Yak 52 History

Yak 52 History by Mark Schrick

Among the aircraft manufacturers from the former USSR, the OKB A.S. Yakovlev developed a wide range of types, from small light trainers (UT-2, Yak-18, Yak-50,-52,-53,-54,-55), to fighters equipped with piston engines (Yak-1,-3,-7,-9) or jet engines (Yak-15,-17, -19, -21,-23,-25,-28 ), including VTOL fighters (Yak-36,-38,-141) and to business/regional transport aircraft (Yak-40, Yak-42).

In 1972 was flown the prototype of Yak-50, a single-seater, aerobatics aircraft, derived from the IAK-18 basic trainer, with an all metal structure with duraluminium skin, except on the control surfaces fabric covered; the wing central section as on Yak-18 series was eliminated, the attachment of the wings being made directly to the sides of the fuselage. The Yak-50 prototype had fixed undercarriage, but for the production aircraft a semi-retractable landing gear was adopted, similar to that on the Yak-18. The new aircraft was equipped with a Vedeneyev M-14P, 9 cylinders radial air-cooled engine, rated at 360hp, a supercharged version of AI-14. By the introduction of some elements from Yak-18A (tandem cockpit, canopy, semi-retractable tricycle undercarriage- which prevents the damage of the under side of the fuselage and wings in case of "wheels-up" landing) in the new design of Yak-50, resulted the design of Yak-52 trainer. The aircraft was intended to replace the Yak-18 of the DOSAAF; a necessary of 1000 aircraft was estimated for the following 10 years.

For the production of the aircraft was selected I.R. Av. Bacau (I.Av. Bacau from 1978 and Aerostar S.A. since 1991). This company had already a long experience in the overhaul of military jets (Yak-17, -23, MiG-15, -17, -19, -21, IL-28) and was main contractor in the construction and testing of the prototype of the IAR-93 ground attack aircraft - the first major military aircraft program in Romania after the end of the WW2, under a joint program with Yugoslavia. The detailed design started in URSS in 1975 and the technical documentation started to arrive in 1976 and it was translated. The factory began also the construction of the assembly jigs. The initial design featured stringers spot-welded to the wing cover panels, as well as rivets with countersink. Because these two technologies proved to be non-economical, their use in the production process was abandoned. The Soviet prototype was brought from USSR in the deck of an AN-12. The aircraft was never flown in Bacau, being used only as a mockup.

The manufacturing of the first Romanian prototype started in 1977 within the airframes overhaul facility of I.R.Av., while in the plant specialized in the production of landing gears, hydraulic& pneumatic equipment of I.R.Av. started the production of the landing gear for Yak-52, as well as of the components of the aircraft pneumatic system.
The Romanian prototype ( c/n 780102) was finished and rolled out on April 28, 1978. After several ground tests, the first engine runs were made on May 9, 1978 and around May 20 performed its first unofficial flight with the pilot Teodor Coman at controls. At that time the aircraft was not painted and was provisionally registered to the Romanian Air Force as Red 0102. It was later painted in the colors of DOSAAF and registered as Yellow 01. It was handed-over to the Soviets after the official reception flight performed on July 22, 1978 by Dmitri Mitikov, test pilot of Yakovlev OKB. After the manufacturing of a first batch of 2 aircraft till the end of 1978 (c/n 780102 - "01" and 780103 - "02"), plus an airframe for static tests (c/n780101), and another for dynamic tests (c/n 780104) in the following year was started the series production, at first with aircraft c/n 790105 (01) followed by 2 batches of 5 aircraft, 5 batches of 10 aircraft, and all the following batches had 15 aircraft.

Although the intergovernmental agreement provisions allowed deliveries of the aircraft to Eastern Block countries, after completing the deliveries to the USSR, due to the huge quantity order by the Soviets, they were the only customers of the aircraft during that period.

In USSR the aircraft were used within the air clubs of DOSAAF paramilitary sport flying organization and was used as basic trainer for students often not older than 14-15. The official entry in DOSAAF service took place on May 8, 1979 on Tushino airfield. The first DOSAAF pilots to fly the Yak-52 were Kasum Najmutdinov - the trainer of the aerobatics team of USSR and Yuri Komitzin - the Chief of the Central Air club.
In the '80s the only customer for Yak-52, except USSR, was the Romanian Air Force, which introduced the aircraft at the beginning of 1986 as IAK-52 in the inventory along the IAR-823 basic trainer within Air Liaison Group, based on Focsani airfield, at that time part of the Scoala Militara de Ofiteri de Aviatie "Aurel Vlaicu" (The Military Aviation School) of Bobocu-Buzau, 23 aircraft being delivered in the following years. Today, the unit is subordinated to the Romanian Air Force Academy "Henri Coanda", which took over all the assets of the former military school during the reorganization process held in 1995.

During the manufacturing process, the aircraft was subject to certain upgrades, as follows:
- the rounded wingtip, made from welded metal sheet was removed, starting with the 16th aircraft (c/n 790301). So, the wingspan was reduced from 9.5m to 9.3 m.
- the installation of a stall speed sensor and warning SSKUA-1A , starting with aircraft c/n 822801 and also for the aircraft already delivered, starting with c/n 800901.
- the replacement of the Landis-5 radio station with Baklan-5, starting with the 121st delivered aircraft (c/n 801101).
- the replacement of the Varley battery with 12ASAM-23 starting from c/n 822502 in production, as well as for all the aircraft already delivered.
- the reinforcement of the wing spar attachment joints to the fuselage was introduced on aircraft c/n 866501 (rolled out in April 1986) following the Service Bulletins 59R and 60R.