Helicopter rotor - Wikipedia, the free encyclopediahttp://en.wikipedia.org/wiki/Helicopter_rotor Helicopter rotor From Wikipedia, the free encyclopedia A helicopter main rotor or rotor system is the combination of a rotary wing and a control system that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight. Each main rotor is mounted on a vertical mast over the top of the helicopter, as opposed to a helicopter tail rotor, which connects through a combination of drive shaft(s) and gearboxes along the tail boom. A helicopter's rotor is generally made of two or more rotor blades. The blade pitch is typically controlled by a swashplate connected to the helicopter flight controls. Helicopters are one example of rotary-wing aircraft. Helicopter rotor The rotor head of a Sikorsky S-92 Contents 1 History and development 2 Design 2.1 Parts and functions 2.2 Swash plate 2.3 Fully articulated 2.3.1 Aircraft 2.4 Rigid 2.5 Semirigid 2.5.1 Flybar (stabilizer bar) 2.5.2 Aircraft 2.6 Combination 2.6.1 Aircraft 3 Rotor configurations 3.1 Single main rotor 3.1.1 Tail rotor 3.1.2 Ducted fan 3.1.3 NOTAR 3.1.4 Tip jets 3.2 Dual rotors (counterrotating) 3.2.1 Tandem 3.2.2 Coaxial 3.2.3 Intermeshing 3.2.4 Transverse 3.3 Quadcopter 4 Blade design 5 Limitations and hazards 5.1 Abrasion in sandy environments 6 References 7 External links 1 of 11 04-07-2013 12:53 Main rotor systems are classified according to how the main rotor blades are attached and move relative to the main rotor hub. The Russian polymath Mikhail Lomonosov developed a rotor based on the Chinese toy.[10] a low disc loading (thrust per disc area) greatly increases the aircraft's energy efficiency. the main rotor on a helicopter has a large diameter that lets it accelerate a large volume of air. Design The helicopter rotor is powered by the engine. As it is more efficient at low speeds to accelerate a large amount of air by a small degree than a small amount of air by a large degree. Cierva is credited with successful development of multi-bladed. to the rotating mast.Wikipedia. autogyro pioneer Juan de la Cierva researched and developed many of the fundamentals of the rotor.Helicopter rotor . image from the German Federal Archives In the 1930s. The mast is a cylindrical metal shaft that extends upward from—and is driven by—the transmission. German master engineer. describes the apocryphal use of a possible rotor in aircraft: "Some have made flying cars [feiche 飛車] with wood from the inner part of the jujube tree. semirigid.[1] Sir George Cayley. using ox-leather (straps) fastened to returning blades so as to set the machine in motion. This system was used in several Bell and Hiller helicopter models.org/wiki/Helicopter_rotor History and development See also: Bamboo-copter and Science and inventions of Leonardo da Vinci The use of a rotor for vertical flight has existed since 400 BC in the form of the bamboo-copter.[11][12] Parts and functions 2 of 11 04-07-2013 12:53 . created multiple vertical flight machines with rotors made of tin sheets.[1] The philosopher Ge Hong's book the Baopuzi (Master Who Embraces Simplicity). It is also used in many remote control model helicopters. would inspire the Wright brothers to pursue the dream of flight. This permits a lower downwash velocity for a given amount of thrust. The toy consists of a rotor attached to a stick.[5][6][7][8][9] Unlike the small diameter fans used in turbofan jet engines. The rotor blades are then attached to the hub. powered by rubber bands. or fully articulated. A decorated Japanese taketombo bamboo-copter. written around 317. the free encyclopedia http://en.[1] Alphonse Pénaud would later develop coaxial rotor model helicopter toys in 1870. fully articulated rotor systems.wikipedia. At the top of the mast is the attachment point for the rotor blades called the hub. given as a gift by their father. The spinning creates lift.[1][2] The bamboo-copter is spun by rolling a stick attached to a rotor."[3] Leonardo da Vinci designed a machine known as an "aerial screw" with a rotor based on a water screw. an ancient Chinese toy. This system. Arthur Young improved the stability of two-bladed rotor systems with the introduction of a stabilizer bar.