- 29 April 2007
- Reaction score
Airspeed AS.31 aka Airspeed F.35/35. Does anybody know more about it?
"Airspeed Aircraft since 1931" by H.A. Taylor, Putnam, 1970, p.155.AS.31
Rarely has there been such a strange and ingeniously original aircraft project as the AS.31 fighter. This was a tractor monoplane, powered by an 880 hp Rolls-Royce Merlin E twelve-cylinder vee liquid-cooled engine, in which the tailplane, on twin tubular metal booms, carried the pilot in an egg-shaped streamlined nacelle. It was designed to meet Air Ministry specification F.35/35 and was the subject of Patent No. 470650 in the names of Airspeed and A.H. Tiltman. Amongst the advantages claimed for military purposes were a reduction in slipstream disturbance and drag in the area immediately behind the engine and propeller; a reduction in skin friction; and good fighting and flying view provided for the pilot, though this might in practice have been marginal in some circumstances.
Among the features of the AS.31 were a wide-track retractable main undercarriage (unusual still in 1936-era British military aircraft), a tailwheel retracting into the rear part of the pilot's nacelle, and the burying of fuel, oil, armament, coolant-radiators and such items as oxygen bottles in the thick-section cantilever wing. Eight Browning guns were to be buried in the outboard of the booms. Split flaps were fitted across the trailing edge of the wing between the booms, with wide-span ailerons outboard.
Curiously, no rudder or fin surface (apart from the nacelle itself) are indicated in the original prints from which the general arrangement, reproduced here, was developed. In level flight, the pilot's view, with his seat fully raised, was unrestricted above the wing and engine, and was restricted by little more than 9 degrees downwards on either side of the engine-nacelle cowling. With the seat in the lowest position the pilot's view under the wing and flap would probably have been adequate in the fully-flared tail-down attitude but questionable during the final approach and hold-off.
Span 33 ft (10.06 m); length 29 ft 6 in (8.99 m); wing area 195 sq ft (18.1 sq m).
"The British Aircraft Specification File" by KJ Meekcoms & EB Morgan, Air-Britain, 1994, p.217.35/35
High Speed Aircraft (Experimental)
See aircraft types below
File no. 460005/35/RDA.3 (S.36972)
Issued to Tender 7/12/35
This specification, in satisfying Operational Requirement OR.30, included the following statement:- "Since the time of the Schneider Trophy Race the problem of producing an aircraft in which all other qualities are sometimes sacrificed for speed has always been a matter of great importance." It appears that an aircraft armament of eight forward-firing machine guns may have also been a specification requirement.
Four firms responded with project designs to Specification 35/35. The best recorded design is that for the Airspeed AS.31.
The Airspeed A.S.31 was a tractor monoplane in which the tailplane, on twin metal booms, carried the pilot in an egg-shaped nacelle. No rudder or fin surface was indicated on the general arrangement drawing. Split flaps were fitted on the trailing edge of the wing between the booms, with wide-span ailerons outboard of the booms. A wide-track undercarriage was depicted. The aircraft was powered by a Rolls-Royce Merlin E engine. No details of its potential performance are recorded. Its wing span was 33 ft. and its length 29.5 ft.
The Bristol 151 project design is recorde as a high-speed single-seat monoplane, powered by a Bristol Hercules engine. Its speed, with 100 octane fuel, was estimated to be 440 mph.
The General Aircraft GAL.28 design was a single-seat high speed fighter project, powered by a single Hercules engine, with a wing of variable area.
The Hawker design was a Hurricane variant, with its engine coolant radiator duct in line with the leading edge of the mainplane, was recorded as being tendered on 21/2/36/.
-- Specification not proceeded with --
I don't know why the Putnam and others say that the AS31 was to be powered by a Merlin E, the drawings in the patent and company artwork clearly show four exhaust pipes for four banks of cylinders, so most likely intended to be powered by a Vulture. This make sense for an aircraft intended for high speed research