Variable-incidence wing
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A variable-incidence wing has an adjustable angle of incidence relative to its
fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...
. This allows the wing to operate at a high
angle of attack In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is m ...
for take-off and landing while allowing the fuselage to remain close to horizontal. The pivot mechanism adds extra weight over a conventional wing and increases costs, however in some applications the benefits can outweigh the costs. Several examples have flown, with one, the
F-8 Crusader The Vought F-8 Crusader (originally F8U) is a single-engine, supersonic, carrier-based air superiority jet aircraft built by Vought for the United States Navy and United States Marine Corps (replacing the Vought F7U Cutlass), and for the Frenc ...
carrier-borne jet fighter, entering production.


History

Some early aeroplanes had wings which could be varied in incidence for control and trim, in place of conventional
elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...
control surfaces.
Wing warping Wing warping was an early system for lateral (roll) control of a fixed-wing aircraft. The technique, used and patented by the Wright brothers, consisted of a system of pulleys and cables to twist the trailing edges of the wings in opposite direc ...
varied the incidence of the outer wing and was used by several pioneers, including initially the Wright brothers. Early examples of rigid variable-incidence wings were not particularly successful. They include the Mulliner Knyplane in 1911, the Ratmanoff monoplane in 1913 and the Pasul
Schmidt biplane Schmidt may refer to: * Schmidt (surname), including list of people with the surname * Schmidt (singer) (born 1990), German pop and jazz singer * Schmidt (lunar crater), a small lunar impact crater * Schmidt (Martian crater), a crater on Mars * ...
, also in 1913. A patent for a rigid variable-incidence wing was lodged in France on 20 May 1912 by
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...
n inventor George Boginoff. It is believed that four unsuccessful Russian types were built between 1916 and 1917. The
Zerbe Air Sedan The Zerbe Air Sedan was an American single engine quadruplane passenger aircraft project started by Professor James Slough Zerbe in 1918. The machine made one flight in 1921, was damaged during landing, and was subsequently abandoned. Design an ...
was a tandem
quadruplane In aviation, a multiplane is a fixed-wing aircraft-configuration featuring multiple wing planes. The wing planes may be stacked one above another, or one behind another, or both in combination. Types having a small number of planes have specific nam ...
which flew only once, in 1921. The first example to be made in any quantity was the French tandem-wing Mignet Pou du Ciel (Flying Flea), which became briefly popular during the 1930s. It had a variable-incidence forewing which proved unsafe, and sales were discontinued following a series of fatal crashes. During World War II, the German company
Blohm & Voss Blohm+Voss (B+V), also written historically as Blohm & Voss, Blohm und Voß etc., is a German shipbuilding and engineering company. Founded in Hamburg in 1877 to specialise in steel-hulled ships, its most famous product was the World War II battle ...
developed the variable-incidence monoplane to provide increased lift at takeoff, where the rear fuselage was too close to the ground to allow rotation of the whole aircraft. The fuselage of the BV 144 prototype transport sat low on a short undercarriage, allowing passengers to go on and off without the need for additional steps. Another proposal by B&V, the P 193 attack aircraft, was of
pusher configuration In an aircraft with a pusher configuration (as opposed to a tractor configuration), the propeller(s) are mounted behind their respective engine(s). Since a pusher propeller is mounted behind the engine, the drive shaft is in compression in nor ...
and could not rotate its fuselage for takeoff without the propeller fouling the ground, so it was given a variable-incidence wing.Hermann Pohlmann; ''Chronik Eines Flugzeugwerkes 1932-1945'', Motorbuch, 2nd Impression, 1982. Russian designer S. G. Kozlov designed the E1 variable-incidence fighter, but the unfinished prototype was destroyed when the factory was overrun by Germany in 1941.Yefim Gordon and Bill Gunston; Soviet X-Planes, Midland, 2000, p.83.
Carrier-borne aircraft Carrier-based aircraft, sometimes known as carrier-capable aircraft or carrier-borne aircraft, are naval aircraft designed for operations from aircraft carriers. They must be able to launch in a short distance and be sturdy enough to withstand ...
must have good forward visibility during the descent and approach for a deck landing. Without a variable-incidence wing (or other
high-lift device In aircraft design and aerospace engineering, a high-lift device is a component or mechanism on an aircraft's wing that increases the amount of lift (force), lift produced by the wing. The device may be a fixed component, or a movable mechanism w ...
), the pilot must pitch up the entire aircraft to maintain
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 ...
at the slow approach speed required, and this can restrict forward vision. By increasing the incidence of the wing but not the fuselage, both high lift and good forward vision can be maintained. The device also avoids the need for a long, bulky and heavy nose undercarriage to raise the angle of attack at takeoff. The
Supermarine Type 322 The Supermarine Type 322 was a prototype British carrier-borne torpedo, dive bomber and reconnaissance aircraft of the Second World War. A single-engined monoplane, it was unsuccessful, with only two examples being built. The Fairey Barracuda, ...
prototype flew in 1943, and the Seagull ASR.1 amphibian flying boat in 1948.Jarrett, Philip. "Nothing ventured", Part Five, ''Aeroplane Monthly'', August 1990, pp.456-459. After the war the USA revisited the idea for the jet age. The
Martin XB-51 The Martin XB-51 was an American trijet ground-attack aircraft. It was designed in 1945 and made its maiden flight in 1949. It was originally designed as a bomber for the United States Army Air Forces under specification V-8237-1 and was desi ...
bomber and the
Republic XF-91 The Republic XF-91 Thunderceptor (originally designated XP-91) is a mixed-propulsion prototype interceptor aircraft, developed by Republic Aviation. The aircraft would use a jet engine for most flight, and a cluster of four small rocket engines ...
interceptor adopted variable incidence for much the same reason as B&V. Both first flew in 1949, but only a handful of prototypes of either was built. They were followed in 1955 by the
Vought F-8 Crusader The Vought F-8 Crusader (originally F8U) is a single-engine, supersonic, carrier-based air superiority jet aircraft built by Vought for the United States Navy and United States Marine Corps (replacing the Vought F7U Cutlass), and for the Frenc ...
carrier-borne jet fighter, the only variable-incidence type to go into production and enjoy a successful service career.


See also

*
Stabilator A stabilator is a fully movable aircraft horizontal stabilizer. It serves the usual functions of longitudinal stability, control and stick force requirements otherwise performed by the separate parts of a conventional horizontal stabilizer and el ...
- a variable-incidence horizontal stabilizer or tailplane. *
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 typical ...
- a type of
vertical takeoff Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff. For aircraft that take off horizontally, this usually involves starting with a t ...
plane which tilts its wings and engines. *
Variable camber wing Variable camber is a feature of some of aircraft wings that changes the camber (or curvature) of the main aerofoil during flight. In one system, the leading and/or trailing edge sections of the whole wing pivot to increase the effective camber of ...
- in which the aerofoil profile is changed rather than tilted.


References

{{reflist, refs= {{cite patent, country=FR, number=444010 Aircraft configurations Variable-geometry-wing aircraft Aircraft wing design Wing configurations