The Yakovlev Yak-36 is a prototype of a vertical take-off and landing (VTOL) military aircraft developed by the Soviet Union to showcase their technological capabilities.
Starting in 1960, the Yakovlev Design Bureau embarked on the development of a VTOL (Vertical Take-off and Landing) system.
They utilized the Tumansky RU-19-300 turbojet engine, known for its compactness and lightweight, to propose the Yak-104.
This involved converting the Yak-30 jet trainer by installing two Ru-19 engines in a vertical configuration between the inlet ducts of the standard Yak-30 powerplant.
However, the Yak-104 project was abandoned in favour of an alternative aircraft design that featured a single lift/cruise engine with rotating nozzles, similar to the Hawker Siddeley P.1127, which was nearing completion in England.
Unfortunately, the Yakovlev bureau faced challenges in finding a suitable engine or convincing the government to support the development of one, ultimately leading them to pursue a different direction.
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 prominent nose air intake, forward fuselage-mounted engines, and swivelling exhaust nozzles.
Each engine was positioned on either side of the lower fuselage, near the aircraft’s centre of gravity.
Although the fighter version did not progress further, four technology demonstrators were ordered based on the initial fighter studies, initially designated as Izdeliye V.
Four prototypes were successfully constructed, with one solely utilized for static testing. The second prototype underwent take-off and landing tests, including free hovering.
The third prototype incorporated improvements identified during testing, including an enhanced autopilot system that automatically selected the optimal air flow for hover stability.
Unfortunately, this particular prototype experienced a crash but was later reconstructed. Regrettably, the fourth prototype crashed in February 1971 and was not rebuilt.
The Yak-36 featured a semi-monocoque fuselage and bicycle-type landing gear, along with short cropped delta wings that had a 37° leading edge sweep and 5° anhedral.
These wings were attached to the fuselage in a mid-position.
The fuselage itself was substantial forward of the wing trailing edges, as it needed to accommodate the engines, cockpit, fuel tanks, and equipment bays as close to the centre of gravity as possible.
It then tapered sharply to the swept tail surfaces, which included a high-set tailplane.
Control of the aircraft was achieved through conventional rudders, ailerons, and elevators during normal flight.
However, compressed engine bleed air was also used for control, which was blown from control nozzles located at the wingtips, rear fuselage tip, and at the end of a long boom extending forwards from the top lip of the air intakes.
The Yak-36 also had two underwing hard points that could carry bombs, podded machine guns, or rocket pods. However, due to its insufficient excess thrust and range, it was not an effective combat aircraft.
The inaugural tethered hover flight occurred on 9 January 1963, but it was not without its initial challenges.
One of the primary issues encountered was the reingestion of hot gas, whereby the hot exhaust gasses were drawn back into the intakes, resulting in inadequate airflow through the engines and a subsequent loss of thrust.
Additionally, the suction effect of the exhaust on the ground necessitated higher engine power, further complicating matters.
Control system problems compounded these difficulties.
However, modifications were implemented, leading to the first untethered vertical flight on 23 June 1963, followed by the momentous achievement of the first complete transition to horizontal flight on 16 September 1963.
A significant milestone was reached on 24 March 1966 when the aircraft successfully completed a full flight encompassing vertical take-off, transition to horizontal flight, deceleration to vertical flight, and ultimately, vertical landing.
Following extensive testing and refinement, the Yak-36 made its inaugural public appearance on 9 July 1967 at the Moscow-Domodedovo airport air show, commemorating the 50th anniversary of the October Revolution.
Encouraged by the promising outcomes derived from the Yak-36’s flight test program, the subsequent developmental phase involved the Yakovlev Yak-36M, which took to the skies for the first time on 27 September 1970. Specifications Yak-36 Crew One Length 17 m (55 ft 9 in) Wingspan 10 m (32 ft 10 in) Height 4.5 m (14 ft 9 in) Wing area 17 m2 (180 sq ft) Empty weight 5,300 kg (11,684 lb) Max take-off weight 8,900 kg (19,621 lb) Fuel capacity 2,600 kg (5,732.02 lb) Powerplant 2 × Tumansky R-27-300 Vectored thrust axial flow turbojets, 51.993 kN (11,688 lbf) thrust each Performance Maximum speed 900 km/h (560 mph, 490 kn) Range 370 km (230 mi, 200 nmi) Service ceiling 12,000 m (39,000 ft) Hovering ceiling 1,900 m (6,233.60 ft) Rate of climb 140 m/s (28,000 ft/min) Armament Guns 2 x 23 mm (0.91 in) GSh-23L cannon (UPK-23-250 gunpods) Hardpoints 2 with a capacity of 100kg, with provisions to carry combinations of: Rockets S-5K Missiles R-3S air-to-air missiles Bombs FAB-100 and FAB-250 Rockets 2 x UB-16-57UM FFAR rocket pods (16 rockets each) Sources Yakovlev Aircraft Since 1924 – Bill Gunston & Yefim Gordon. OKB Yakovlev, A History of the Design Bureau and its Aircraft-Yefim Gordon, Dmitriy Komissarov & Sergey Komissarov. Soviet Aircrafts Illustrated-A.S.Yakovlev. The History of Soviet Aircraft from 1918-Vaclav Nemecek. Soviet AF Fighter Colours 1941-45-Erik Pilaeskii. Soviet Combat Aircraft of the Second World War, Vol 1, Single Engined Fighters-Yefim Gordon and Dmitri Khazanov. Early Soviet Jet Fighters, The1940s and early 50s-Yefim Gordon.
