Yak-36 – the birth of Soviet aircraft with vertical takeoff and landing

Photo by Creative Commons license

Vertical take-off and landing (VTOL) aircraft were of great interest to both aircraft designers and potential operators. In 1947, Konstantin Shulikov, an engineer at the Experimental Design Bureau-155 (now Yakovlev PJSC), patented an aircraft with a fixed turbojet engine whose nozzle was split into two symmetrical channels with vertically rotatable nozzles at the ends.

To bring this idea to life managed to Design Bureao of Alexander Yakovlev. A single-seat prototype aircraft in the size of a fighter-bomber was selected from several proposed variants, on which the power plant and control system would be worked out.

A prerequisite for the realisation of plans to create a hovercraft was the emergence of a lightweight and compact R19-300 TRD. In 1960, Alexander Yakovlev came out with a proposal to develop the Yak-104 aeroplane. The project envisaged the use of two boosted R19-300 engines with a thrust of 1600 kgf each as a lifting and marshalling engines and one lifting R19-300 with a thrust of 900 kgf. It was expected that with a flight weight of 2800 kg and a fuel reserve of 600 kg, the hovercraft would be able to fly at a maximum speed of 550 km/h, climb to an altitude of 10,000 m and have a range of 500 km with a flight time of 1 hour 10 minutes.

Given the great technical difficulties of creating a hovercraft, as well as the complete lack of experience in this matter, Alexander Yakovlev and chief designer of the Experimental Design Bureau-300 Sergei Tumansky proposed at the first stage of work to create a single-seat prototype aircraft type fighter-bomber for the study of piloting techniques and combat use. The aircraft was to be built with two R21M-300 engines. The engine was designed with a rotary nozzle.

Photo by Creative Commons license

For further development of work on the VTOL Yakovlev and Tumansky proposed to work on the creation of an aircraft with a greater flight weight and a more powerful propulsion system. The new propulsion system was based on the R21M-300 with equipment and turbofan unit, which provided vertical thrust up to 10,000 kgf. An aircraft with such a propulsion system could have a take-off weight of up to 18,000 kilograms.

The project, first designated Yak-V (product “B”) and later Yak-36, was adopted for practical implementation. A draft decree of the Council of Ministers on the development of a single-seat fighter-bomber with two R21M-300 engines of 5000 kgf thrust was prepared in April 1961. The aircraft was designed to fly at a maximum speed of 1100-1200 km/h at an altitude of 1000 metres. Take-off weight was not to exceed 9150kg. The rest of the design characteristics were retained. In the process of modernising the propulsion system, the Tumansky Design Bureau created the R27-300 TRD, which was installed on the Yak-36.

Four machines were built at Plant No. 115 on Leningradsky Prospekt of the capital, one of which was intended for strength tests. In the spring of 1963, the first aircraft with the flight number 36 began research into the means of protecting the engines from being hit by a reflected jet and resource tests. On Yak-36 for this purpose provided two gas-reflecting shields, one in the nose, and the other – in front of the nozzles TRD.

On the second machine with the tail number 37, take-offs and landings were practised, first on a tether up to half a metre height, and then in free-hanging mode at heights up to five metres. The pace of work is evidenced by the fact that 85 hovering operations were performed in two years.

On the third aircraft (borne number 38) was tested during the climb on the cable screen the effectiveness of improvements to the jet rudders, autopilot and recomposed controls in the cockpit. Such air consumption rates were selected, which gave the aircraft stability at hover and made the machine obedient to the pilot’s will.

Photo by Creative Commons license

On 27 July 1964, the first flight of the Yak-36 took place with take-off and landing “in the aircraft way”, and on 27 September 1964 – the first free hover with transition to horizontal flight. It was performed by test pilot Valentin Mukhin of OKB-115. However, the flight with vertical takeoff and landing was first performed only on 24 March 1966.

In July 1967, at an aviation parade in Domodedovo Yak-36 demonstrated the ability to take off and land vertically, and Yakovlev appealed to the government with a proposal to produce 10-15 Yak-36 to develop the methodology of operation of such machines on the ship. However, this proposal was rejected by the military – the USSR Ministry of Defence was not interested in an aircraft with minimal payload. As a result, the idea arose to use this aircraft on a Soviet aircraft carrier.

On 18 November 1972, test pilot Mikhail Dexbach made the first landing on the ship, and on 22 November flew “full profile” – vertical launch from the deck, horizontal flight and vertical landing on the deck.

However, insufficient payload made this VTOL unpromising, and the Yakovlev Design Bureau began development of the Yak-36M combat aircraft, with a more powerful R27V-300 lift-marshalling engine and two RD-36-35FV lift engines developed by the Sergei Tumansky Design Bureau. This deeply modernised aircraft, which later received the Yak-38 index, was built in series. The layout of the new machine was radically different from its predecessor, becoming a classic for domestic VTOLs.