Yakovlev Yak-36
| Yak-36 | |
|---|---|
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| Yak-36 undergoing a demonstration flight before the Domodedovo Air Show in 1967 | |
| Role | Experimental VSTOL aircraft |
| National origin | Soviet Union |
| Manufacturer | OKB Yakovlev |
| First flight | 9 January 1963 |
| Number built | 4 |
The Yakovlev Yak-36, also known as Izdeliye V, (NATO reporting name "Freehand") was a Soviet technology demonstrator for a VTOL combat aircraft.
From 1960, the Yakovlev Design Bureau began work on a VTOL system, using the compact and lightweight Tumansky RU-19-300 turbojet engine, drafting a proposal for the Yak-104, a converted Yak-30 jet trainer with two vertically mounted Ru-19 engines between the inlet ducts of the standard Yak-30 powerplant. Work on the Yak-104 was terminated in favour of an aircraft with a single lift/cruise engine with rotating nozzles, similar to the Hawker Siddeley P.1127, which was nearing completion in England. Unable to find a suitable engine or convince the government to order the development of one, the Yakovlev bureau was forced to follow a different course.
In response to a contract for the development of a single-seat V/STOL fighter in 1961, Yakovlev proposed a twin-engined aircraft with a large nose air intake, engines in the forward fuselage and swivelling exhaust nozzles, one for each engine on either side of the lower fuselage near the centre of gravity of the aircraft. The fighter version was not proceeded with but four technology demonstrators, (initially designated Izeliye V) based on the fighter studies were ordered.
Four prototypes were completed, one of which was used only for static testing. The second was used for takeoff and landing tests, including free hovering. The third incorporated improvements found in testing, including an improved autopilot which automatically selected optimal air flow for hover stability. This prototype crashed, but was later rebuilt. The fourth prototype crashed in February 1971 and was not rebuilt.
The airframe had a semi-monocoque fuselage with bicycle-type landing gear, short cropped delta wings of 37° leading edge sweep, with 5° anhedral, attached to the fuselage in a mid position. The fuselage was substantial forward of the wing trailing edges, due to accommodating the engines, cockpit, fuel tanks and equipment bays as close to the centre of gravity as possible, tapering sharply to the swept tail surfaces with a high-set tailplane. Control of the aircraft was by conventional rudder, ailerons and elevators in normal flight and by compressed engine bleed air blown from control nozzles at the wingtips, rear fuselage tip and at the end of a long boom extending forwards from the top lip of the air intakes.
Two underwing hard points could carry bombs, podded machine guns or rocket pods, but the Yak-36 had insufficient excess thrust and range for effective use as a combat aircraft.
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