut out to strip of balsa is form o mould or shadow. as would be expected. It Where best to pin the is mould down over a piece paper or plastic film. is probably offset by the whole wing working. where there are places where of the the former should reach the surface. this can be allowed for in its shape. improving the finished appearance and providing strength where needed. or ^A^n. The extra drag of the wires etc. in a superior envelope too. cementing the overlap as it goes. they con warp fairly easily and warps tend to have significant effects on how the model will fly. top many are so variables! Incidentally. The result and is a considerable increase in strength which can be further boosted for only a small weight penalty by webbing stiffness between the two spars with thin sheet panels between the ribs. in aero- dynamic language any surface capable of lifting is an aerofoil and its cross-section is an aerofoil section . reasonable thickness and being covered. one piece in tension and one in compression for up and down loads. A simple conventional wing will usually have a leading edge. Wash-out is most fore commonly used. one of the joys of modelling is that there usually with tissue. As you will gather. The region most likely to warp is where the wing is thinner.THE BASICS OF. saving the weight of wood and glue which otherwise would be used to sheet underneath.the same as wing section . Warping is used deliberately to produce particular flight patterns and expressions such as wash-in and wash-out will be encountered. that wing will lift more than the other. Full geodetic construction produces an excellent warp-free result but is complex and time-consuming. therefore. Packing is usually needed when constructing a wing since the leading edge on most sections is unlikely to be flat on the building board and it will. all of which have points for and against. a mainspar and a trailing edge. Wash-in is progressive increase in incidence angle towards the tip. There are wide differences in the actual wing section (rib shape) and spar arrangement. chord section is the overall front-to-back width of the wing. but it can subsequently be introduced or modified by the application of heat and/or damp. this gives a D-box which offers enormous will result grain vertical. Any subbe shallow because the section is thin and therefore sidiary spar must necessarily warp with the wing. sheeting in its the most crucial area. using likely to minimising diagonal ribs rather than (or as well as) and aft ones. i. Methods of warping include capping the ribs by sticking a thin strip top and bottom. and rigidity with the additional advantage of accurately maintaining the strength aerofoil section fact. so the model will be banked and will turn away from the washed-in tip. to slow down stalling (breakdown of lift) at the wingtip. so spars need to be arranged to minimise the chances of warping or to ensure that any warp that might occur will at least tend to beneficial effects rather than the reverse.but common usage now seems to use 'aerofoil' (airfoil in the USA) to mean the section shape rather than the whole surface. There might be a rear spar or subsidiary small relate to spars. and bottom. Further strength 30 from cutting the webs with the If the forward part of the wing is sheeted top and bottom between the leading edge and the mainspar. Larger wings bear larger loads but spars cannot be increased in size without incurring weight penalties. If the wing on one side of a model has wash-in. AEROMODELLING .this is likely to be at about onethird chord back. which also happens to be the largest unsupported area. Spar placing has to where the strength also how the covering is needed and the pull exerted by shrinkage of will affect the structure. the mainspar generally being placed at the point of greatest depth of the . one piece can be used on the bottom surface and the other immediately above it on the top. If instead of having one solid mainspar the same weight of wood can be split in two. washout is a decrease in angle. so methods of increasing structural efficiency must be employed. and so on. The slight angular changes needed are obtained by packing the appropriate part of the wing it is pinned down for the covering to be shrunk. require to be packed up into position with scraps of when . or using diagonal bracing between the ribs. turning them into I-section members. top surface only In will provide most of the advantages. Because wings are large thinnish areas and need to be kept light.e. TRADITIONAL CONSTRUCTION wood at regular intervals. aerofoil section is called The curve of on camber and underside, on most simple models, but on many thie flat is other models forms a hollow curve called undercamber. Usually there is a light spar at the highest point of the concave curve to help attach the covering, and this spar too will need to be packed into position during construction. With undercamber, the trailing edge member is unlikely to be flat on the board so the front edge of this will also need to be packed up. Leading and trailing edge timber is generally available pre-formed which saves a lot of awkward shaping. That said, one shape of leading edge cannot accurately fit a whole range of sections, so experts or perfectionists will shape their own. The trailing edge is less critical and, being thinner, is inclined to curve if sanded more on one face than the other so is generally bought ready-shaped. Ribs are usually cut from sheet balsa the favoured choice wing where every basic rib is rib is is and a constant chord the same size. If the traced onto thin ply, or even thin aluminium sheet, it can be used as a template to be laid on the balsa and cut round. Some modellers prefer to draw round it with a ballpoint pen, drawing all the ribs then cutting round all the lines. The result- be neatly stacked and pinned together (usually two pins pushed in from each side of the stack) and lightly sanded to match. Often it is best to leave ing ribs should then cutting the spar notches until this stage is reached, ensuring that the ends are flush then using a saw and file to cut the notches in the stack. Tapered wing ribs are more plates for the largest difficult. and the Tem- smallest rib (on the straight tapered section) should be then rectangles of sheet sandwiched between them, cut and sanded to match, followed by cutting the notches. The process should then be repeated with the templates reversed for the other wing half. The alternative is to plot each rib, or trace each one if they are all given on ihe drawing from which you are working. These latter remarks also apply to odd-shaped wings cut, such as ellipses or bird-type wings. It is sometimes possible to use the top outline of a template to produce different length ribs plus if the length is marked on the balsa, the I.e. and t.e. depths and the mainspar position and depth. The template can be swung to engage with these marks but not if there are great differences depth. Another approach is in length and to calculate the percentage length change and reproduce basic rib on an enlarging/reducing photocopier, which also has the advantage of being transferable onto balsa as previ- the ously outlined. At one time there was a vogue for 'sliced' where a separate top and bottom are used, both being of constant depth. A piece of sheet is cut to the chord width and the ribs, A simple wing on the building board. It uses a single mainspar and cut sheet tip and is part of the kit model shown on page 7. 31 THE BASICS OF AEROMODELLING ribs sliced off by moving a template down approximately Vsin. at a time. The slices can then be cut to length to fit a gently tapered planform. One result is that the overall depth of the ribs as a percentage of ribs against the the chord a much stronger will gradually increase as the chord decreases, but provided the taper not too great this may not be unacceptable. To build a wing, one flat panel at a time should be tackled. The suggestion 'build the wing flat, then crack and cement at is dihedral breaks' is common bound but misleading be a difference in length of spars depending on their positions. Imagine a wing y4in. thick built flat. When 'cracked' to, say 10 degrees dihedral angle, the top surface loses over Vain, in length, so since there if is to there are several spars they to will all require be different lengths. It is therefore better one panel and, when dry, prop it to build firmly in position at the correct angle and second panel onto it etc. An even better idea, where a reasonably deep mainspar is used, is to 'build' the spar first, complete with any dihedral braces specified, which will ensure correct angles as each panel is built to the spar. Care should be taken that the rib notches are a good fit on the spars. Too tight a fit on a lower spar will wedge the notch further open, distorting the ends of the ribs upward, too loose a fit will mean a bigger blob of cement or glue adding weight and also on drying, shrinking, pulling in the sides of the notch which forces the rib ends downwards. It is normal simply to butt the build the sure they because all this leading edge (but if it is substantial a shallow notch put a of the file same thickness as the rib joint. The trailing in with makes edge, being thinner and wider, is almost always notched to receive the ribs, except perhaps on smaller models. Take precautions against the structure becoming stuck to the plan, especially on long joints such as often occur between the trailing edge and a curved tip member cut from sheet. In many instances in larger models, the centre section ribs are reduced in depth to receive sheet covering (which brings them back up to normal depth) this surface, while the centre section flat on the board, a warp creeping is and should be partly carried out on the top to minimise the in. A warped is pinned chance of centre section not always easy to spot but has consider- able effect on show little A flight. of designers lot triangular gussets in stressed ends where they are thinnest, along the t.e. All of these can be areas or at the rib cemented in in the air, so to speak, but only one panel at a time and the cut ready, then panel pinned back down for approximately an hour. Gussets will be stiffer and stronger if the grain is parallel to the hypotenuse, cut as sketched. Always check the wing carefully, particujoints. Sand it well, particularly where the ribs meet the I.e. and t.e. If they project even slightly above or below, a wrinkle will appear in the subsequent coverlarly the ing. Try to blend everything using fine glasspaper. model look mance will in smoothly, Not only infinitely better but its will the perfor- be improved. Wing for a 60 in. bottom members Ribs are notched 32 make touch and are properly stuck) is usually fairly deep, although {] .5 m) power model using top and main and subsidiary spar. for