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.
Since the aircraft was destinated to serve as a military trainer, the development of the aircraft incorporates a number of features to be found on the early post-war fighters: to be noted that the cockpit tandem layout (instruments panel, seats design, opening system of the cockpit), tail design, tri-cicle landing gear, fuselage mixed construction (monocoque with steel tube construction), inner flaps, controls position, access panels on sides of the fuselage, even the location of the radio antena and overall dimensions of the airplane, strikingly match with the Yakovlev Yak-17 UTI jet fighter trainer (NATO code name Magnet).
Indeed we can believe the fact that Yakovlev design bureau, at the time of aircraft conception, had in mind a more economical and easier to mantain "Yak-17 UTI piston engine version" for the military.
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, unusual in western aircraft, is its extensive pneumatic system. Engine starting, landing gear, flaps, and wheel brakes 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 ground 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 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 propeller and the M14PF 298 kW (400 hp) upgrade to the usual 360 hp M14P engine, and conversion to conventional "tail-dragger" landing gear (Yak-52TD) are some of the modifications made to the standard aircraft. There is also a factory produced Yak-52TW tail-dragger version. The TW has an extra 120 l (32 US gal) of fuel capacity in two extra wing tanks, the M14PF engine designated & three blade propeller, 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, and other modifications.
Read more about this topic: Yakovlev Yak-52
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