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Topic: Tandem rotor

	Helicopter - Wikipedia, the free encyclopedia
		Turning the rotor generates lift but it also applies a reverse torque to the vehicle, which would spin the helicopter fuselage in the opposite direction to the rotor if no counter-acting force was applied.
		In the flying-wagon or tandem rotor system (sometimes called "flying banana" for the peculiar shape of early U.S. examples), the two main rotors are located at the front and rear extremity of a long, boxy fuselage that resembles a railway wagon.
		The main drawback of a tandem rotor is limited agility in air and the need for a highly trained crew, as the large main rotors have long outreach beyond the fuselage and may easily hit nearby obstacles.
	en.wikipedia.org /wiki/Helicopter (4918 words)

	Helicopter - Search View - MSN Encarta
		A small tail rotor is mounted vertically at the rear of the helicopter and produces a side thrust, preventing the fuselage from rotating.
		The upper plate rotates with the shaft and the rotor blades and rests on the lower plate, which is controlled by the cyclic pitch stick.
		The rotor autorotates, or autogyrates, as the autogiro is pulled through the air by a separate propeller.
	encarta.msn.com /text_761554235__1/Helicopter.html (2857 words)

	merits
		This is particularly the case for the lower rotor on coaxials and the rear rotor on Tandems.
		Tandems also suffer larger rotor/airframe interference effects, including a download penalty compared to single rotor machines, because the fuselage of a tandem is directly located below the region of the rotor flow where the downwash is highest.
		On tandems and coaxials, the interference between rotors introduces significant 'coupling effects,' and is unavoidable in all three control axes - roll, yaw, and pitch.
	www.enae.umd.edu /AGRC/Aero/merits.html (1002 words)

	FM 1-514 Chptr 3 - Rotor System Operation
		Each rotor operates the same as the main rotor on the single-rotor helicopter, except for the direction of rotation of the aft rotor and the method of keeping directional control.
		The trunnion, which is splined to the tail rotor gearbox shaft, drives the blades and serves as a flapping stop for the tail rotor.
		Some rotor blades are numbered from the center of rotation (center of the mast), which is designated station zero, and outward to the blade tip.
	www.cavalrypilot.com /fm1-514/Ch3.htm (4156 words)

	Advanced Tandem Rotor Helicopter ( ATRH )
		Boeing was chosen to evaluate the Advanced Tandem Rotor Helicopter (ATRH), with a maximum speed of 165 knots.
		The Boeing Advanced Tandem Rotor Helicopter exploits the system maturity of the CH-47 Chinook, the extraordinary VTOL cargo-handling versatility and the unsurpassed maritime suitability of the tandem rotor platform, which uses two equally-sized rotors that spin in opposite directions for lift.
		The 360 has a high-speed articulating rotor system made of composite material that incorporates a new transonic airfoil and a planform design that can provide, according to Boeing, a 23 percent increase in cruise efficiency and permit cruise speeds in excess of 200 knots.
	www.globalsecurity.org /military/systems/aircraft/atrh.htm (700 words)

	Rotor Configurations
		The tail rotor compensates for the torque that is produced by the main rotor.
		The tandem rotor (or twin-rotor) configuration is used mainly with large helicopters.
		Like the tandem rotor, this configuration doesn't need a tail rotor because the torque is compensated for by the opposite rotation of the rotors.
	www.centennialofflight.gov /essay/Dictionary/heli_rotor_config/DI54.htm (346 words)

	Helicopter Aviation (Site not responding. Last check: 2007-10-12)
		Examples are the Boeing-Vertol tandem rotor helicopters which evolved from Frank Piaseki's designs, Charles Kaman's intermeshing rotor system, and the Russian co-axial helicopter (Hocum or Havoc I think it is, I'll have to look up the correct name I'm afraid).
		(tail rotor dissymetry of lift is discussed specifically in in the dissymetry of lift aerodynamics section).
		This is the Enstrom F28A tail rotor assembly.
	www.copters.com /mech/tail_rotors.html (1777 words)