both into both I.e. and t.e. TRADITIONAL CONSTRUCTION Fig. 4.2 Z. Cut from sheet thus SURFACES TAIL UNDERCARRIAGES In essence, these may be treated as small wings but, as they are smaller, lighter and thinner than wings, it is even more important There are really only two materials used on the average u/c - piano wire and bamboo. Most small models with a u/c have a simple to ensure that they are warp-free. wire one fixed in two sheets possibly they may have Quite symmetrical sections, meaning that both leading and trailing edges need to be packed off the building board. Where a movable control surface narrow vertically across the Wire is between cemented place, frequently balsa of bottom of the fuselage. also used for larger models, but bamboo may also be used and the u/c legs built are usually detachable, plugging into tubes example a rudder or trim tab on a best to build the whole thing as one piece and cut through outlines etc. to free again are usually found with fixed wire the tab. For free flight, the tab (or rudder) to for in, fin, is is it is likely to which require to be set to on angle hold permanently once and a 'hinge' of aluminium, soft iron or copper wire is used, normally just two short pieces pushed and cemented it will established into holes pierced appropriately in the An meet- two tiny pieces of thin aluminium sheet cut from a drinks can or something similar, cemented into slits made by a sharply pointed knife-blade. The tab is bent as necessary during trimming and lightly secured with cement when the ing edges. required angle alternative is is found. Flexible hinges for bound into the fuselage. undercarriages, the wire(s) being secured one or more ply bulkheads either or small plastic saddles bolted over the wire. Often the spring a single cantilever in adequate, although for larger and heavier models a double leg each side is common, the wires being wire leg each side brought together with is just above the axle, bound wire or similar and soldered florists' together. for detachable legs ore The tubes used usually of brass but depending on the may be size or wrapping with a tissue being rubbed model, held in aluminium, and weight hinges con be purchased. 4.3 by sewing through pre-drilled holes with strong thread or thin wire or by means of J-bolts mobile controls can be made from tape or sewn thread as sketched or proprietary Fig. Power models of the place by binding or sewing, in, strip, cement then or secured to a sheet part -^ Topes (in pairs) .-)^^-' -Q,Ci- ^1^ A / A / •.,v.oK'.;-) <^. t \ V 33 THE BASICS OF. one at the bottom. Fixing the first washer is easy with no wheel present. The paper can then be torn away and oil introduced to counter any flux that may have run along the axle and might later cause the wheel to ^ Clothes pegs make useful clamps. In the case of detachable cantilever bamboo into may simply plug straight wound gummed paper tubes legs they card or appropriate angle in the body. but twisting in in bamboo by fairly may binding with order to prevent it from it must either be the binding doubled back for a short distance. the end turned over and cut off short. and a wire spring against which they can pivot. Here a dihedral joint is being made. a piece of wet newspaper should be laid over it. the pegs applying pressure to braces while the cement dries. exiting through sheet balsa panels and firmly set at the cemented Bamboo to a strong point at the top. body of the with a silk or nylon patch cemented over and further cement rubbed in. legs may have a wire L at the top to plug into a horizontal tube. This is common on vintage models.. the washer slipped on and the soldering carried out quickly with a very hot iron. or the end of the wire flattened on some sort of anvil heating the short this with bit to hammer blows. the top of which also plugs into a tube. locating hole burned in the bamboo with in a a hot needle. but once the wheel is on. to provide an axle. be flattened makes quite easy. The wire be attached to the thread. Wheels are best held between tiny washers soldered to the axle. AEROMODELLING Diagonally-set ribs forming a Warren girder type structure are often used on tailplanes because they tend to reduce warping. 34 .. They can. Two circles cut from balsa sheet and cemented cross-grain form the basis. One other form of undercarriage may be seen. It is 4.4 possible to use tiny curls of thin copper wire instead of washers or. but it is easier to cement them each side of a thin ply disc. bent from sheet duralumin or similar alloy and either bolted to a ply platform on the bottom of the fuselage or held in place by strong rubber bands.. Quite serviceable and attractive wheels can be made in this way. For very small models. TRADITIONAL CONSTRUCTION Fig. be sanded by hand. This (or a 35 . If a compass is used to mark them out the centre hole can be opened out and a lOBA bolt passed through can then be held in a hand-drill chuck power drill if you are very careful) and glasspaper held against each side in turn. of course. collets or screw-spring wheel retainers can be bought. for larger diameter axles. roughen the end of the axle and put a turn or two of cotton in place with a little blob of cement. seize. Axles on such undercarriages are high-quality hardened steel machine screws. The wheels themselves can be bought although for rubber models it is not difficult to make a pair. Cement a stub of aluminium or brass tube in the centre hole and check the alignment. Alternatively balsa cement with acetone and paint this on the wood. white photopastes such as Gripfix or to water-thinned white PVA glue. Adhesive is only applied to the area being covered unless there is concavity.this must be spread on the frame and then rubbed over with a finger since any small blob will make which is the tissue soggy handle. hard. A the wood grain panel of tissue is is laid in well fairly place and cellulose thinners brushed over the previ- ously doped areas. When dry the component is lightly sprayed with water and pinned (with weights or angledover pins) to the building board to dry and shrink. available in when handled. Again only available from specialist suppliers. is the tissue. The same and therefore difficult to applies to thick wallpaper paste and.e. Rag it tissues are more fairly heavy agglomerations of random fibres. Modelspan is available in lightweight or heavyweight grades. You may encounter these at a model shop. has no ably well in all many colours. also helps to seal against fuel It absorption. The majority of it's models are tissue covered and most R/C models seem to use iron-on plastic film. to a lesser extent. Hard tissue is light in weight. it can be distinga classic lightweight tissue. as in the case of undercambered ribs. Tissue paste is also available . usually only white but occasionally a batch of in colours comes through. shrinks reason- directions but unfortunately does not possess great strength and quite often fades within a few months. Modelspan and rag-type. It will in but not easily also tend to shrink across the grain. through thinners etc. balsa are primarily to achieve a without a vast increase in good finish weight and to toughen the surface against dents and scores. Adhesives for tissues are very much a case of what suits you best. i.CHAPTER FIVE Covering and finishing Covering seems but to others to come naturally to some a chore. uished by the fact that will has a grain - it tear along the grain across it. Jap is almost any colour. from Japan. both of which are quite widely used. then paint through the tissue with neat acetone. they can be heavy but they will are also strong. Condenser and has a tissue is creamy. tend towards The reasons for tissue-covering sheet tissue. Clear proof the dope is then applied to air- you can thin tissue. rustles grain. semi-transparent satin shine. lightweight it is used only on very and models indoor is only available from specialist suppliers. the remainder employing nylon or. shrink in all directions but absorb a lot of dope. when adhesive has to outside edge of the . condenser. while the heavyweight should only be used power models and large gliders. The allowed to dry and the panel trimmed and the edges doped down. giving several coats until filled. Tissues are available in a range of choices and references may be seen to Jap. it is widely available and used on small/ light 36 models. This is probably the easiest lighter tissue to use. to a decreasing degree on the grounds of cost. Many of the for best builders clear dope the contacting sur- faces of the balsa airframe. It is possible to buy tissue cement in tubes spread directly on the frame. The lightweight is heavier than Jap or hard and takes more dope to fill the pores so it is not ideal for smaller models. silk. Open-frame control-line models free-flight among are probably equally divided the three material groups but solid sheet v/ings and planked fuselages etc. However. shrinking well in and providing reasonable directions all strength. 5. Gently extend the tissue to the centre of the tip and press lightly onto the adhesive. Tissue has a very limited ability to cover two-way curves without wrinkling so it may be necessary to cover a streamlined stringered fuselage. a grain) and apply the adhesive along I. evenly and smoothly. Should the wing hove undercomber the procedure is similar but curve the tissue panel in your fingers as you first place it so (a others. allowing an inch or so extra all round for handling. or a turtle-deck. Sheet areas should be clear doped. A slabsider fuselage up to 30in. need twelve strips of tissue.e. then work the thumbs along the tissue panel to the I. and press to tack down.e. overlapping only slightly an angle. a it is lift it off the You could also run dope little it is making a is covered a messy business.1 in strips A it drops onto the ribs first. then bottom and top or alternatively bottom. If it should come fuselage. The usual procedure is to cut as large a panel as possible. Follow the aforementioned procedure but pay attention to each rib and do not tension the tissue that undercomber. Fig. finishing on a cross-member. Once should covering is be damped by completed the tissue lightly water spraying 37 . Always cover the undersides of the wings first. then add down the second portion. around the outline. the upper surfaces of the wings and centre-section plus two separate tip panels (5).e. For square fuselages you con either cover both sides.e. Reverse the wing and work back towards the root rib in the same way.COVERING AND FINISHING be applied to each concave member. Make sure all the edges are stuck before trimming surplus tissue away. cut the panel (grain along the span if there restoring do rather than try to is it in large panels. Moke enough to circular fuselage with twelve stringers will sure firmly attached. although sometimes it con be done