[4] Before development of powered helicopters in the mid 20th century. One of these toys. 1927. and this reduces the fuel use and permits reasonable range. although some modern rotor systems use an engineered combination of these classifications. The French naturalist Christian de Launoy constructed his rotor out of turkey feathers. There are three basic classifications: rigid. inspired by the Chinese toy in his childhood. in its various modified forms. is the basis of most multibladed helicopter rotor systems. and the toy flies when released. Helicopter rotor of Engelbert Zaschka. The rotors are designed to operate in a narrow range of RPM. through the transmission. The swash plate can shift vertically and tilt. which defines the part of the rotor disc where the maximum thrust develops. The swash plate is two concentric disks or plates. transmitting cyclic and collective pitch to the blades (the top one rotates) Three non-rotating control rods transmit pitch information to the lower swashplate Main mast leading down to main gearbox The simple rotor of a Robinson R22 Robinson R44 rotor head Swash plate Main article: Swashplate (helicopter) Controls vary the pitch of the main rotor blades cyclically throughout rotation. carries the main shaft rotation down to the upper swashplate Rubber covers protect moving and stationary shafts Swashplates. The rotating plate is also connected to the individual blades through pitch links and pitch horns. Later models have switched from using traditional bearings to elastomeric bearings. or in response to a cyclic control input.[13] and not by Coriolis effect. or lowering the swash plate with the flight controls. the free encyclopedia http://en. the non-rotating plate controls the rotating plate. allows the blade to move back and forth. One plate rotates with the mast. called the flapping hinge. Pitch hinges. Collective pitch varies the magnitude of rotor thrust by increasing or decreasing thrust over the whole rotor disc at the same time. The purpose of the drag hinge and dampers is to compensate for the acceleration and deceleration caused by momentum conservation. allowing one blade to rise vertically while the other falls vertically. which in turn controls the individual blade pitch. feather. leaving the angle of attack of the blades as the sole means of adjusting thrust from the rotor.Wikipedia. Scissor link and counterweight. The basis of his design permitted successful helicopter development. These blade pitch variations are controlled by tilting. allowing the blades to twist about the axis extending from blade root to blade tip. The vast majority of helicopters maintain a constant rotor speed (RPM) during flight.Helicopter rotor . raising. dragging. connected by idle links. The non-rotating plate is connected to links that are manipulated by pilot controls —specifically. In a fully articulated rotor system. The blades are allowed to flap.[citation needed] A variation of the fully articulated system is the "soft-in-plane" rotor system. called the lead-lag or drag hinge. Teeter hinge. Through shifting and tilting. This motion occurs whenever translational relative wind is present. This movement is called flapping and is designed to compensate for dissymmetry of lift. allows the blade to move up and down. The horizontal hinge. This movement is called lead-lag. and lead or lag independently of each other. the collective and cyclic controls. The vertical hinge. and there may be more than one hinge. while the other does not rotate. This type of rotor can be found on several aircraft produced by 3 of 11 04-07-2013 12:53 . each rotor blade is attached to the rotor hub through a series of hinges that let the blade move independently of the others. or hunting. Fully articulated Juan de la Cierva developed the fully articulating rotor for the autogyro. Dampers are usually used to prevent excess back and forth movement around the drag hinge.org/wiki/Helicopter_rotor The simple rotor of a Robinson R22 showing (from the top): The following are driven by the link rods from the rotating part of the swashplate.wikipedia. These rotor systems usually have three or more blades. The flapping hinge may be located at varying distances from the rotor hub. The pilot uses this to control the direction of the rotor thrust vector. However. The result is a rotor system that has less lag in control response. Loads from flapping and lead/lag forces are accommodated through rotor