Yakovlev EG

Yakovlev EG / Sh / Yak-M11FR-1
Role	Experimental helicopter
Manufacturer	Yakovlev
First flight	1947
Number built	1

The Yakovlev EG (Eksperimentalnyi Gelikopter), also commonly known as the Yak-M11FR-1 and Sh (Shootka), was an experimental aircraft with coaxial rotors. The prototype was first flown by V.V. Tezavrovsky in December 1947.

Design and development

The fuselage of the EG was a welded steel tube truss with duralumin skinning on the fwd fuselage back to the rear of the engine compartment. The rear fuselage was fabric covered and supported a tailplane-style unit with twin endplate fins, as well as a tailskid. The Pilot and Passenger sat side by side under a glazed canopy with a car-style door on each side.[1]

The M-11FR engine was mounted behind the gearbox which it drove via a short shaft. The gearbox supported the Rotor pylon which had two, contra-rotating, co-axial, two-bladed rotors. A fixed tricycle undercarriage mounted on steel tube trusses supported the helicopter on the ground.[1]

Flight testing revealed vibration at forward speeds above 20–30 km/h (12–19 mph; 11–16 kn) In an effort to reduce vibration the tailplane and fins were removed.[1]

In early 1948 the M-11FR engine was replaced by a 190 hp (140 kW) M-12, which proved troublesome so an M-11FR was refitted to complete the flight trials by 8 July 1948.[1]

Specifications

Data from OKB Yakovlev,[1] Yakovlev aircraft since 1924[2]

General characteristics

• Crew: 2
• Capacity: 142 kg (313 lb) payload
• Length: 6.53 m (21 ft 5 in) fuselage
• Empty weight: 878 kg (1,936 lb)
• Gross weight: 1,020 kg (2,249 lb)
• Fuel capacity: 50 kg (110 lb) fuel
• Powerplant: 1 × Shvetsov M-11FR-1 5-cylinder air-cooled radial piston engine, 100 kW (140 hp)
• Main rotor diameter: 2 × 10 m (32 ft 10 in)
• Main rotor area: 157.1 m^2 (1,691 sq ft) co-axial rotors

Performance

• Maximum speed: 150 km/h (93 mph, 81 kn) at sea level (design)
• Range: 235 km (146 mi, 127 nmi)
• Service ceiling: 2,700 m (8,900 ft) (design)
• Hover ceiling: 250 m (820 ft)
• Rate of climb: 3.1 m/s (610 ft/min)

See also

Related development

• Yakovlev Yak-100
• Mil Mi-1

References

1. Gordon, Yefim; Dmitry; Sergey Komissarov (2005). OKB Yakovlev. Hinkley: Midland Publishing. pp. 349-350. ISBN 1-85780-203-9.
2. Gordon, Yefim; Gunston, Bill (1997). Yakovlev aircraft since 1924 (1. publ. ed.). London: Putnam. pp. 123-126. ISBN 0851778720.

Further reading

• Gunston, Bill (1995). The Osprey Encyclopedia of Russian Aircraft 1875–1995. London: Osprey. p. 478. ISBN 1-85532-405-9.