with six. root rib and tip. If you try to stick it around the edge. Now spread the centre of the and t. gently smoothing the tissue and It is just putting a little tension on it at not necessary to try to stretch apply it it tout. rather than sheet panels let in at the fuselage nose.e. You can try line of pinholes through the tissue along the rib centre line and rubbing cement through. sides then top. making sure that double-edged razor blade is again useful) leave enough overhang to paste down and round so that the top tissue will meet it and overlap it fractionally. a conventional wing with centre-section probably in eight . (760mm) long can be covered in four panels. but on the cross-member. This applies in the main to larger areas such as sheeting on wing leading edges. is stuck. Lay the tissue lightly in place and press to the centre of the root rib the (brush thinners at this point if using the dope method). i. and t. unstuck on shrinking after the top Taking a wing underside as an example.the undersides of each wing panel and centre-section (3). pinning the tissue to the rib while it would be to two-bay panel and patch in new dries but a better alternative cut out a tissue. depending on the type of tissue and the curve of the along each rib so that subsequent water spraying will not get through to the adhesive. tissue laid over the wet dope and a further coot applied. sheeted fuselages etc.. is If the tissue too short cover with the longer panel first. water-shrinking then doping con still leave wrinkles as the tissue expands slightly with the wet dope and the dope soaks through and sticks in when trimming some places but not edges. especially if there Stages in wing covering Separate lip piece under- is camber. later. blotted in between sheets and pinned in of newspaper place while adhesive is ap- The frame-doping method. the tissue is not is and (or steaming) and and toil it left to dry out. In fact most of the adhesives mentioned can be used bearing in mind that there would be no point in using silk plied. Wings should be weighted or pinned may pay to down cover the building board damp fully when dope when conditions or dry to start with shows as white opaque patches doped area. Do not use large areas of colour dope as it is very heavy. heat-shrinking. blushing Most reputable model shops offer clear shrinking dope or clear non-shrinking. It resembles a thin clear varnish and is a little heavier than dope but it does not blush as easily. Model enamels are.or car spray cans can be used to dust on the colour. The idea behind this method is that the tissue becomes puncture proof and the whole model is stronger for an infinitesimal increase in weight. selection of rubber models and one glider using bright-coloured tissue finishes and no colour dope. It will disappear all if smoothly with greaseproof paper. either when doped. but disappears previous uneven damping. plastering it with colour Use coloured tissue or. AEROMODELLING . Banana oil is a form of cellulose lacquer which has no shrinking effect but it will airproof and. then coating with will is stop shrinking when sufficient resistance met. The blushing disappears when painted with thinners or dope. waterproof tissue. mix a little fabric dye in the water to be used for spraying on to water-shrink. to some extent. some little local may be evident and it is worth wetting these After drying in case they are the result of Some tissue is applied experts in dampen swabbed when a drier conditions. cement rubbed on with the finger and acetone painted through the cloth. Both types of clear dope fulfil the most important function which is to fill the pores in the tissue and render it airproof. The when or dope is applied. . Obviously close-woven tissue will require less dope to do this and the end result will be lighter. then soaked in water. much lighter. a process which does not destroy its shrinking ability but which adds a degree of elasticity so that it supplier). or 'straight' PVA can all be used. kitchen gently with cellulose thinners or or thin polythene sheet (perhaps an exdry cleaner's bag?) so that the tissue does further coat film not stick. Foreground model is a competition design using a A single-blade folding propeller. The technique of covering the panel with very former will help to reduce some wrinkles but too powerful a shrink will tend to distort any but really stiff. wrinkles from the water or. It can be 'plasticised' by adding a few drops of castor oil and stirring well. Even more occurs when using a recent new is extensive. strong structures. surprisingly. usually using the doping blushing thinners method and over the when of adhesion. If no spray is available it can be smoothed on gently with if a wad of cotton wool. their panels of before applying them. you want a particular shade. to keep light it defeats and this object.THE BASICS OF. Wet for silk application is usually recommended or nylon covering. the cloth being allowed to drip. If a model is tissue covered one aim must be 38 thin mylar film (using adhesive from the film clear dope onto which is laid wet tissue. Blushing occurs applied in cold. The film is then eased evenly over the area. a ability. although speciallymade irons are available and are worth buying if a lot of film-covered models are to be made. the material can always be lightly sprayed with water during attachment. and the heat Too cool an on film-covered models is usually carried out with further film applied over the basic colour or by specially produced paints. one-pot thin and. too so experiment film. not quite will cause the iron will fail in contact. Panels are then cut. but these films do not normally wrinkles with add a great deal of torsional stiffness or On the other hand. The surplus is then trimmed away and the trimmed edges stuck down. but water will not shrink it. A domestic iron provides the necessary heat source. or.COVERING AND FINISHING nylon on an insubstantial especially. others need the framework outlined with a special fluid which dries into the surface and bonds with the film backing. Some have an adhesive backing which will stick directly to bare wood on the application of heat. These are used only in the vicinity of the engine as they are fairly heavy. can be stuck round curved parts without just a little care and some practice. Different films also glow or react differently to diesel fuel so there are also special fuel-proofing varnishes available. again on the application of heat. Unfor- tunately appear is fillers in in the dope cause cracks the finish after a few weeks. tacking in places. for a that power model. so necessary to keep applying plain dope until result seen that the pores are is it is filled. Nylon in particular is likely to need several coats of dope to fill the pores but it doesn't really shrink much from the dry state. The iron is now passed over the it actually is . out. since two experi- matter of natural 39 . The manufacturer usually supplies helpful leaflets with the film. depending on the type of film. to some extent. ensure to film hot an iron can melt the first The more open the weave the more likely strength to the structure. It probably sounds more complex and largest expensive than Film coverings are available in a wide variety from those resembling tissue cover- heavyweight types suitable for the models. giving plenty of working time. as for tissue. and the centre of one end tacked in place by touching lightly with the nose of the iron. frame so it is makers' pins quite feasible to use dress- hold the cloth to in place. Decoration to it adherence. except possibly. The basic method is first to paint all areas of the frame to which the film is to be applied with the preparation sold by the film supplier. from glow fuel. contract- fibres them- selves are not physically affected. A good ing to model shop should be able to advise you on choice of film and the necessary ancillary items. polyurethane varnish two-pot polyurethane varnish. either raw or exhaust residue. Fuel-proofer applied to prevent is oil soakage into the structure and to prevent some components in of the fuel. FINISH A good finish must be. The extremely strong and the standard joke of having a nylon following a bag bad crash has full its of balsa bits basis in fact. It tends to expand with water which is why it is applied wet. if he recommends this for the film you have chosen. Should it dry surface. Film coverings should use the proofer developed and recommended by the manufacturer. from attacking a doped Commercial proofers are available but a reasonable degree of protection from diesel fuel can be obtained or painted with finish.remember once the film is in place there is no outlay on dopes etc. fuel-proofer which would be needed whatever covering is used. and ironed along all edges etc. little harder to persuade round compound curves. pieces of film that have been with when cutting out the required Some films shrink considerably and discarded panels. film to shrink. since those that do are often a it that clear is shrinkage ing relies dope will tauten on the dope between the fibres itself and the it. Small areas of coloured tissue can be doped on to provide a decor. have been worked out. Care in assembly and thorough sanding have already been stressed. Clear dopes have been dealt with and mention made of using model enamels in preference to colour dope from the weight aspect. or talcum powder can be added to clear non-shrinking dope. Using transfers (decals) is not recommended on small models or on unsupported tissue surfaces. It is applied freely with a brush.) these can be painted with enamels but not with cellulose unless 40 a special 'dry dusting' spraying is used. sufficient to provide a non-patchy colour. Should there be any polystyrene mouldings (some kits have vacuum-formed cowlings etc. plain-looking model which flies well is infinitely preferable to a coloured and decorated heavyweight which staggers into the air and breaks because of its weight on landing! . Colour finishes should always be used sparingly because the pigments are quite heavy. only a very thin coat. has been outlined.. Felt pens can be used to add a colour with negligible weight. If you look at any full-size aircraft in normal light at a distance of 50m or so you will see it does technique appear glittery. leaving the grain filled and the balsa surface smooth and slightly hardened against nicks.THE BASICS OF. cutting out the shape(s) with a new blade and attaching by lightly wetting the area to be covered with non-shrink dope. preferred by most expert modellers. at least until you have gained some practical experience. then fine glasspaper is used to sand virtually all of it away. AEROMODELLING enced modellers can use the same materials and techniques but produce widely different results. and the application of tissue etc. It should be mentioned