blades flexing. at each end. A rigid rotor system is mechanically simpler than a fully articulated rotor system. By flexing. and Dieter Schlüter in Germany. This yoke is attached to the mast and runs through the blade grips between the blades and the shear bearing inside the grip. the blades themselves compensate for the forces that previously required rugged hinges. Through mechanical linkages. or paddles. usually opposing blades.wikipedia. These keep the bar relatively stable in the plane of rotation and reduce crosswind thrust on rotors. This system is normally composed of two blades that meet just under a common flapping or teetering hinge at the rotor shaft.[16] The rigid rotor system also negates the danger of mast bumping inherent in teetering rotors. the free encyclopedia http://en. In a rigid rotor system. such as the OH-58D Kiowa Warrior. This makes it easier for the pilot to maintain control of the aircraft. This system is similar to the fully articulated type in that each blade has the ability to lead/lag and hunt independent of the other blades. Hiller's "Rotormatic" system also delivered cyclic control inputs to the main rotor as a sort of control rotor. Semirigid rotor system 4 of 11 04-07-2013 12:53 . rather than through hinges.S. Aircraft AgustaWestland AW109 Rigid The term "rigid rotor" usually refers to a hingeless rotor system[14][15] with blades flexibly attached to the hub. minimizes variations in the radius of each blade's center of mass from the axis of rotation as the rotor turns. which allows changes to the pitch angle of the blade. Feathering is accomplished by the feathering hinge at the blade root. the flight characteristics are very similar and maintenace time and cost are reduced. This underslinging of the blades below the teetering hinge. Stanley Hiller arrived at a similar method to improve stability by adding short stubby airfoils. Secondary flapping hinges may also be provided to provide sufficient flexibility to minimize bouncing.Wikipedia. Young in the U. which was tested and developed on a series of helicopters in the 1960s and 1970s. each blade flaps and drags about flexible sections of the root.[17] Example:MBB Bo 105 Semirigid The semirigid rotor can also be referred to as a teetering or seesaw rotor. While this is not fully articulated. the stable rotation of the bar mixes with the swashplate movement to damp internal (steering) as well as external (wind) forces on the rotor. among them Arthur M. Flybar (stabilizer bar) A number of engineers. which in turn reduces the stress on the blades from lead and lag forces caused by the Coriolis Effect. found that flight stability for helicopters could be achieved with a stabilizer bar or flybar. The flybar has a weight or paddle (or both for added stability on smaller helicopters) at either end. because the rotor has much less oscillation. The difference between a fully articulated system and soft-in-plane system is that the soft-in-plane system utilizes a composite yoke. This allows the blades to flap together in opposite motions like a seesaw. Irven Culver of Lockheed developed one of the first rigid rotors.org/wiki/Helicopter_rotor Bell Helicopter. combined with an adequate dihedral or coning angle on the blades. and the paddles provided the added stability by dampening the effects of external forces on the rotor.Helicopter rotor . This yoke does transfer some movement of one blade to another. Eurocopter's Fenestron (also called a fantail). This flybar-less design has the advantage of easy reconfiguration and fewer mechanical parts. the creation of torque as the engine turns the rotor creates a torque effect that causes the body of the helicopter to turn in the opposite direction of the rotor. The United States and Canada rotate counter-clockwise. similar in principle to that of the Bell stabilizer bar. They also absorb vibration. Some rotor hubs incorporate a flexible hub. In fly-by-wire helicopters or RC models. This is accomplished through a variable-pitch antitorque rotor or tail rotor.Helicopter rotor . Single main rotor With a single main rotor helicopter. These systems.Wikipedia. The three most common controls used today are the traditional tail rotor . require less maintenance. which allows for blade bending (flexing) without the need for bearings or hinges. Aircraft Bell 