The Yakovlev Yak-52 (Як-52) is a Soviet primary trainer aircraft which first flew in 1976. It is still being produced in Romania by Aerostar, which gained manufacturing rights under agreement within the now defunct COMECON socialist trade organisation. The Yak-52 was designed originally as an aerobatic trainer for students in the Soviet DOSAAF training organisation, which trained both civilian sport pilots and military pilots.
Since the early 1990s and the fall of the Soviet Union, many Yak 52s have been exported to the west. Of the approximately 1,800 produced to date, most now fly in the United States, United Kingdom, New Zealand, Australia and other western countries.
Design and development
A descendant of the single-seat competition aerobatic Yakovlev Yak-50, the all-metal Yak-52 is powered by a 268 kW (360 hp) Vedeneyev M14P 9-cylinder radial engine. The aircraft has inverted fuel and oil systems permitting inverted flight for as long as two minutes. The engine drives a two-bladed counter-clockwise rotating, variable pitch, wood and fiberglass laminate propeller.
At 998 kg (2,200 lb) empty weight, the Yak-52 is responsive and very capable as an aerobatic aircraft. Yet it is also easy to fly and land. It has been used in international aerobatic competition up to the Advanced level. It is stressed to +7 and –5 Gs, rolls (to the right) at 180 degrees/second and is capable of every manoeuvre in the Aresti catalog.
The Yak-52, like most Soviet military aircraft, was designed to operate in rugged environments with minimal maintenance. One of its key features, and a radical departure from most western aircraft, is its extensive pneumatic system. Engine starting, landing gear, flaps, braking and steering are all pneumatically actuated. Spherical storage bottles for air, replenished by an engine driven compressor, are situated behind the rear cockpit and contents displayed on the instrument panels. The operating pressure is between 10 and 50 bars (145 and 725 psi) and an emergency circuit is reserved for lowering the undercarriage if the normal supply is exhausted or the compressor fails. Additionally both main and reserve bottles can be charged from a port on the ground with compressed air, usually from a SCUBA type air bottle. The steering/braking arrangement, especially, takes some adjustment for flyers accustomed to hydraulics, because the plane uses differential braking controlled by rudder pedals and a hand operated lever on the control stick.
The tricycle landing gear is fully retractable, but it remains partially-exposed in the retracted position, affording both a useful level of drag in down manoeuvres and a measure of protection should the plane be forced to land "wheels up."
A number of "westernised" versions of the Yak-52 are now produced. The replacement of the existing Soviet avionics, fitting of a three-blade aerobatic propeller (Yak-52W) and conversion to conventional "tail-dragger" landing gear (Yak-52TD) are the major modifications to the standard aircraft. There is also a factory produced Yak-52TW tail-dragger version which looks like a small Yak-11. The TW has some nice features such as an extra 120 l (32 US gal) of fuel capacity in two extra wing tanks, a 298 kW (400 hp) engine designated M-14PF, an electric start, and modern instruments.
On April 16, 2004, a modernised variant Yak-52M was flown in Russia. It is fitted with modernised M-14Kh engine, three-blade propeller, ejection seats and other modifications.
Specifications (Yak 52)
Published in July 2009.
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