that while enamels can be applied over a doped (cellulose) surface. The sealer can be bought. with practice and patience a good. so much the better. A light. pressing the tissue shape lightly in place then doping over the shape once wrinkles etc. allowed to dry. cellulose finishes cannot be used over enamel. However.. pleasing finish can be obtained. It is still best to cover it with tissue rather than try to colour the area with dope or enamel. by the doping methods. should be used and if it does not dry to a gloss. Models recommended not for beginners should remain tissue-coloured and clear doped. but take on doped may little not surfaces depending on the solvent used in the colour. Filling wood grain with sanding sealer is another requirement notably in sheeted areas. the classic test glide into long grass should be followed. A stall occurs when the airflow over the wing breaks down. glide trim is not achieve. usually because of loss of speed. hand if If built accurately the incidence angles should be balance is a as specified. weight. the Centre of Lift. Thrust has been replaced by the forward horizontal component of force generated by weight influenced by the aerodynamics of the model. (15m) ahead. if possible. most probably. cures are nose. So we must first establish the best although if is it is glide condition and. (b) This (a) is stalling flight and the increase the weight in the decrease the wing incidence by Fig. the point at which you would tie a string to hang the model exactly balanced. leading to a high-speed stall and. from the ground level it is going up. in order to avoid a hole behind the wing. nose drop. pointing on the ground around 50ft. thrust and drag acting on a model. too fast will produce a swoop usually followed by a stall. The second aim. 6. Thrust. Bernoulli's Law. rubber or towline) arrange a stable set-up without disturbing the glide trim. In a glide glide trim since once the model glider its always moving downward in air rising faster than the model is descending.1 Smoo' 41 . launched slightly nose-down. the nose drop and a dive ensue. Nevertheless. All the is lift any model flying free is a power runs out. and the first to be tackled. For a more technical explanation look up generated by a wing acts through one point. Therefore.CHAPTER SrX Trimming and flying An provides aircraft lift when moved because the distance over the top of the wing is further than the distance underneath. just as all the weight of the aircraft acts through the Centre of Gravity. While Lift and Drag are still present. One aim of trimming is to balance the four forces . difficult to wing and tail correct so. and the force trying to hold it back. when thrust is added (engine. a too rapid change of attitude can cause the airflow to break away at any speed. Then there is the force driving the plane forward. Provided a model balances where indicated by the designer. a flick half-roll and dive. the model dropping out of the air.lift. followed by climb. glide should be safe. Long grass cushions the arrival of the model and goes some way towards reducing damage in the event of a mishap. the air through the air across the top has to move faster and this reduces the pressure on the top of the wing. and at about the right speed. as initially the speed required may not be judged too well . weight would normally have a vertical component only but the shape of the model modifies its motion.too slow a launch will lead to an immediate stall. the model may climb. dive If at a spot and so on. However. Drag. worked up as it even when full to slowly. Air resistance does not hold the propeller still but it does have a braking effect on it and this effect is passed to the model. This can be caused by warps or misalignment of the surfaces and the effect may be heightened with increase in speed under power. the trim already only feasible adjustment. the reverse steps apply . try glider except a will longer to settle. may not. safe trim is when the wing is always at a slightly greater (positive) angle of incidence to that of the tailplane.THE BASICS OF. . it flights for a stiff a glider is on a line passing through the centre of gravity at an angle of 60 degrees to the horizontal. effect it results in the Left-handed props are normally seen only on twin-engined or pusher type models. This and is called torque model turning to the left. you wound a rubber model then held and let go of the rest. giving it a tendency to rotate in the opposite direcIf the prop tion to the propeller. .(a) reduce the weight at the nose or add weight to the tail. except possibly by small rudder to glide. so in this instance nose ballast may be the Having reached a reasonable gliding a sloping if possible a longer glide. AEROMODELLING packing balsa strip(s) under the trailing edge. This applies to a right-handed prop (turns anti-clockwise when viewed from the front) as well as engine-powered models.which forces already balanced any modifies the the glide. so it is seem although with a high-powered model first establish what is causing the and remedy or counteract it. which give the model a little large circles in fine tuning to little produce while maintaining a flight tow and perhaps tiny changes in nose ballast to achieve a floating glide straight without undulations.the a further dimension power thrust line . This whether the model is turning one way or the other. (b) increase the wing incidence. you would not be surprised if the whole model rotated. wait until short flights thrust line. If are made but Any change in the glide trim produced by the power line of thrust should be cancelled only by the changes in that adjustments. The model is already climbing and torque effect is banking it left. With rubber or engine-powered models is added once a satisfactory glide has been achieved . One obvious J 42 cure A is to apply right rudder. With a powerful motor the torque effect may well cause the model to turn and dive into the ground on the left. The usual hook position on release. In the case of a stall where the wing cannot be moved. beware of reducing the angular difference between the wing and the tail too much. . (c) increase the tailplane incidence by packing under the leading edge or (d) move the whole wing back if the design permits this. and watch Tow carefully gently it initially what happens on goes without saying that test trimming should not take place in breeze. If the model glides very steeply or dives. but this will — nice launch by a young lady note the followthrough of the hand. angle. Since in successful flight will require the model found should not be altered. (c) decrease the tail incidence or (d) move the wing forward. field down or from a hillock. Only ever alter one thing at a time and only by a small amount at a time. There is else to be done in the case of a towline desirable to find out turn little there is power is always a is not as difficult slight risk. you can have dead air. (3mm) on a 36in. or poor air in which a model glides strations down well. causing the model to bank. or the over a foreshortened span if the design incorporates sweepback. or fly this of expert techniques. good where quickly. and may quite possibly experience a touch of up-aileron effect opposing the bank. glides exceptionally and corresponding doesn't get heated by the sun but by conduction from contact with surfaces which are heated by the sun and it is this which sets up convection. buoyant air rising air or air it lift where it glides well. say Vsin. tending to help reduce the turn. This is one reason for aiming for wide circles! Dihedral angle — ing when V - of the wings helps in that on banklower wing is presented to the airstream at a more advantageous angle for its total span while the raised wing has a lower angle of attack over its span. However. placing thin washers under the lugs at the rear mounting holes. possibly the model to spiral rapidly down when the power runs out. the outside wing fractionally faster and therefore generates more lift than the inside wmg. Wash-out can be built in by propping the trailing edges at both wingtips while weighting the leading edges down during the period when the covering is shrinking. Another trimming aid is wash-out reduced incidence angle . With high-powered models having a tendency to line loop. model. thus producing a force which tends to roll the model out of its bank. increas- bank leads to sideslipping inwards. it. The answer here is to tilt the propeller shaft downward. and the nuts tightening. a little downthrust. a nose-up couple. but is entering the realms stall With a beginner's under power. However. (900mm) wing. Reducing the angle allows the mside wing to remain lifting longer by delaying the stall. will suffer Warps can often be taken out of flying warming them in front of an (with core) and pinning them surfaces by electric fire down. in order to ensure consistency. The difference between the heat absorbed and reflected into the air by. or holding until cool. it is rare for the thrust line to be higher than the centre of drag.at each wingtip. thus offsetting torque effect to a greater or lesser degree. If you have made the chuck glider in Chapter 3 you can hold it pointing towards you in a bank and see the difference in the wings. passes above If the thrust produce a nosedown couple.TRIMMING AND FLYING make the glide circles different. leaving a model exposed to hot sunshine can undo all your mini- by altering tensions in the covering. twisted the opposite way or even by re-doping. It 43 . a model turns. again by packing the noseblock or. Due to the drag generated by the wing and its usual position in an aerodynamic sense. wash-out can be induced into a panel. then re- The amount has to be a matter of experiment. which is in respect of the centre of of course fixed. Air is funny stuff . with an engine. and if below it. Only a small amount is needed. The other to its effect of the thrust line relates position drag. for descending air or sink. if the line of thrust is altered by pointing the propeller shaft a degree or two to the right. as if it in a if it tends to was going 'up little When travels stairs'. Increasing turn can cause the inside wing to stall. This alteration and called sidethrust is made on is a rubber model by packing the port side of the noseblock or on a power model by using bolts smaller than their holes. slackening twisting the engine. called downthrust. a sideways component of thrust is introduced which will turn the model ing even tight enough for the to the right. Some keen competitors mature their models for some months before fully trimming them. with rising and correspondingly sinking air currents. rather than will turn the incipient loop into a spiral climb. while the faster-moving outer wing increased drag. it is safer to put downthrust. In the same way. so in most cases motor power