407 Bell 430 Eurocopter AS350 Rotor configurations Most helicopters have a single main rotor but require a separate rotor to overcome torque. Tail rotor Antitorque: Torque effect on a helicopter 5 of 11 04-07-2013 12:53 . and MD Helicopters' NOTAR. When viewed from above. To eliminate this effect. although designs do vary. while nearly all others rotate clockwise. the main rotors of helicopter designs from Germany. a microcontroller with gyroscope sensors and a Venturi sensor can replace the stabilizer.org/wiki/Helicopter_rotor The Lockheed rotor system used a control gyro. Elastomeric bearings may also be used in place of conventional roller bearings. Aircraft Bell 206/OH-58 Robinson R22 Combination Modern rotor systems may use the combined principles of the rotor systems mentioned above. United Kingdom. called "flexures". the free encyclopedia http://en. therefore. some sort of antitorque control must be used with a sufficient margin of power available to allow the helicopter to maintain its heading and provide yaw control. since the effects may manifest on opposite sides of each aircraft. This is the design that Igor Sikorsky settled on for his VS-300 helicopter. Flexures and elastomeric bearings require no lubrication and. and it has become the recognized convention for helicopter design. This can make it difficult when discussing aerodynamic effects on the main rotor between different designs.[18] are usually constructed from composite material. but designed for both hands-off stability and rapid control response of the hingeless rotor system.wikipedia. which means less fatigue and longer service life for the helicopter components. Elastomeric bearings are constructed from a rubber type material and provide limited movement that is perfectly suited for helicopter applications. therefore. and vertical stabilizers. NOTAR Main article: NOTAR NOTAR.[20] A variable pitch fan is enclosed in the aft fuselage section immediately forward of the tail boom and is driven by the main rotor transmission. Tail rotor of an SA 330 Puma Ducted fan Main article: Fenestron Fenestron and FANTAIL[19] are trademarks for a ducted fan mounted at the end of the tail boom of the helicopter and used in place of a tail rotor. the free encyclopedia http://en. as the FANTAIL. Ducted fans have between eight and eighteen blades arranged with irregular spacing so that the noise is distributed over different frequencies. thereby changing the direction the craft is pointed.Wikipedia. causing the downwash from the main rotor to hug the tailboom. the United States Army's RAH-66 Comanche. The pitch of the tail rotor blades is adjustable by the pilot via the anti-torque pedals. Hughes flew an OH-6A fitted with NOTAR for the first time.Helicopter rotor . Tail rotors are simpler than main rotors since they require only collective changes in pitch to vary thrust. The housing is integral with the aircraft skin and allows a high rotational speed. Diagram showing the movement of air through the NOTAR system Development of the NOTAR system dates back to 1975 when engineers at Hughes Helicopters began concept development work. Fenestron on an EC 120B The Fenestron was used for the first time at the end of the 1960s on the second experimental model of Sud Aviation's SA 340 and produced on the later model Aérospatiale SA 341 Gazelle.org/wiki/Helicopter_rotor Main article: Tail rotor The tail rotor is a smaller rotor mounted so that it rotates vertically or near-vertically at the end of the tail of a traditional single-rotor helicopter. Besides Eurocopter and its predecessors. Although the concept took some time to refine.[20] In December 1981.[21] A more heavily modified prototype demonstrator first flew in March 1986 and successfully 6 of 11 04-07-2013 12:53 . The tail rotor's position and distance from the center of gravity allow it to develop thrust in a direction opposite of the main rotor's rotation to counter the torque effect created by the main rotor. This is augmented by a direct jet thruster which also provides directional yaw control. is a helicopter anti-torque system that eliminates the use of the tail rotor on a helicopter. This fan forces low pressure air through two slots on the right side of the tailboom. the NOTAR system is simple in theory and provides antitorque the same way a wing develops