Gribovsky G-20

Gribovsky G-20
Role	Two seat trainer
National origin	USSR
Designer	Vladislav Gribovsky
First flight	1935
Number built	1

The Gribovsky G-20 (Russian: ГРИБОВСКИЙ Г-20) was an aerobatic trainer, designed in the USSR in the mid-1930s. Only one was built; re-engined in 1937, it was used to train many aerobatic pilots.

Design and development

The G-20 was a monoplane with a low wing of semi-elliptical plan, its greatest chord some way out from the roots. Unusually, the wing was braced from above with a pair of inverted V steel struts to a crash pylon within the enclosed forward cockpit. The wing had long, broad chord ailerons and manually operated flaps.^[1]^[2]

On its first flight, in 1935, and over its early career it was powered by a five-cylinder Shvetsov M-11 radial engine, a Soviet design which originally produced 100 hp (75 kW),^[1]^[3] enclosed in a broad chord, helmeted cowling. In 1937 performance was improved with the installation of an uprated M-11 variant, the 150 hp (112 kW) M-11 Ye. Behind the engine the fuselage was deep and rounded below. Instructor and student were in tandem cockpits under continuous, multiframed glazing that merged into a raised rear upper fuselage.^[1] Its empennage was conventional, with elliptical, mid fuselage horizontal surfaces, the tailplane braced from the upper fuselage. The fin merged smoothly into the fuselage and carried a broad, unbalanced rudder which extended own to the keel. The tailplane was far enough forward that trailing edges of the elevators were ahead of the rudder hinge.^[2]

The G-20 had a tailwheel undercarriage. Its main wheels, mounted on slender cantilever legs, were enclosed in large, deep spats.^[1]

It flew for the first time in 1935. It came third in the first All-Union light competition but was initially underpowered for its aerobatic trainer rôle.^[2] Its performance was much enhanced by the more powerful M-11 Ye engine^[1] and subsequently some seventy pilots qualified on it.^[2]

Specifications (M-11 Ye engine)

Data from Gunston (1965), p.79 ^[1]

General characteristics

Crew: Two
Length: 6.3 m (20 ft 8 in)
Wingspan: 9.7 m (31 ft 10 in)
Wing area: 13.2 m² (142 sq ft)
Airfoil: RII
Empty weight: 620 kg (1,367 lb)
Gross weight: 880 kg (1,940 lb)
Fuel capacity: 100 kg (220 lb), including oil
Powerplant: 1 × Shvetsov M-11 Ye 5-cylinder radial, 110 kW (150 hp)

Performance

Maximum speed: 235 km/h (146 mph, 127 kn)
Range: 400 km (250 mi, 220 nmi) :This and below refer to original M-11 engine
Service ceiling: 3,870 m (12,700 ft)
Time to altitude: 11.1 min to 2,000 m (6,562 ft)
Take off distance: 190 m (623 ft)
Landing speed: 70 km/h (43 mph)

References

^ ^a ^b ^c ^d ^e ^f Gunston, Bill (1995). The Osprey Encyclopedia of Russian Aircraft 1875–1995. London: Osprey (Reed Consumer Books Ltd). p. 79. ISBN 1 85532 405 9.
^ ^a ^b ^c ^d "Gribovsky G-20". Retrieved 4 November 2014.
^ Gunston (1995). The Osprey Encyclopedia of Russian Aircraft 1875–1995. pp. XX–XXI.

[Russ-1] ^ ^a ^b ^c ^d ^e ^f Gunston, Bill (1995). The Osprey Encyclopedia of Russian Aircraft 1875–1995. London: Osprey (Reed Consumer Books Ltd). p. 79. ISBN 1 85532 405 9.

[av-mu-2] "Gribovsky G-20". Retrieved 4 November 2014.

[RussM11-3] Gunston (1995). The Osprey Encyclopedia of Russian Aircraft 1875–1995. pp. XX–XXI.

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