Design and development
In 1949 the Yak-20 was designed by the OKB for use with aviation clubs as a trainer and sport aircraft. Intended to be the cheapest modern aircraft that could serve as a useful pilot trainer and aerobatic sport aircraft, the Yak-20 was intended to be considerably cheaper to build and operate than the contemporary Yak-18.
Though structurally similar to the Yak-18, the Yak-20 had a welded steel tube fuselage which was skinned with aluminium alloy sheet and fabric, with Aluminium alloy wings, skinned in metal back to the single spar, and fabric aft of the spar. Accommodation was side by side under a large blown canopy, which slid open to the rear. The cockpit had dual stick controls, with the pilot sitting to port. There was a central push-pull throttle, and simple gyro instruments. The engine was the newly developed Ivchenko AI-10 five cylinder radial. This engine was small, and extremely light. It was rated at 80hp, driving a V-515 controllable-pitch counterweight propeller. Fuel was carried in two 35 liter (7.7 gallon) tanks in the wing roots, ahead of the single spar.
The Yak-20 was designed from the start to be fully aerobatic with very high spin resistance. The two prototypes were tested by pilots Anokhin and Georgii Shiyanov, and later by DOSAAF pilots, as well as a succession of leading aerobatic sport pilots who were invited to fly it. All were eager to see it put into production. State Acceptance trials followed, but the State evaluation team considered the Yak-20 too small and under-powered, recommending a redesign to match the performance of the Yak-18. Some of the criticisms of the State evaluation team were addressed in the second prototype, (Yak-20-2), which, as a result, became heavier and lost the performance edge of the first prototype. With Yak-18 production already in full swing, production of the Yak-20 was deemed superfluous. The final blow came when production of the small Ivchenko AI-10 engine was cancelled.
- First Prototype.
- Second Prototype
- Crew: two, student and instructor
- Length: 7.06 m (23 ft 2 in)
- Wingspan: 9.56 m (31 ft 4 in)
- Height: ()
- Wing area: 15.0 m² (161.5 ft²)
- Empty weight: 470 kg (1,040 lb)
- Loaded weight: 700 kg (1,540 lb)
- Max. takeoff weight: 700 kg (1,540 lb)
- Powerplant: 1 × Ivchenko AI-10 5 cyl. radial automatic variable pitch, 59.7 kW (80 hp)
- Maximum speed: 160 km/h (100 mph)
- Range: 400 km (249 miles)
- Service ceiling: 3,000 m (9,850 ft)
- Rate of climb: m/s (ft/min)
- Wing loading: 48.66 kg/m² (9.43 lb/ft²)
- Power/mass: 0.085 kW/kg (0.052 hp/lb)
- Gunston, 1997
- Gordon, Yefim (2005). OKB Yakovlev: A History of the Design Bureau and its Aircraft. Hinkley: Midland.
- Gunston, Bill. Yakovlev Aircraft since 1924. London, UK: Putnam Aeronautical Books, 1997. ISBN 1-55750-978-6.