tends to create a nose-up tendency. it will extra sidethrust. the weathercock action of the fin turns the nose down and the model spiral dives into the ground. The eventual answer proved to be a simple arrangement of rubber bands immediately. If tinual stream. is example. In calm. Commercial winches are available from specialist suppliers. slightly may breeze he wards stand his assistant to or even run toreduce the model's still speed. or a cornfield and a considerable. The arrangement. AEROMODELLING The helper has just released the glider which is already climbing steeply. RUBBER WINDING The specified (or appropriate) length of rubber should be tied into a loop with a reef knot and an assistant should stretch the knot and ends while half a dozen turns of knitting wool are tied tightly. taking with them any models which have flown into them and remain circling within them. Note the pennant attached to the towline. can also be triggered by a clockwork timer mechanism for a small weight penalty. moving forward with the flier. Wash the rubber to remove any dust or . but rise in a con- fhermals when activated. released the tailplane to pop up to a negative angle of which. The flier holds the line to hang in a slight loop which will hang vertical when he is directly into wind. pointing into the wind. GLIDER Ideally 44 TOWING an assistant is needed and a winch nose-up. called a dethermaliser or DT. in a brisk in it should start to veer. a gentle if it is required veers sharply the line should be slackened to release the ring from the hook. a factory building and o grass field. He then moves to take up the slack. even to the extent of throwing the winch towards the model! A light pennant about 6in. Hook the loop on a doorknob and measure off to make the requisite number of strands.THE BASICS OF. but nevertheless a name and address should always be marked on every model. a means was sought of ending the flight without damaging the model. the flier will probably have to run to start the model climbing. It is a refinement which the beginner probably need not worry about at first. The winch can be a drum on a hand-drill. (150mm) square near the ring will help to blow it off the hook. signals and walks or trots into the wind. eases his grip to allow the model to rise out of his hand. about 30 degrees. or made from Meccano or from a hand-grinding device made to clamp on a bench. These are generally called pull the opposite direction and they can be very strong. giving of air which break rise to wood or lake is warmed bubbles away and The assistant holds the model helpful. As models became more efficient and a greater number were lost. slow up and allow the model to settle at the top of the climb before releasing all tension. these used to be sold in chain stores and come up surprisingly often at car boot sales or on used tool market stalls. With a straight tow. As the pull comes on the model the assistant. Secure the ends by looping rubber bands tightly round. release was (and is) usually by a length of smouldering lamp wick which melts the key retaining band when it burns down to it. . close against the knot each side. accelerating as they rise and travelling downwind at wind speed. completely wing and causing the model vertically in a horizontal stalling the to descend The attitude. and hooks on the towline ring. Dethermaliser the loop formed on sleeving these fingers so that Fig. protect the wire from discarded cycle valve rubber etc. in place by a stout wire between two strong lugs and through an aluminium tube on the model used in place of the rear motor dowel. If in difficulty seek help from an experienced modeller.) or castor Do oil. then 350. undo one end of the and halve the strands approximately. though little trouble should be encountered if the manufacturer's instructions are followed and fresh fuel used. but these methods are really only used by keen the fuselage. Another competitors anxious to wind their models to the limit for each flight. On release. which slows it down. POWER MODELS There is a knack to starting most model engines and this should be practised thor- oughly on a test bench before installing the motor and rushing off to the flying field. Stretchwinding allows more energy to be stored in the rubber so that more power is delivered out. which will allow a four-stroke. it in in no loop. capable of positioning which and supporting the model. The more running-in an engine has the easier it 45 . thus allowing the chance to trim the model without going off at full bore. silicone lubricant (for car fanbelts etc. at least three times length. An model. a wire hook securely the propshaft. winding on turns as its it is unwound stretched winding back in until it is close to the fuselage nose on the final turns. ideally with a and thumb ahead of and touching the dowel. It should be stretched while winding. contact with not allow or dust dirt by storing light a clean in come to it and keep it Actuating bond a cool in tin into from place. next time 200. having removed the prop assembly which has to be replaced on the wound motor. securely fastened to the ground. A rubber motor should be broken in by first winding 1 00 turns. drill fix and engage rubber electrical flex. with in the is allows single-handed winding. marking the centre with a wisp of wool. two-stroke engine to a difference which can easily be heard. and hook directly to the motor. two fingers should cross the nose aperture and the motor passes between finger it is not chafed. then for longer. dry carefully with a clean soft cloth and rubber lubricant lubricate with purpose-made (specialist suppliers). This is i<. grasp the centre skein and realign the ends. Wind on about 50 turns. which reduces its efficiency. surrounding the motor so that if it breaks it will not destroy method is to wind outside the fuselage and use a rod to pass the wound motor into the fuselage. This is passing retained 6. the motor will coil itself to a shorter length. For initial flights the motor can be run rich. and the other hand holding the nose. Running rich simply means opening the fuel needle-valve. Retaining Adjust turns the final until length distance between the hooks To wind. To braid a motor. remove tube' the noseblock down Some and pass a fliers 'blast the fuselage. and/or the propeller can be fitted back to front. a hand- If assistant holds the band melted by fuse the model.TRIMMING AND FLYING chalk residue. to a frame. Modern practice in many instances use a 'stooge' for winding. resting for at least a few minutes between winds.2 . 34 40 29 33 31 36 31 APPROX WEIGHT OF RUBBER YARDS FEET PER POUND PER OUNCE 20 22 24 75 14 - - - 96 24 24 27 - - - 23 21 - 30 29 25 28 24 26 100 130 135 18 19 24 18 - 26 25 »fii. A glow engine has only a needle-valve control. pops as the prop too A little fuel.THE BASICS OF . especially with a diesel. so that unless a motor is made up and tested to destruction it is impossible to be certain of how many turns it will take or how much torque it will deliver These figures can only be used as a rough guide! TURNS PER INCH FOR A LUBRICATED. which need a paraffin/castor/ether mix. as does a discharged battery in the case of glow motors. important to use the right fuel model shop manufacturer's if . so if the plug is glowing and fuel is getting through. even from batch to batch of the same type. Lever Runs on would give ignition advance/retard.ask you do not have the Many instructions.x ^0 Vi( X *i. Stale fuel makes starting very difficult. (2. not suitable for diesels. 30 33 35 37 44 26 30 32 24 28 29 22 26 27 20 25 26 28 VX Vjo HxVi. show virtually the same engine design except that that on the left uses a glowplug and that on the right note the difference in the cylinder heads. The glow engine also has a simple cylindrical silencer rather a diesel than a 'straight-through' exhaust. AEROMODELLING RUBBER MOTORS Rubber varies considerably.x%. 1. and tiny tank perhaps two-minute run! 46 Occasional probably means fire. vintage '60' installed in must it is while too much lOcc petrol (spark an 8 ft. r/iese pictures — is will be It is at a to start and control. flicked visible . small glow engines will not run on 'straight' fuel but need a percentage of nitro-methane added to the basic This fuel is methanol/castor mix. RUN-IN MOTOR NUMBER OF STRANDS SIZE INCHES 8 10 12 14 16 1.5 m) behind propeller petrol/oil mixture is fuel may ignition) pro- engine free flight model. is transferred compression gradually increasing compression to the cylinder.so a duce a sizzling Diesels needed be able to recognise which control needs to be moved to get the engine running well. 47 . The quickest way to establish settings is to choke the little experience is to engine (turning the prop with a finger over air intake) and flick the prop until the resistance is felt as excess fuel and flick.the needlevalve and compression adjustment . then back off it fires. lead and "glowplug clip. You will soon acquire the knack of flicking the propeller hard and until fast and getting the controls correctly set. It will then either flood (close needle a little) or require choking again (open needle a little). hove the advantage that they do not need a heavy starter battery. but on the other hand they have two variable controls .TRIMMING AND FLYING sound and a flooded engine. The differences are only slight but it is best to be clear from laid on the sides board with the hllet strips cemented and temporarily pinned. all the is also straight manages lines decoration but the model to look attractive (see the still cover of this book). Trim off one A-A and one B-B and overlay the pieces accurately . again with the rule. Leave yi6in.) plus a length of sq. so you can either build three times over one copy or make three copies. For the fuselage fillets three quite soft Vitin. The fuselage building 48 .. Other odds and ends may be found in the house e. (2mm) diameter. sticking them accurately together. The materials required are very simple. and one of Ve x y4in. the square line using a yi6in. Lay the sides flat. ensuring one left and one right. square. mostly '/i6in. sheet and '/i6in. and pin and cement the '/i6 square round the edges. You will need two '/i6 X 3 X 36in. to obtain the second side. soft enough to mark quite deeply with a thumbnail. a paper clip and a scrap of acetate sheet for reinforcement areas. It Vi6in. Note that it is all straight lines. (or two would be if you could obtain a (6mm) balsa or a small block. alternatively a tracing could be made. sheets of softish balsa {^V2 x 75 x 900mm). then lay the piece over the remainder of the sheet and cut round. both medium to soft. and one '/i6 x Vein. Apart from a black even. tailplane and 13 wing ribs. The only other curves arise if you make the rubber-powered model and make a propeller. Use a scrap of glue All helpful y4in. cut At this point it is desirable