	Directory of links to all things military. (Site not responding. Last check: 2007-10-12)
		Readily identified among current Navy and Marine Corps helicopters are the H-46 series Sea Knights, with their tandem rotor configuration setting them apart from the single rotor design of other Navy/Marine helos.
		Tandem rotors have been a feature of all production helos built by Boeing/Vertol, and its original predecessor company, Piasecki.
		The helicopter has the ability to land and taxi in the water in case of emergency, and is able to stay afloat for up to two hours in two-foot seas.
	www.worldnewsstand.net /2001/military/No49.htm (1146 words)

	Tanknet > NOTAR helicopters (Site not responding. Last check: 2007-10-12)
		Since the rotors are at the ends of the fuselage, there has to be a long driveshaft to carry the power to them.
		The overlapping rotor planforms means that the front rotor is working part of the time in the downwash of the rear rotor.
		Since the main rotor won't be producing downwash, the yaw moment will be coming primarily from the nozzle at the end of the boom rather than a combo of the nozzle and the Coanda Effect on the boom*.
	www.tank-net.org /forums/lofiversion/index.php/t2203.html (4137 words)

	Piasecki : Dogship and Flying Banana
		It is a twin-engine, tandem rotor, cargo helicopter.
		The two rotors were easier to manufacture and control than a single large rotor, and the long fuselage could be loaded with cargo or people, without much concern for even weight distribution.
		To ensure that the rotors did not hit each other, the rear end of the fuselage curved upwards so the rear rotor was higher than the forward rotor.
	www.centennialofflight.gov /essay/Rotary/Piasecki/HE4.htm (1365 words)

	Helicopter - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-12)
		It is as follows: turning the rotor generates lift but it also applies a reverse torque to the vehicle, which would spin the helicopter fuselage in the opposite direction to the rotor if no counter-acting force was applied.
		The NOTAR eliminates the tail rotor by conducting high-velocity air through the tail boom, utilizing the Coandă effect to produce forces to counter the torque.
		A helicopter should not be mistaken for an autogyro, which is a historical predecessor of the helicopter that gains lift from an unpowered rotor.
	www.knowledgehunter.info /wiki/Helicopter (4868 words)

	About Us
		Classic Rotors is a non-profit 501(c)3, all-volunteer organization dedicated to the preservation of rare and vintage rotorcraft.
		We are associated with the Hiller Aviation Museum, Experimental Aircraft Association, Naval Helicopter Association and the Canadian Museum of Flight.
		Classic Rotors memberships begin at $50 for ‘Whirlybirds’ (age 14 and under), and $100 for ‘Individuals’.
	www.rotors.org /aboutus.htm (634 words)

	The E Zone: Tech Model Products Dragonfly Pro R/C Electric Tandem Rotor Helicopter Kit.
		With both rotors balanced and tracking true, I did one more check of the swash alignment with both rotors fitted, and confirmed that both discs were running square to their masts and parallel to each other from both the side of the machine and the rear.
		As the front rotor was already running at 0 pitch at the bottom of collective, it was necessary to increase the pitch on the rear rotors.
		Tandem rotor helicopters (full-sized included) do have some flight characteristics that are quite different to traditional mono rotor helis.
	www.rcgroups.com /links/index.php?id=4964 (6283 words)

	THE HELICOPTER PAGE
		In a tandem rotor helicopter, you have no tail rotor, so there is no translating tendency to deal with, but you still have pedals for directional control at a hover.
		The only thing different in terminology for tandem rotor aircraft is the term "Thrust control", which is used to describe the collective pitch control lever.
		What the cyclic and pedals do is actually put inputs to the rotor systems to make them both tilt the same direction, as if there were two cyclics both putting in duplicate inputs to the two rotor systems.
	www.helicopterpage.com /html/tandem.html (1297 words)

