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Yakovlev Yak-36M

Published on May 23, 2012,

A project intended to meet this requirement was prepared in 1968. The aircraft was to be powered by two R27VM-300 lift/cruise engines with thrust-vectoring nozzles placed under the wing roots, which were similar to those of the Yak-36; it had an elongated fuselage with a pointed nose and lateral intakes. This project was abandoned in favour of a machine with a composite powerplant and subsonic performance. The new aircraft was allocated the in-house designation izdeliye VM. Its development was conducted under the direction of S. Mordovin as project manager.

Officially the new aircraft was designated Yakovlev Yak-36M (despite the fact that structurally it had nothing in common with the Yak-36). Possibly this was a ploy aimed at securing state funding for the new aircraft. It would have been hard to persuade MAP to finance development of a ‘clean sheet of paper’ VTOL fighter if the ministry got the idea that the Yak-36 had been a failure and a waste of money. Therefore, quite possibly the OKB wanted to pass the new machine off as a ‘modification’ of the existing design. The meaning of the M suffix in this case is ambiguous. According to the prevailing opinion among the OKB’s staff, this letter stands for morskoy (naval), but it can also be interpreted more traditionally as modernizeerovannyy (upgraded).

The powerplant of the izdeliye VM was radically different from that of the Yak-36. It comprised two types of engines differing in the direction of their thrust. The main engine was a lift/cruise engine; it contributed to providing lift in the take-off and landing mode by means of vectoring nozzles. In these flight modes additional lift was provided by two special lift engines placed almost vertically in a tandem arrangement behind the cockpit; they were slightly inclined forward. After lifting off vertically, the aircraft would perform a transition to horizontal flight, gradually reducing the thrust of the lift engines to complete shutdown in the course of this transition. At the same time the vectoring nozzles of the main engine would be gradually rotated into horizontal position. It was clear that precise balancing of the lift engines’ thrust during take-off and landing would be hard to achieve manually; therefore, it was considered necessary to automate fully this process with the help of a specially designed SAU-36 automatic control system (sistema avtomaticheskovo oopravleniya).

The main lift/cruise engine was again obtained by adapting the R27-300 turbojet which in its modified version received the designation R27V-300 (izdeliye F). It was a two-spool engine with an axial compressor comprising five LP stages and six HP stages, an annular combustion chamber, a two-stage turbine with cooled guide vanes and blades of the HP stage, and a curved bifurcated jetpipe with two tapering rotating nozzles actuated by hydraulic motors. During the bench tests the thrust was initially slightly in excess of 6,000 kgp (13,230 Lbst); later, in the course of series production of the Yak-38, the thrust rating was raised (in a modified version) to 6,800 kgp (14,990 Lbst).

The lift engines selected for the Yak-36M were RD36-35 turbojets developed at the Rybinsk Engine Design Bureau (RKBM) under the direction of Pyotr A. Kolesov. They had already been tested in Sukhoi’s and Mikoyan’s experimental aircraft with mixed powerplants. The RD36-35 had a six-stage compressor and a single-stage turbine; during bench tests the engine weighing 176 kg (388 lb) delivered a thrust of 2,350 kg (5,182 lb). The uprated version used on the Yak-36M was designated RD36-35FV (the suffix is sometimes given as VF); it had a thrust rating of 2,900 kgp (6,395 lbst).

The fuselage was totally different from the Yak-36′s, with a much higher fineness ratio and a pointed nose. The main engine drew air through semi-oval cross-section lateral air intakes just aft of the cockpit (provided at a later stage with a row of auxiliary blow-in doors), exhausting through a bifurcated jetpipe with two small vectoring nozzles. The latter were joined by a transverse synchronising shaft. The two lift engines were enclosed in cruise flight by an aft-hinged cover with spring-loaded blow-in doors; it opened during take-off and landing to act as an air scoop. The jet orifices were closed in cruise flight by twin doors. The fuel was housed in two integral fuselage tanks; one of these was placed between the lift engines and the main engine; the other was accommodated in the rear fuselage.

The tricycle undercarriage comprised single-wheel main units retracting forward into the fuselage, the wheels rotating around the oleos in so doing, and an aft-retracting castoring single-wheel nose unit. The wheel track on the prototypes and the first ten production machines was 2.2 m (7 ft 2 in); on subsequent aircraft it was increased to 2.75 m (9 ft 0 in), the main gear units being redesigned to feature a fairly complex retraction sequence.

Yakovlev Yak-36MProduction Yak-36Ms manufactured by the Saratov plant were used either for various kinds of special tests or for the training of AVMF pilots. A shipboard aviation regiment was formed with Feoktist Matkov-skiy as its first commander. By the spring of 1975 the first Soviet aircraft-carrying cruiser SNS Kiev was ready for shipboard testing of the Yakovlev Yak-36M attack aircraft.

The test programme was started with the VM-02 in which factory test pilots practised landings and take-offs on the cruiser’s deck. This training lasted from March until October; then came the turn of service pilots. On 15th December 1975 the regiment’s commander Matkovskiy made the first landing on the deck of the Kiev. This marked the beginning of endowing the carrier with operational capability.

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