Technical data
Type KhAI-4 'Iskra'
Function Experimental
Year 1934
Crew 2
Engines 1*100hp M-11
Length 4.2m
Height ?m
Wingspan 12.0m
Wing area 21.25m2
Empty weight 550kg
Loaded weight 850kg
Wing Load (kg/m2) 40
Power load (kg/hp) 8.5
Speed at 0m 180km/h
Landing Speed 100km/h
Range 600km
Flight Endurance 4h
Ceiling (reached) 600m
Ceiling (expected) 3250m
Payload
Fuel 120kg

KhAI-4 'Iskra' (Osoaviakhimovets Ukrainy) by P.G.Benning, A.A.Lazarev and A.A.Krol (KhAI)

34k drawing from "History of aircraft construction in the USSR", Vol.2 p.121

Light tailless pusher aircraft, powered by M-11 engine. Two-seater with enclosed cockpit was of wooden design. Conventional non-slatted ailerons covered outer 65% of the wing span, elevones - the rest. Wing endplates served as a tailplanes with rudders. KhAI-4 was the first in the USSR aircraft with tricycle landing gear, nosewheel was steerable.

Since aircraft was experimental, special attention was payed to main undercarriage. It had pneumatic wheels and hydraulically linked legs, capable to withstand serious shocks.

Aircraft was build in Summer 1934. Pilot B.N.Kudrin had serious complications while flying this unusual aircraft. First, KhAI-4 did not like to takeoff. Diving propeller momentum decreased the attack angle, while short lever of elevones made them inefficient. Only occasional bump on the runway made first flight possible. This happened on 180km/h run speed.

Handling of KhAI-4 was quite poor. Transversal reaction of the aircraft was delayed due to its large momentum. Endplates were out off propeller flow and proved to be very inefficient.

Large diving momentum from the high-placed propeller created serious climb problems. To compensate for this momentum, extensive deployment of elevones was needed. This in turn degraded wing lift - and aircraft started loosing altitude. Maximum obtained altitude was only 600m, reached with neutral stick position. Similar problems were with landing, w which could be performed only at small attack angle and high speed.

Undercarriage proved sturdy enough to withstand 'parachuting' from 1m altitude.

After third flight trial program was terminated: KhAI-4 was considered dangerous to fly. Nonetheless, ability of tailless aircraft to fly was proven, opening wide field of experimentation.


PredecessorsModifications
None Elements were used in KhAI-3 moto-glider

ReferencesLinks
  • "History of aircraft construction in the USSR", Vol.2 p.120-121;
  • KhAI-4 (Slovak)
  • Created September 2, 1999 Back to
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