	Military Factory - CH-47 Chinook (Site not responding. Last check: 2007-10-12)
		The venerable twin-engine, tandem rotor C-47 Chinook helicopter has undergone numerous upgrades since the first CH-47A model was delivered to the Army for use in Vietnam.
		The self-sealing fuel tanks are mounted in external fairings on the sides of the fuselage.
		The CH-47 Chinook is a twin-engine, tandem rotor, cargo helicopter.
	www.militaryfactory.com /aircraft/popup.asp?aircraft_id=56 (714 words)

	Helicopter Encyclopedia Articles @ BareHands.com (Bare Hands) (Site not responding. Last check: 2007-10-12)
		However these other configurations have a much higher cruise speed than a helicopter (270 km/h for a helicopter, 460 km/h for a tiltrotor, 900+ km/h for a vectored thrust airplane).
		The U.S. V-22 Osprey tilting rotorcraft is similar, although its nacelles can be rotated, and shares some of the inherent technical problems of a cross system.
		In the U.S. Navy it is commonly and properly referred to as the flight deck.
	www.barehands.com /encyclopedia/Helicopter (3816 words)

	Gear-To-Go Tandem Bicycles and Recumbents
		There are many reasons this brake has been mounted at the rear of your tandem as opposed to the front.
		Those reasons include the fact that due to the increased weight two riders exert on the rear wheel, it is virtually impossible to lock up the rear wheel under the most extreme braking- this makes it a wonderful location for such a smooth stopper.
		The spacing constraints of a road tandem's standard front fork means fitting a front disc will require either a special wider hub and fork (read nonstandard front wheel and fork) or a severely dished front wheel that is prone to collapse during a tandem's low-speed turns.
	www.gtgtandems.com /tech/chap1.html (1584 words)

	Coaxial Benefits
		Accordingly, the wetted area of the Coaxial on the same payload basis is much smaller than either the tail rotor or the tandem configurations, thus allowing for multi-coaxial vehicle storage in small hangar decks and therefore increasing shipboard multi-mission capabilities and utilization.
		The absence of a tail rotor from the Gyrodyne Coaxial permits all of the engine power to be used by the rotor system for lifting purposes.
		Therefore, in comparison with a tail rotor configuration, the useful load of the Gyrodyne Coaxial is higher.
	www.gyrodynehelicopters.com /coaxial_benefits.htm (1323 words)

	FM 1-514 Chptr 6 - Tandem-Rotor Power Train System
		The pump returns scavenged oil which collects in the forward part of the transmission when the aircraft is in a nose-down attitude.
		The purpose of drive shafting is to transmit torque from the engines to the transmissions and rotors.
		The purpose of the forward synchronizing drive shaft is to transmit torque from the engine-combining transmission.
	www.cavalrypilot.com /fm1-514/Ch6.htm (1600 words)

	Piasecki XHRP
		The situation was further complicated with these single-rotor designs because their center-of-gravity had to align closely with the axis of the rotor mast to ensure effective control.
		Most of Piasecki's peers did not share his enthusiasm for the tandem configuration, because they thought that in forward flight, the downwash from the forward rotor would destabilize that of the rear rotor, leading to a rapid loss of control.
		The pilot occupied the foremost of the two tandem seats for the crew.
	www.nasm.si.edu /research/aero/aircraft/piasecki_xhrp.htm (1313 words)

	THE U.S. ARMY'S CHINOOK REPLACEMENT (Site not responding. Last check: 2007-10-12)
		Boeing Vertol developed the tandem rotor from earlier designs built by legendary Frank Piasecki whose company built the earlier "flying banana" tandem design known as the CH-21 used in the early days of the Vietnam war.
		The closest example of wings helping rotors was the awesome U.S. Army AH-56 Cheyenne attack helicopter in the 1960s which was extremely fast but still had an anti-torque rotor in addition to a pusher propeller, so its 250 mph speed was only possible through mechanical complexity.
		By slowing rotor-tip speed to 100 RPM, the rotational aspect of the rotor profile HP is reduced to approximately 1/27th of the rotational profile HP at 300 RPM.
	www.combatreform.com /nextchinook.htm (11404 words)