to decide whether the model is to be glider only. tissue (or felt pen) cabin. if the two. or adhesive tape to secure them.g. First draw the fuselage side on one balsa sheet. but there are ways round this. The best way to build is to photocopy the pages of drawings and cut the three parts of the fuselage. Note that there is no fillet right at the tail end. rubber only or convertible. as convertible between It is intended that the pages should be photocopied to provide a plan. the blades of which have curved outlines. following the centre of the three lines round the the top dashed out outline. (The outside line and bottom sheeting. Don't cut them to the outline but just separate areas of paper. to dry.CHAPTER SEVEN Thumbelina This little model can be towline glider or with built as either a rubber power or you wish. It should be light but firm.) similar Cut metal straight edge. apart from the upper line of the wing section and the corners of the flying surfaces which have a tiny curve sanded in. out the While you are waiting you can fin.the straight lines top and bottom should make line-up easy. stick three wing panels are the same in plan. square are required and for the wing spars three lengths of fairly hard '/i6 sq. a bamboo skewer (for kebabs) about %?in. steel rule or shows the inside fillets. Alternatively you could buy a plastic prop from a model shop. Trace to a piece of thick card or You can use this as a draw round 13 times or cut out. spars can be model but if the wing spars. template either to construction (except for the actually to guide the blade to cut out the spar and addition of Assemble the ribs into a stack. Gl. If glider-only. which means cutting those notches deeper. the outset. follow rubber change of wing towhook) but there through and solder strip as necessary for nose weight. one can be laminated from spare '/i6in. cut two y4in. Far picture. cemented in place then. and together fit across the fuselage as shown. back to cutting the the rib shape on thin ply built OS fitted and wing ribs. The three '/lein. a plastic ruler to hold things square. Assembling the fuselage sides using. for the centre one of the three. aligning the flat bottoms and leading edges. then cut a former.6in. 49 . wide strips of '/i6in. If If a convertible.THUMBELINA Simple structure still requires care to get everything square and true. Nose is rubber-banded and scrap piece checks alignment of tail slots. back from the nose. and cemented to the nose. Now. about 2in. A small groove cut or filed across the noseblock band and the block will will locate the be held firmly in place. round the noseblock and back to the other end of the bamboo. piece of nylon tights cemented over the flat area. square for the rubber either of the other versions is x Vein. when sheet reinforced by a postage-stamp size dry. Cover the hole with tape for tests and cement a plug in when satisfied. is screw or bolt in wound round or lead shot. from when assembling the sides '/. and push two pins through. first piece of underside sheeting and nose reinforce- ment strips. First. a further length of bamboo is cemented through the bottom of the fuselage sides. Drill a hole in the top and drop slivers of lead. This forms a box when the top and bottom sheeting added. The towhook can be bent from a straightened paper clip. to balance. in this case. sheet and cement to chosen use '/i6 the fuselage sides inside the nose ends. A noseblock as shown would look attractive but to save buying a block. or a pack of balsa offcuts. Lightly sand so that will hove to be an alternative noseblock box firmly built onto its back or a with a ribs. a rubber band con be stretched from one side. AEROMODELLINC .THE BASICS OF. . THUMBELINA 51 . diameter. Place it Top. as cut. The fuselage is iy2in.e. they can be slightly bent and removed once the top or bottom of the fuselage has been sheeted. squeeze in cement and lift each tip 2 in. (38mm) wide beneath the wing I. blocking in place Fit dry. and t. and t. which means a l%in. then mark the notches for the spars across To make things easier.e.e. and t. dry. pinned together for sanding.e. leave to add gussets and re-cement joints at the dihedral breaks.e. the sides can be propped Vuin. Bottom. positions. can be pinned down and the ribs cemented in with everything flat. then spar books or parallel pieces of with wood. hold it for a few seconds in steam from a kettle spout. the leading and trailing edge strips pinned down and the four hardest ribs cemented at dihedral breaks and tips. the I. the sanded ribs with spar notches marked. wide. the wing ribs. ends can be drawn together and cemented and the nose ends drawn in and y4in.e. the wing has been designed so that added and small V cuts made in the I. fillets. and t. The centre panel spars are then the stack and cut out.e.e. Sight along the fuselage to make sure that the sides form symmetrical curves. against it If (or them) while four cross-pieces (or spacers) are inserted at the When I. at the dihedral breaks. or two small cans or bottles iy4in. gap allowing for '/i6in. spacers cemented in to make the nose Tin. and. AEROMODELLINC all the ribs are smooth and the same size.THE BASICS OF . if you draw (or photocopy) the three panels as one piece. the outer panel spars. 52 .. sheet with the front bottom in contact and gently easing as it to it cools. dry the tail symmetry then holding on the remaining '/i6in. lightly and round the When t. carefully sand the sections shown and I. (50mm). If one is straighter than the other.e. wide overall. An alternative is to cut rectangles from cerealpacket card and assemble the sides using these to hold things square. centre. Crack the bottoms of the V cuts. to the off the tips.e. sides and you can find a block or box l%in. / / — O _ 3 >c i X -S >^ X 1 1 Propeller iC blodes .THUMBELINA \ 4) ' 3 -D i -.4 from Ai" >c iC Prop section (see note) Hub o a> -D 1 X £ ^^ \ O X — *^ : i:5 / Pawl Freewheel 53 . or ^lain. with ing sealer. This should be vv'hen dry. Mark accurately and cut the slot in the fuselage for the fin tongue and check the tailplane slots for alignment. Cut the fin and tailplane and sand the edges. (3mm) bamboo skewer. the and fin tailplane in Cement place and lay a ruler across the wing seat. Add any required trim. It may be necessary to use several the photograph. wide hard balsa can be cut to form a frame at the nose.THE BASICS OF AEROMODELLING a little thicker than the bamboo used for the wing dowels. lightly and then give a coat of thinned dope taking precautions against warps (see Chapter 5). using strips of coloured tissue doped on. Leave a small part of the underside unsheeted under the dowel so that the rubber motor can easily be engaged. important for is flying characteristics. should not six panels. Cut out the shape and cement and pin in place. Leave this to dry. sighting to ensure that the tailplane ruler and is exactly parallel with the that the fin is exactly at right angles to the tailplane. of course. Remember little The fuselage and benefit from a thin coat of pieces as the available sheet balsa dv^indles. perhaps a bit of a solid garden cane or a Vain. using water-shrink outside the lines and sand the edges dov^n to a flush fit dowel for the rubber should be made by cementing acetate patches inside and drilling through for the size dowel available. Repeat for the remainder of the top and bottom. then remove the pins. non-shrink clear dope. Cover the wing. or c small amount of car trim tape or a decal (transfer). . banana lightweight tissue. This good ing. bottom and top. Provision for the rear oil or sand- sanded with very fine glasspaper to a smooth finish when dry. as is shown be included if draw round the area in contact. For a strip harder wear- of Vain. but do not add too much weight. to cut a this the glider-only version with a fixed noseblock lightly in not essential and. but tail surfaces will is built. (10m) of line at first cloth tow at only just above the model's speed .THUMBELINA top. The finished tip shows slight rounding and gussets in to the place. following the procedure in Chapter 6. (200-230mm) can be used for powered version of this model. (50mm) length from a round pencil and check that the notches in the blades are a good fit on it. Allow to dry. A piece of aluminium foil acetate sheet can be cemented on the or t. bottom of the tip rib) and the remaining spars added. (75mm) diameter as shown. on the t. the leading and trailing edges cracked and cemented with the (measured raised tip I V2 in.e. Wing bands are just visible. Try a gentle hand glide. winding round with soft string or using rubber bands. plastic propeller of 8 or 9in. these are crossed over wing. until the model balances on the centre spar. of one wing near the tip and bent as needed to produce o very wide. but let it fly out of his hand. Note notch for rubber band. Adjust the trim as necessary. bottom. or nuts or turns of solder to the bolt or screw if used. A finger underneath at the dihedral break each side will give a reasonable idea of balance. (230 X 25 X 15mm) or that shown on the model used. First cut four '/)6in. noseblock for the (convertible) glider version. diameter the rubber- or one can be carved from a balsa block 9 x 1 x Vein. the wing built with the centre section spars Opposite. then and try to flying enjoy longer A flights. flat in place. Your assistant should not try to launch the model. gentle turn. then sand to approximately the section shown. Use only about 30ft. Tie a small of the rudder. blades. Right. in if you used Add weight the ballast box. Cut a 2in. The glider version of the prototype weighed a shade under 1 %oz (neorly 50gm) in flying condition.e. cement together in pairs and position while the cement is wet on a jar or tin 3in. more heavier balsa than the original. or wire ring to the end and a tissue or light pennant about a foot from the ring. Opposite. a spool of thread will be adequate. For towing. Drill a fine 55 .in only a light breeze you could probably stand still and the model will still climb. For the glider around y20z (14gm) of ballast will be needed. as drawn. cement and push back in. if necessary. the tube it and drill 1 a 8swg V\6\r\. A broken needle can be used as a drill. working it round the hook by lightly wetting Slide a tinplate bearing if necessary (rubber tube is better than can be used).) using an old pair of scissors and punch a hole in each with a sharp panel pin or fine nail. piece of insulation tube from an old piece of electrical flex and slide onto the shaft. enlarging needle file. remove. shaft hook. Cut two tiny shapes. The propeller blades rubber-banded to_ a suitable diameter bottle. use a piece of alunninium or brass tube hole. sheet (or cut from y4in. and not pointing up or down or hole accurately through the centre and another Vsin. sheet from a balsa pack) has a plug on the back made from