lift by using the Coandă effect.wikipedia. producing lift and thus a measure of antitorque proportional to the amount of airflow from the rotorwash. an acronym for NO TAil Rotor . a ducted fan tail rotor was also used on the canceled military helicopter project. a ducted fan can have a smaller size than a conventional tail rotor. which also provide directional control by allowing the pilot to rotate the helicopter around its vertical axis. Wikipedia.74 was under-powered and could not fly. The Percival P. prototypes that have been built are less fuel efficient than conventional helicopters. Coaxial rotors are two rotors mounted one above the other on the same axis. raising the tail. This lets the aircraft apply the power that would have driven a tail rotor to the main rotors. pulse-jets. Primarily. simultaneously dipping the nose. Yaw control develops Boeing CH-47 Chinook through opposing cyclic pitch in each rotor. which was originally envisioned to take off using a rocket-tipped rotor. Other aircraft used auxiliary thrust for translational flight so that the tip jets could be shut down while the rotor autorotated. The experimental Fairey Jet Gyrodyne. To pitch upward while decelerating (or moving rearward). To pivot left. the front rotor tilts right and the rear rotor tilts left. three common configurations use the counterrotating effect on rotorcraft. Tip jets Main article: Tip jet The main rotor may be driven by tip jets. validating the system for future application in helicopter design. The air may or may not be mixed with fuel and burnt in ram-jets. Except for tip jets driven by unburnt compressed air. The Hiller YH-32 Hornet had good lifting capability but performed poorly otherwise. Intermeshing rotors are two rotors mounted close to each other at a sufficient angle to let the rotors intermesh over the top of the aircraft. the free encyclopedia http://en. 48-seat Fairey Rotodyne passenger prototypes and McDonnell XV-1 compound gyroplanes flew well using this method. This antitorque design also improves safety by eliminating the possibility of personnel walking into the tail rotor. Tandem rotors are two rotors—one mounted behind the other. Tandem rotors achieve pitch attitude changes to accelerate and decelerate the helicopter through a process called differential collective pitch. very high noise levels is the single most important reason why tip jet powered rotors have not gained wide acceptance. Tandem Main article: Tandem rotors Tandem rotors are two horizontal main rotor assemblies mounted one behind the other. where a pair of rotors are mounted at each end of a wing-type structure or outrigger. Dual rotors (counterrotating) Counterrotating rotors are rotorcraft configurations with a pair or more of large horizontal rotors that turn in opposite directions to counteract the torque effect on the aircraft without relying on an antitorque tail rotor. The French Sud-Ouest Djinn used unburnt compressed air to drive the rotor. research into noise suppression is ongoing and may help make this system viable. and the front rotor decreases collective pitch. To pitch forward and accelerate. and it is simpler to handle changes in 7 of 11 04-07-2013 12:53 . Such a system may be powered by high pressure air provided by a compressor. All rotor power contributes to lift.[22] There are currently three production helicopters that incorporate the NOTAR design. the front rotor increases collective pitch to raise the nose and the rear rotor decreases collective pitch to lower the tail. the rear rotor increases collective pitch. which minimized noise and helped it become the only tip jet driven rotor helicopter to enter production. increasing lifting capacity.org/wiki/Helicopter_rotor completed an advanced flight-test program. There are several examples of tip jet powered rotorcraft.Helicopter rotor . To pivot right.wikipedia. Another configuration—found on tiltrotors and some early helicopters—is called transverse rotors. or rockets. Perhaps the most unusual design of this type was the Rotary Rocket Roton ATV. However. the front rotor tilts left and the rear rotor tilts right. Though this method is simple and eliminates torque reaction. all produced by MD Helicopters. Wikipedia. as well as the world's largest helicopter ever built. During the Cold War. other design