	Tandem Rotor RC helicopter
		Since both rotors are intermeshing and synchronized, the main shaft autorotation hubs had to be replaced with solid hubs and fixed to the main shaft.
		The drive wire size increased to 1/8th inch music wire and the tail boom drive shaft nylon support inserts were all re-drilled to 1/8th inch.
		Servos will be installed in all the normal locations as on the single rotor version except of course for the front throttle servo.
	members.cox.net /arrio/tandem.htm (904 words)

	The RotorHead - CH-47 Chinook
		The CH-47 is a twin-engine, tandem rotor helicopter designed for transportation of cargo, troops, and weapons during day, night, visual, and instrument conditions.
		With a 60-foot rotor span, on each rotor system, the effective length of a CH-47 (with blades turning) is approximately 100 feet from the most forward point of the forward rotor to the most rearward point on the aft rotor.
		The first C model flew in late 1967 and became the mainstay of the Chinook fleet until the advent of the CH-47D.
	www.rotorhead.org /military/ch47.asp (2135 words)

	Tandem Rotor helicopter - RC Groups
		I decided to try a tandem rotor helicopter and the biggest initial challenge was how to make a simple rotor head and swash plate.
		But this tandem heli is a fantastic work of art and I hope you will bring it to the next fun fly.
		I just found an article in a helicopter stability and control textbook that describes how to tilt the rotor masts of a tandem rotor heli so that the 'pitchiness' with speed will be decreased.
	www.rcgroups.com /forums/showthread.php?t=86919 (1102 words)

	The Jesus Nut - Moriel Ministries
		The Jesus nut, also called the Jesus pin, is the hexagonal nut that holds the main rotor to the mast of some helicopters, such as the UH-1 Iroquois.
		The origin of the term is the idea that, if the Jesus pin were to fail in flight, the helicopter would detach from the rotors and the only thing left for the crew to do would be to pray to Jesus.
		Concerning tandem rotor helicopters it is the part that hold the whole thing together.
	www.moriel.org /articles/notice_board/the_jesus_nut.htm (425 words)

	Boeing: Boeing Announces Tandem Rotor Entry for Combat Search and Rescue Vehicle Acquisition
		The aircraft also has a special corrosion protection for the fuselage and rescue hoist.
		The aircraft is compliant with key performance parameters, and incorporates the advanced functionality to perform demanding CSAR missions.
		It is a leading provider of intelligence, surveillance and reconnaissance systems; the world's largest military aircraft manufacturer; the world's largest satellite manufacturer and a leading provider of space-based communications; the primary systems integrator for U.S. missile defense; NASA's largest contractor; and a global leader in sustainment solutions and launch services.
	www.boeing.com /news/releases/2005/q3/nr_050914s.html (738 words)

	gizmag Article: Advanced Tandem Rotor Helicopter (ATRH) contract for JHL program
		September 24, 2005 The U.S. Army has awarded a second contract to perform conceptual design and analysis of a vertical-takeoff-and-landing concept for the Joint Heavy Lift (JHL) program.
		Boeing proposed the ATRH in the Army's low-speed category, which is for vehicles that fly between 160 and 200 knots.
		The Boeing Advanced Tandem Rotor Helicopter exploits the system maturity, the extraordinary VTOL cargo-handling versatility and the unsurpassed maritime suitability of the tandem rotor platform, which uses two equally-sized rotors that spin in opposite directions for lift.
	gizmag.com /go/4646 (695 words)

	[No title]
		Popular Science 4 Turboprop hi-wing tilt wing transport circa 1966 had the potential to fly up to 400 MPH, much faster than the V-22, but it was hard to fly and keep working, a few cracked up.
		Tilt wings are harder to control than tilting rotors.
		Oil: Front Tandem - 17.5 qt.; Rear Tandem - 21.5 qt.
	www.arthurhu.com /index/militry.htm (12526 words)

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