two laminations tinplate (from a of '/i6in. If these cannot be found use tiny flat washers with a glass bead between. Bend the triangular tabs to 90 degrees. it is better to punch the holes first and then cut out. which exactly fits the nose aperture may be held in by a rubber band as previously described. that the corner of the hook is in line with the straight part of the shaft. The noseblock. on each side and press the tabs into the balsa. Push a pin through on the shaft line. Alternatively. or in desperation just a glass bead! Slide on the prop (the plastic but either Set the blades hub up on the and the jig (see sketch) ensuring that the vertical. (9nnnn) from it. AEROMODELLING . Slip the shaft through the bearings and slide on a pair of cup washers. either by snapping off the eye and using it in a handdrill or by pushing the point into a piece of wood and heating the other end to burn a way hole through.THE BASICS OF. from a piece of thin can or biscuit tin etc. Cut a ^in. which can be laminated from '/i6in. checking that it is straight through and. then follow the hole through with a piece of the 18g wire. and the an expert would do it. as necessary with a round then roughening the outside of and cementing Bend the propeller it in the hole. 56 wire is . ensuring to one side. long. as described earlier from five feet rubber (150 x 3mm) into four braided to end up about 12in. Insert in the model and on the centre spar as before. state categorically sketch). thin rubber band. in which case only a right-angle bend is needed on the shaft.THUMBELINA The glider version about to be towed up. (30mm) is now needed Launching the is the rubber motor. It is best to leave out the bamboo dowels and slip the wing in place with one large. holding wound motor to unhook and then hook the propeller assembly in place.) The loop allows easy winding and a small pawl through the second hole in the prop hub makes an efficient freewheel device (see the of Vain strands. right way round) and bend the little loop on the front end using round-nose pliers. (If a prop is used it is likely to have a moulded-in romp on the front of the hub. Launch level or slightly start downward. 57 . powered All that made up It is not possible to where the model will rubber version should from this position. Note pennant on towllne tissue and slight nose-up angle of model. can then be marked and the dowels fitted as appropriate. You then have to wind plastic by hooking the rubber to the winder. allowing it to be slid fore and balance it aft to find the position This required for balance. the 58 . picture 3. Finally carve the front. up To carve a propeller start with a medium to hard balsa black 9 x IV2 x 1 in.THE BASICS OF . then draw on the sides as picture 2. then follow first picture. is Make tailplane and structure of clear from this sure that the fin are square to the fuselage and line properly with the wing. Saw out and mark the ends into thirds. AEROMODELLING The simple Thumbelina view. sanding the heavy blade or side until it will remain still in any position. Saw the end tapers. then carve the back of the blades. cut the hub and blades to shape and balance the prop by trying it on a wire through the shaft hole. Mark off into quarters. strip (or up the glide is to '/sin. or four of '/i6in.) under the wing too steep or under the t. For more power use either six strands of Vain.e. 59 . if if the glide tends to the rubber be Try a few turns on and add down and/or stally.THUMBELINA balance because of variables such as the weight of the sheet balsa used and the possible differences in weight between a plastic prop or a wood one. initially The motor when broken in should take at least 600 turns. I. Small adjustments may be made by packing a '/i6in.e. and don't forget your name and address on the model! side thrust with thin packing as needed. helicopters with the difference the ground. Radio permits a model to do anything of which a full-size aeroplane is capable. radio-controlled models stage allowed the model to get too far hardly come under away and cannot decide whether is flying away or towards them. It should be said that the person who is prepared to spend a lot of money on a finished model or an almost-ready-to-fly (ARTF) kit think that they are the only become a committed aeromodeller than someone and associated radio who wants to build is and less likely to order to learn. which is the electro-mechanical device which actually operates the function and simply plugs into the receiver which switches it on and off in the direction selected by the control on the transmitter. elevator very is may be short while. or even sometimes if is the right way up! Most clubs have one or two instructors who can teach new members to fly and no-one should the category of basic aeromodelling. 2. who can add further channels at a moderate cost. makes sense fliers who have been doing it since days and still derive enormous pleasure from it. so if initially but buy a four-function transmitter and receiver. 7 or even 8 in number. you need only buy one expensive. In the case of an expert. For example.to make the model turn to your left as it goes away from you. but since they attract the most publicity. At current prices. 5. so it to buy a four-function set at the outset. any delay is infinitesimal but a novice can experience a lot of difficulty. Equally. Almost all beginners have at some 60 initially identified by its which single. Orientation is a problem . Each function requires a servo. One early decision is whether to use dry or rechargeable nickel-cadmium batteries. You can add further servos as needed and some sets are extendable by the manufacturer. other pursuit which takes their fancy for a the to take opportunities. using only such channels as are required to start with. left rudder is applied. some outline should be included. The cost of nicads plus a charger does add quite a bit to the initial expense but will give probably three seasons of flying without except for the further outlay amount of electricity negligible needed for charging need to be replaced whereas dry cells will after every two hours or so of use. of course. 3. (3f) (If) or rudder/throttle but you will (2f) progress to and then to ailerons (4f). there are radio advantage of such of functions or channels. It is advisable to look ahead and buy an outfit which will allow you more scope than you at first need. there people who take up R/C in way possible but dinghy models a through-put of fly free-flight who is flying in the easiest next year will sailing or off-road racing or be some it it be too proud A radio system number a rudder-only trainer is fine. to make it turn to your left as it comes towards you right rudder is needed and some people have great difficulty getting used to this. the pilot has to wait until circumstances develop to a recognisable point before he can react. and indeed some people form of model aircraft. but there is still a lot of enthusiasm for aerobatics and demanding areas such as early and pylon racing. Many of these have turned to accurate scale modelling. Servos you are going to are fairly fly rudder-only. 6.CHAPTER EIGHT Radio control Strictly speaking. that the pilot is on so instead of instantaneous recognition of and reaction to changing circumstances. nicads could prove cheaper after . 4. Incidentally. a one of which is servo. wires for battery input and switch and an aerial wire.0 from dry Modern cells. span for c four-stroke engin' and E. platform or box built taneously. The crystal is a quartz which resonates at a parfrequency that is matched by a crystal the transmitter. it and Always possible to start by using dry cells is change to nicads at a later stage. 5 1 Dolphin 'A in. a basic dry cell is 1 . These crystals control the slice of ticular in radio frequency on which the equipment operates and they can be changed to another pair to alter the frequency. the securing screws or bolts passing through rubber Photos above show. is simply a small box with sockets for servo plugs. 61 . left. it into the model using rubber bands. which is why a number of models can operate simul- Normal procedure is to wrap the receiver in foam rubber and hold against a bulkhead. read the supplier's instructions and follow them faithfully to get good results from both radio and nicads. right. However.2. Sapcote. receiver and two servos. cope The receiver radio is designed to with this difference. Right. airborne equipment for two functions — switch and charging socket.RADIO CONTROL less than twenty flying sessions. plus an additional socket for a crystal. so six of the latter give 7. and.5 volts but a nicad is 1 . in. needed for each control. attractive Sopwith 45 cu. nicad pack. four radio functions b. as a rule. The servos are mounted or on rails in cut-outs in a ply shelf across the fuselage.2 volts as against 9. the clevis ends of the wire in being cut off and bound to the balsa rod. also adequate movement to avoid servo stall. not for beginners! 62 . For longer pushrods. Designed built grommets to absorb engine vibration. h. Pushrods. There are three general forms of linkage from the servos to the controls — pushrods.THE BASICS OF . such designs are Clive Weller. are wires fitted with clevises at each end. a square hardish balsa strip or a balsa dowel is used.. Friction-free control and by Trevor Waters. This is 68 possible in. fast — including undercarriage 10 cc — powered aerobatic design by At well over 100 m. if short. again wrapped in rubber (not plastic) foam so that it will not domage radio components the event of a crash. p. one to engage the servo output disc or arm and the other to a horn on the control. the battery pack is usually stowed forward of the rest of the radio. using two -40 (6V7 cc) twostroke engines. Snakes consist of wires. As the heaviest item. A common application for a snake is throttle operation. movement is required and the move movement should be able to farther than the servo a little so that is no risk of stalling the servo motor. The clevises are threaded on to a screw thread on the wire so that the pushrod overall length can be adjusted. bowden cables or fine plastic tubes sliding inside an outer tube. Low friction is again important. The inner member has a clevis on either end and the outer tube has to be secured in place at intervals so that it cannot there be displaced by the movement of the inner part. AEROMODELLINC Almost anything with radio. A-10 Thunderbolt uses twin ducted fans instead of propellers. where a pushrod would need slots to accommodate the slight sideways movement inherent in its Five functions retracting are used 54 in this in. snakes and closed loops. thus allowing operation through gentle bends. the tube passing through drilled holes in engine bulkheads etc. An additional use of a trim one is if it fully to also put hard it can operate