considerations plague coaxial rotors. It is also the configuration found on tiltrotors such as the Bell-Boeing V-22 Osprey and the AgustaWestland AW609. it requires the expense of two large rotors rather than the more common one large main rotor and a much smaller tail rotor. Intermeshing rotors have high stability and powerful lifting capability. the transverse rotor also uses differential collective pitch.Helicopter rotor .wikipedia. the lift provided by the advancing halves of each rotor compensates for the retreating half of the other. Coaxial Main article: Coaxial rotors Coaxial rotors are a pair of rotors mounted one above the other on the same shaft and turning in opposite directions. the Mil Mi-12. However. with coaxial rotors rotor systems. the free encyclopedia http://en. the Kaman K-MAX. But like the intermeshing rotors. HH-43 Huskie Mi-12 Quadcopter Main article: Quadcopter 8 of 11 04-07-2013 12:53 . is a dedicated sky crane design. The Boeing CH-47 Chinook is the most common tandem rotor helicopter. and control linkages for pitch changes to the upper rotor system must pass through the lower rotor system. This configuration is sometimes referred to as a synchropter. because the rotors must rotate in opposite directions. However. in forward flight. an American company. There is an increased mechanical complexity of the Kamov Ka-50 of the Russian Air rotor system because it requires linkages and swashplates for two Force. the transverse rotors use the concept for changes in the roll attitude of the rotorcraft. the Flettner Fl 282 Kolibri. The arrangement was successfully used in Nazi Germany for a small anti-submarine warfare helicopter. This configuration is found on two of the first viable helicopters. the mast is more complex.org/wiki/Helicopter_rotor the center of gravity fore-aft. Kaman Aircraft. The latest Kaman model. Also. Transverse Transverse rotors are mounted on the end of wings or outriggers perpendicular to the body of the aircraft. Similar to tandem rotors and intermeshing rotors. eliminating one of the key effects of dissymmetry of lift: retreating blade stall. the Focke-Wulf Fw 61 and the Focke-Achgelis Fa 223. produced the HH-43 Huskie for USAF firefighting and rescue missions. The advantage of the coaxial rotor is that. Intermeshing Main article: Intermeshing rotors Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions with each rotor mast mounted on the helicopter with a slight angle to the other so that the blades intermesh without colliding. but less hard than sand. Rotor blades are made out of various materials. Joseph Etchells. The main attraction of quadcopters is their mechanical simplicity. Gordon. 7-9. often titanium or nickel. ISBN 978-0-521-85860-1. An example of such tips are the tips of the BERP rotor. pp. but research into active blade control through trailing edge flaps is underway.wikipedia. and steel or titanium. Cambridge aerospace series. narrow airfoils with a high aspect ratio. Web extract (http://terpconnect. Robinson and others—must not be subjected to a low-g condition because such rotor systems do not control the fuselage attitude. 18. At night. with abrasion shields along the leading edge. respectively. sand hitting the moving rotor blades erodes their surface. Rotors to the left and right are in a transverse configuration while those in the front and to the rear are in a tandem configuration. ^ Taking Flight: Inventing the Aerial Age. Principles of Helicopter Aerodynamics. This can result in the fuselage assuming an attitude controlled by momentum and tail rotor thrust that causes the tail boom to intersect the main rotor tip-path plane or result in the blade roots contacting the main rotor drive shaft. which are very hard. sand hitting the metal abrasion strip causes a visible corona or halo around the rotor blades. sand striking the rotor blade can cause erosion. Benjamin Kopp and Cpl. a shape that minimizes drag from tip vortices (see the wings of a glider for comparison).Wikipedia.[24] Tips of some helicopter blades can be specially designed to reduce turbulence and noise and to provide more efficient flying.html) 2. recently fallen American and British soldiers.edu/~leishman/Aero/history. They generally contain a degree of washout that reduces the lift generated at the tips.