A transverse-rotor aircraft is an

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

with two large horizontal

rotor ROTOR was an elaborate air defence radar system built by the British Government in the early 1950s to counter possible attack by Soviet bombers. To get it operational as quickly as possible, it was initially made up primarily of WWII-era syst ...

assemblies mounted side by side. Single-rotor helicopters (unicopters) need an additional

tail rotor The tail rotor is a smaller rotor mounted vertically or near-vertically at the tail of a traditional single-rotor helicopter, where it rotates to generate a propeller-like horizontal thrust in the same direction as the main rotor's rotation. ...

or tail exhaust to neutralize the

reaction Reaction may refer to a process or to a response to an action, event, or exposure. Physics and chemistry *Chemical reaction *Nuclear reaction *Reaction (physics), as defined by Newton's third law * Chain reaction (disambiguation) Biology and ...

angular momentum Angular momentum (sometimes called moment of momentum or rotational momentum) is the rotational analog of Momentum, linear momentum. It is an important physical quantity because it is a Conservation law, conserved quantity – the total ang ...

produced by the main rotor. Transverse rotor helicopters, however, use counter-rotating rotors, with each cancelling out the other's torque. Counter-rotating rotor blades also won't collide with and destroy each other if they flex into the other rotor's pathway. In addition, transverse rotor configuration has the advantage of higher payload with shorter

blade A blade is the Sharpness (cutting), sharp, cutting portion of a tool, weapon, or machine, specifically designed to puncture, chop, slice, or scrape surfaces or materials. Blades are typically made from materials that are harder than those they a ...

s, since there are two sets working to provide

lift Lift or LIFT may refer to: Physical devices * Elevator, or lift, a device used for raising and lowering people or goods ** Paternoster lift, a type of lift using a continuous chain of cars which do not stop ** Patient lift, or Hoyer lift, mobile ...

. Also, all of the power from the engines can be used for lift, whereas a single-rotor helicopter must divert part of its engine power to generate tail

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

. Transverse rotor design with rotatable

nacelle A nacelle ( ) is a streamlined container for aircraft parts such as Aircraft engine, engines, fuel or equipment. When attached entirely outside the airframe, it is sometimes called a pod, in which case it is attached with a Hardpoint#Pylon, pylo ...

s are known as

tiltrotor A tiltrotor is an aircraft that generates lift (force), lift and thrust, propulsion by way of one or more powered Helicopter rotor, rotors (sometimes called ''proprotors'') mounted on rotating shaft (mechanical engineering), shafts or nacelles ...

s while designs where the whole wing rotates are known as

tiltwing A tiltwing aircraft features a wing that is horizontal for conventional forward flight and rotates up for vertical takeoff and landing. It is similar to the tiltrotor design where only the propeller and engine rotate. Tiltwing aircraft are typic ...

List of transverse rotor aircraft

Transverse-mounted helicopters

Bratukhin B-11 The Bratukhin B-11 was a prototype Soviet twin-rotor transport helicopter and the last design of the Bratukhin Bratukhin, or OKB-3, was a Soviet aircraft design bureau created in 1940 from within TsAGI to develop helicopters. Headed by Ivan Pavl ...

(1948) * Bratukhin G-3 (1946) * Cierva W.5 (1938) * Cierva W.11 Air Horse (1948) - a three rotor helicopter * Firth Helicopter (1952) * Focke-Achgelis Fa 223 Drache (1941) *

Focke-Wulf Fw 61 The Focke-Wulf Fw 61 was the first successful, practical, and fully controllable helicopter, first flown in 1936. It was also known as the Fa 61, as Focke began a new company— Focke-Achgelis—in 1937. Design and development Professor Henri ...

(1936) * Kamov Ka-22 (1959) * Kamov V-100 (1980s) - unbuilt project * Landgraf H-2 (1944) * McDonnell XHJH Whirlaway (1946) * Mil Mi-12 (1967) * Platt-LePage XR-1 (1941)

Transverse-mounted tiltrotors

AgustaWestland AW609 The Leonardo AW609, formerly the AgustaWestland AW609, and originally the Bell-Agusta BA609, is a twin-engined tiltrotor VTOL aircraft with an overall configuration similar to that of the Bell Boeing V-22 Osprey. It is capable of landing vertic ...

* Bell Eagle Eye *

Bell XV-3 The Bell XV-3 (Bell 200) is an American tiltrotor aircraft developed by Bell Helicopter for a joint research program between the United States Air Force and the United States Army in order to explore convertiplane technologies. The XV-3 featured ...

* Bell XV-15 *

Bell Boeing V-22 Osprey The Bell Boeing V-22 Osprey is an American multi-use, tiltrotor military transport and cargo aircraft with both vertical takeoff and landing (VTOL) and short takeoff and landing (STOL) capabilities. It is designed to combine the functionalit ...

* Bell V-280 Valor

Transverse-mounted tiltwings

* Canadair CL-84 Dynavert

References

Works cited