the trim nearer to the centre can be put hard over without it does not have the extra control movement given by the trim. or a converted free-flight model which has in- can help. There is therefore no danger of pushing an insufficiently stiff pushrod which action. by means of a double horn on the control connected to both sides of the servo arm by two lengths of light wire or strong thread. (45m). Left-hand may operate stick right-hand one rudder or ailerons. giving about 1 0% of total movement. glitch-free control should 63 . There are several books available (ask your local library) and you should read as much as possible before even deciding on your choice of model. preventing full control being applied. There are trims on the transmitter which are used to bias the controls. made with A pre-flight check can be the Tx aerial retracted. the sticks being sprung so that control surfaces return to neutral when the sticks are released. The range of R/C equipment is herent stability actually out of sight (at least 1 V? miles) pro- vided the batteries are charged and the right crystals are in place .one is marked Tx and one Rx . a switch. The exception to this is throttle. you can have rudder control and motor on/off using a single channel. a slow-flying model of the powered glider type is an advantage. This can be allowed to fly itself to a reasonable height before experimenting with the controls and may well recover to normal flight if the controls are allowed to neutralise if a mistake is made. Modern radio allows whatever degree of control application the flier wants.and the Tx and Rx aerials are extended. when full be evident at a minimum of at least 50 yd. Meter shows state of charge of nicod batteries. i. if is the stick to put is over to that side momentarily. If learning to 'fly radio' without an ex- perienced tutor. If the rudder stick on the transmitter is moved halfway left. could bow in the middle. where the stick remains in the position to which it is moved.RADIO CONTROL A two-function transmitter. and the Move the no need permanently off-centre. throttle or elevator.e. model not flying straight the rudder trim is is used to adjust to hold the stick it so that there side when. A closed loop operates with a pull whichever way the control is required to move. the model's rudder will move halfway left and so on. This is used to switch on electric model's motor on and off without requiring stick activating the switch since a separate channel. For example. A1 Aerofoil Also Camber towing of a glider to launch Canard 'aerofoil section'. produce deceleration. rees Bulkhead form a T or a short. often metal. set often naturally lightweight tropical Banana which relative to a datum Balsa at Centre-section wood top and/or bottom of a to in- crease aircraft drag and etc. less popular glider wing from fuselage. angle at which Angle of the attack aerofoil meets the air (not Angle of the incidence aerofoil (wing or tailplane an related to any structure). very lightweight tissue used elastic rope. exerting pilot's side. Aileron along the entire extendable panels to without external structural Capping thin strip of support. height by a powered air- craft. usually solid. usually of solid sheet balsa the air- hardwood. Airbrakes the curvature of a cross- Cantilever usually at the tip but occasionally (but section. of 'airfoil'. Collet a stub of thick-walled tube air equipped with a grubscrew through the wall. e. Aerotow often openwork structure spacing models. a form of fuselage having a greater-than-essential class. tissue for covering indoor flying at a point of stress or Compressed loading. an line.) an aerofoil. form of aircraft using a noseplane preceding the wing(as opposed to a rear tailplane). movement converting section. sited oft Clevis at Cabane and aerofoil. an lines applied into a Bungee the fore a pivoted component. a form of motor running on a supply of air pumped cotton-covered multistrand Condenser into a reservoir. on rib used for mounting wings to fuselage. 64 width of construction.Glossary A2 smaller. linkage of two position in for an aircraft. . angle is frame mounted on Chord Chuck glider oil Bellcrank common 90 deg- a movement a hand-launched glider a forked connector carry- Closed loop a ing a pin on one control Cockpit the a pull either way. a main fuselage crossmember. also used as an abbreviated form of not necessarily) including a transparent area. half span. force 90 degrees to the force. with holes at I middle portion of a wing structure most flat a form of cellulose lacquer. cross-section. competition glider class Cab in used internationally. a lifting surface. movable control surface on trailing edge of wing.g. 65 . it is Glowplug anhedral. con- Leading edge a component of a model. Geodetic safe working on a two-stroke Dihedral cycles per second of oscillation (of radio Fuselage a constant frequency controlling and drive 'windmill' freely. an etc. etc. usually Fin for of angle to a circular cross-section. ultra-light and used in fragile covering for indoor models. equipment etc.) surfaces with short omni- principle. seen from ahead. attachment of control lines to C/L model. etc. light Longeron to increase manoeuvrability. wood machined movable control surface horizontal tailplane on control surface combining Horn projection to which small a control rod or cable is attached to operate a moving surface. Elevon term slang more than a centre change ening Elevator structural but has electrodes connected by a fine coil of If it preparation used for taut- Dowel curved of intermittent malfunction. stringers. nitrate or butyrote cellulose Hardwood covering. is Glitch V angle of a wing inverted. the forward extremity of a ventionally at the rear of (I. a spark ignition petrol engine (or one running on CO2 or other inert gas). Dope construction descent. in model terms. strictly.e.) wing tion of tailless aircraft. with space within for crew. Delta a triangular shaped wing. motor etc. tail. a strip of V7 or timber from a deciduous any wood ling modelhard in characteristics. on Flaps brief wire which glows on it movements of both elevators and ailerons. Freewheel engage from Cup). if is polyhedral. but in and/or airproofing the aircraft with the rudder Folder or similar to a sparking plug 2 volts. Dethermaliser device usually tailless. Crystal ability of propeller to dis- Microfilm methyl alcohol. wing Former 1 tree. one of the main fore and guide aft for members of a basic fuselage structure. hinged to movable surfaces at the trailing edge to steepen glide and reduce stalling speed or (C/L) airscrew structural member providing it. Crutch o strong shallow frame forming a base for a fuselage built with formers and slice of Frequency quartz vibrating at Gas engine a radio signal. Jig a firm support for accurate construction and/or repeti- fixed vertical surface.GLOSSARY Coupe d'Hiver rubber-power com- small category originFrance (Winter petition ating in giving shape required. glow engine fuel. for produce Diesel the spoiling model's trim order to in but rapid directional compression-ignition engine members. the slight wave main structural member mounting wings. or the structural member Lead-out it. Methanol (propeller) with folding blade(s). member through wing or Spark of flying or structural fuel.e. (t. wing position spaced above rubber-powered scale flying model up to 1 3in. Also a turn mark in R/C tubing properties link and aft member giving shape to a wing or tail.e. usually. fore Sanding sealer cellulose-based on radio transmitter. control drag of. position. occasioned by lift control Stick(s) racing events.. in side vertical flight. in a the stresses skin with minimum all engine mounting(s) separate Nicad from main fuselage. Pylon mixture the distance rotation of the Pushrod component. taining member structural light giving shape to the fuselage. gliders to facilitate a glider having the scale Rib an devices to in the lateral axis. a pattern for marking or cutting round. Power in electric spark. a fuse- lage of round or oval cross- aircraft section. Thermal influencing the direction of filler tube launching. peller (airscrew). tail firing of fuel/air engine cylinder by means to Sin. mem- . Orientation still (usually reduced). lever(s) operating by pushing and pulling a moving surface via a horn.) edge the rear etc. the fuselage. rotation of the model about of Template with used bungee cord in elastic place for glider angle of wing I. Ornithopter wood Servo sometimes used. awareness filling etc. Sweepback the longitudinal axis. cell. Surgical plastic form of competition power model carrying the wing on top of a forward fin. name original for reproduction of an aircraft in a different size Scale internal structure. a fixed tube. AEROMODELLING Monocoque carrying etc. nickel-cadmium rechargeable 1. Trailing fluid air a rising current. Nacelle Nordic or clay) grain etc. edge of a wing or the structural ber forming it. electro-mechanical control Slabsider fuselage device switched by radio. top/bottom cross-member connecting two longerons.2v glider.THE BASICS OF. span. from movable warm con- powder (talc bubbles forming descends. for A2 class of relative Snake Parasol powered wings Petrol engine Span Spar model up Pitch ignition Spoilers moved forward one revolution by a proStall scale slope soarer. internal combustion engine employing spark ignition. lateral straight line. rubber-powered scale member distance between extreme tips of using petrol (gasoline) for Pistachio servo. Stringer vertical losing of airflow. 66 of breakaway but without engine(s). Streamliner in the model sense. balanced by sink as cooler air surface travel. span. Also the PSS wings or tailplane. Peanut Spacer from rod control enclosed aircraft using flapping for rectangular of cross-section. Rudder lift loss model about shape of a powered Roll increase and reduce height and landing. struts competition rubber model inci- dence towards the wingtip. the used internationally since 67 . Yaw model rotation of about the vertical axis. Also an adjustment on a 1928. drum winding on launch line com- prising the landing gear. radio transmitter. Wakefield Winch etc.GLOSSARY Trim balance of forces acting on a model which must be achieved for stable flight. usually hand powered. Wash-in the concavity of the underside of a Undercarriage wheels wing and Wash-out decrease of angle of incidence towards the wingtip. Undercamber increase of angle of for glider. . . Model categories and simple traditional construction are covered together A drawing for a chuck glider is included which together with easily scaled plans for a rubber powered model gives with trimming and flying. you all you need to know full-size for a successful launch. . the simple materials and requirements necessary to master the basics of aeromodelling.Aeromodelling This book discusses in an easy-to-understand way.