[26] Abrasion strips on helicopter rotor blades are made of metal.umd. where the airflow is fastest and vortex generation would be a significant problem. from Antiquity Through the First World War 9 of 11 04-07-2013 12:53 . the free encyclopedia http://en.[29] References 1.Helicopter rotor . 2006. war correspondent Michael Yon referred to this corona effect as the "Kopp-Etchells effect" to honor Cpl. Cambridge: Cambridge University Press. J. since a quadcopter using electric motors and fixed-pitch rotors has only four moving parts.[25] Abrasion in sandy environments See also: Brownout (aviation) — Sensory illusions When operating in sandy environments. rear-left.org/wiki/Helicopter_rotor A quadcopter has four rotors in an "X" configuration designated as front-left. front-right. The effect is caused by the pyrophoric oxidation of eroded particles. ^ a b c d Leishman. This can damage the rotors and presents serious and costly maintenance problems. When a helicopter flies low to the ground in desert environments.[27][28] In 2009.[23] de Bothezat helicopter. including aluminium. and rear-right. causing the blades to separate from the hub (mast bumping). 1923 photo Blade design The blades of a helicopter are long. Limitations and hazards Helicopters with teetering rotors—for example the two-blade system on the Bell. composite structure. Rotorcraft blades are traditionally passive. Army Aviation and Missile Command (February 2004).kothmann.com/Papers /AIAAJournalAircraftPart2.edu/research /aero/aircraft/lockheed_cl475.faa. 24. Retrieved: 28 September 2010. ^ John M.gov/library/manuals/aircraft/media/faa-h-8083-21. Hexacopter. Seddon.000 Flight Hours" (http://www. Revised on 15 August 2002. ^ Alpman. Accessed at archive. Presented May 1.htm). ^ Model 286 (http://www.dk /books?id=X_X3nOODGLgC&printsec=frontcover&hl=da) p216. John Wiley and Sons.org/5NFat7fwZ). pp. 7. Accessed: 2 January 2010 ^ "Helicopters. ^ Joseph Needham (1965). Accessed: 25 February 2012. 21.nasm.WarbirdTech Volume 27. New actuators for aerospace (http://www.com/studyguides/index. Accessed: 2 January 2010 9.html).org/5Mvnymw0Y). C. American Helicopter Society. 2011. N.com." (http://www.pdf) page 44 Pacific Wings. 23.S. Octocopter .aeroengineer. 22.si. ^ "The Boeing Logbook: 1983-1987" (http://www. 1979.rotaryforum. November–December 2004. Science and civilisation in China: Physics and physical technology. 2010-02-19. 11–10. Delta D2 (http://www. Lockheed CL-475" (http://web.org/automaton/robotics /robotics-software/quadcopter-hexacopter-octocopter-uavs). Helicopter theory (http://books.edu/aircraft /lockheed_cl475. 4. Part 2. Retrieved: 28 September 2010.rdecom.. 2000. "Blades and Lift" (http://www. ^ Croucher. ISBN 1-58007-027-2. "Understanding Ducted-Rotor Antitorque and Directional Control: Characteristics Part II: Unsteady Simulations.wikipedia. p. FAA-8083-21.doc) page 3. ^ Johnson. Quote: [Rotor speed] "is constant in a helicopter".noliac.army.php?folder=Documents /UH-60BlackhawkSpecific&download=Uh60limits.google. Dennis R.google. JHU Press.php?t=961&page=2& highlight=Coriolis).pdf) Journal of Aircraft Vol. U. 14. Courier Dover Publications.mil /dticasd/sbir/sbir032/n184.webcitation.nasm.doc) US Army Aviation . Helis.C.ieee. 151.webcitation. 26.pdf). ISBN 978-0-9780269-0-5. Smithsonian National Air & Space Museum.Wikipedia. "These boots are made for flying: Rotor blades get new protective shields" (http://www. page 583-587. DTIC. pp. Lockheed AH-56A Cheyenne . 15. ^ Wieslaw Zenon Stepniewski.S. 8. Phil.5.dtic.usarmyaviation.com/history. 11. Retrieved: 10 March 2007.pdf) Noliac. 6.com/books?id=IYnl_XPggZYC&pg=PA353).Helicopter rotor . Government Printing Office. 18. Army Research. the free encyclopedia http://en. Development and Engineering Command 10 of 11 04-07-2013 12:53 . Taylor.5 MB. Quote: The rotor is best served by rotating at a constant rotor speed 10. Inventing Flight: The Wright Brothers & Their Predecessors (http://books. Courier Dover Publications. Boeing. ^ Mangeot et al. 35. ^ Johnson. ^ Landis. IEEE Spectrum.: U.com/Files/Billeder/05%20News /Diamond_actuator_for_aerospace. 25. Public Affairs Office. Anderson (2004). Pam. Professional helicopter pilot studies (http://books.com/forum/showthread. ^ a b Frawley 2003.mil/rdemagazine/200402 /itf_amrdec_boots. 6. Lyle N.com.com/pdf/Pacific_wings_P42-49_Delta_v4__bill_whitney. Retrieved: 25 February 2007. R. Retrieved: 16 February 2011. 