Cunliffe-Owen OA-1

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Contents

Type Description

• OA-1
• High-wing semi-cantilever "flying wing" that incorporated an aerofoil-section body that enclosed and contained the 15 passenger rectangular planform cabin. The fuselage was an airfoil-section body in its own right having four main bulkheads, the first two carrying the loads of the two main spars and the outer-wing bracing struts. Number 3 bulkhead was open and served merely as a cabin stiffener, while the fourth bulkhead carried the load of the tail wheel. The whole fuselage had a stressed- skin covering of Alclad. Four passengers were seated facing aft behind No.1 bulkhead with five facing forward in front of No.2, and six facing forward in front of No.5 bulkhead, behind which was a large baggage compartment. Entry to the cabin was by a large door on each side. The two-crew cockpit was above and ahead of the cabin, in line with the leading edge of the wing. The tapered outer wings were of the same airfoil section and the centre body but of narrower chord were attached in such a manner that the upper surface of the wing extended from wing-tip to wing-tip without interruption. These outer wing panels were braced with parallel lift struts to the lower edges of the centre body. Structure of the wing comprised two ‘I’-sectioned spars, Warren girder ribs and a stressed metal skin of Alclad. There were narrow-chord ailerons over two-thirds of the outer wing span and split trailing edge flaps between ailerons and body. A further flap was located beneath the rear of the fuselage ahead of the tailwheel.
  The all-metal tailplane was carried on rectangular-section, wire cross-braced booms with ‘D’ shaped fairings above and below. These booms were attached to the rear of the main body as a continuation of the fuselage sides at a significant angle to the fuselage, being horizontal when the aircraft was on the ground. These booms differed significantly from the original Bumelli UB-14, being of much deeper section. The twin fins and rudders were at right angles to the boom, giving a very forward raked appearance in flight. The undercarriage was fully retractable, the two main wheels retracting forwards into the engine nacelles, located at the outboard corners of the fuselage body, while the fully-castoring tailwheel also retracted forwards into the tail end of the body. Retraction was by means of engine-driven hydraulics. Fuel was contained in eight tanks, four in each outer wing. The Rolls-Royce Kestrel powerplants of the proposed Scottish Aircraft and Engineering Companies Clyde Clipper were replaced by two Bristol Perseus sleeve-valve engines, originally intended to be 900 hp Perseus XIIC, but ultimately the 710 hp Bristol Perseus XIVC were installed, driving constant-speed fully-feathering three-bladed propellers.

Specification
Span	Length	Height	Wing Area	Empty Wt	Max AUW	Cruise Speed	Maximum Speed	Range	Service Ceiling
73 ft 4 in	45 ft 7 in	11 ft 3 in	826.5 sq ft	9500 lb	15000 lb	195 mph/ 169 kn	225 mph/ 196 kn	1950 mi
22.35 m	13.89 m	3.43 m	76.78 m2	4309 kg	6804 kg	314 kph	362 kph	3138 km

Projected Variants

• OA-1 Mk.II
• (Sometimes incorrectly referred to as the OA-2). A cleaned-up derivative of the OA-1, with improved nacelle lines and booms that were no longer canted upwards.

Production Details

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Production References

1. British Commercial Aircraft 1920-1940, Arthur W.J.G. Ord-Hume (GMS Enterprises, 2003)
2. Air Britain Archive 2008/2 (Air-Britain Publications)
3. https://www.secretprojects.co.uk/threads/cunliffe-owen-o-a-2-aircraft-the-companys-projects.4178/