20.dk /books?id=PawbFeAAllIC&printsec=frontcover&hl=da) p3.net/history/lockheed/lockheed12. ISBN 1-119-99410-1. ISBN 978-0-8018-6875-7.htm).org/wiki/Helicopter_rotor 3. Rotary-wing aerodynamics (http://books. Accessed: 25 February 2012. 5. p.S. RDECOM Magazine. ^ The UH-60 permits 95–101% rotor RPM UH-60 limits (http://www.org/5MvjUcNbi). UAVs" (http://spectrum. ISBN 978-0-19-516035-2. 1997. ^ "NOTAR Fleet Marks 500. 2000. 5. Wayne. Retrieved: 25 February 2007. Accessed: 25 February 2012. original link (http://www. Keys.google. ISBN 0-486-68230-7 12.org/web/20080101194953/http://www. ISBN 0-486-64647-5 13. U. Oxford University Press. mechanical engineering Volume 4. Accessed: 25 February 2012. "Quadcopter. 41.michaeljohnsonmp.archive. Simon Newman. ^ Connor. ^ Rotorcraft Flying Handbook (http://www. ^ FAA Flight Standards Service 2001 19.google.webcitation.MIL Word document. Basic Helicopter Aerodynamics (http://books.si. Federal Aviation Administration. ^ Jim Bowne. 22–23. ^ Markus Waibel. 8 May 2003.S. p. Specialty Press. No.dk/books?id=SgZheyNeXJIC&hl=da& source=gbs_navlinks_s) pp3+32. 1980. ^ Paul Bevilaqua : The shaft driven Lift Fan propulsion system for the Joint Strike Fighter (http://www. ^ Cox. ^ Rotary Wing Forum [1] (http://www. Emre and Long.helicoptervietnam.google. ^ John D. Washington D.org on 3 September 2007. (http://books. ISBN 1-56027-404-2." (http://www. U.html) 16.com/books?id=AovdKRWSqJAC& printsec=frontcover&dq=%22Professional+Helicopter+Pilot+Studies%22&hl=da& ei=LYZ4TdmcDMjRsgbj56TyBw&sa=X&oi=book_result&ct=result&resnum=1& ved=0CD8Q6AEwAA#v=onepage&q&f=true) page 2-11.google. Tony and Jenkins..com/books?id=YRqV_PayIKIC&pg=PA22). 17.htm) Helicopter Vietnam. "A secondary concern with the erosion of metal abrasion strips pertains to the visible signature that occurs .Blade Element Momentum Theory (http://www. 3.. you agree to the Terms of Use and Privacy Policy." 28. ^ "The Kopp-Etchells Effect" (http://www. by Arthur Young "The Kopp-Etchells Effect" (http://www.michaelyon-online.org/w/index. Hong.de/AviationImages /Rotorhead.Wikipedia. Texas. a non-profit organization..htm). Retrieved 2009-09-02.php?title=Helicopter_rotor&oldid=561875015" Categories: Helicopter components Helicopter aerodynamics Chinese inventions Leonardo da Vinci projects This page was last modified on 27 June 2013 at 20:51. US Patent 2.. Wikipedia® is a registered trademark of the Wikimedia Foundation." 27. Inc.com/the-kopp-etchells-effect. Retrieved 2009-09-04. "An equally important problem with Ti protection is that a visible corona or halo is generated around the rotor blades at night from the sand impacting the Ti leading edge and causing Ti to spark and oxidize. the free encyclopedia http://en.navy. United States Department of the Navy. for flybar invention. Retrieved 2009-09-02. p. war correspondent Retrieved from "http://en. May 27 – 29.aerodyndesign.b-domke. Office of Naval Research. Rosenzweig (2009-05-27).368. Grapevine.html) "Helicopter Aircraft" (http://www. Dispatch by Michael Yon.698. Chin-Jye (Mike) Yu.htm). External links Rotor Analysis .michaelyon-online.pdf) (pdf).vtol. ^ Office of Naval Research Broad Agency Announcement(BAA): Advanced Helicopter Rotor Blade Erosion Protection (http://www.Helicopter rotor .htm) Helicopter Rotorhead Close-up Image Gallery (http://www. American Helicopter Society.google.com/the-kopp-etchells-effect.pdf) (pdf). 11 of 11 04-07-2013 12:53 .onr.org/wiki/Helicopter_rotor (Provisional). ^ Warren (Andy) Thomas." 29. Text is available under the Creative Commons Attribution-ShareAlike License.com/patents?id=PYReAAAAEBAJ&pg=PA1& source=gbs_selected_pages&cad=2#v=onepage&q=&f=false)..mil/02/baa/docs/BAA%2008-011_ONRBAA%2008-011. "The 'corona effect' is characterized by distinctive glowing rings along metal or fiberglass rotor blades operating in desert conditions. Shek C." (http://www. 2009.wikipedia. causing a corona effect in sandy environments. Edwin L. additional terms may apply. By using this site.org/f65_bestPapers/productSupport. "Enhanced Erosion Protection for Rotor Blades: Paper presented at the American Helicopter Society 65th Annual Forum.wikipedia.com/ANALYSIS /ANALYSIS. BAA 08-011. Retrieved 2009-09-02.
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