Crawford monoplane
Страна: Великобритания
Год: 1925

Aeroplane Monthly, May 1978

Aeroplane Monthly, May 1978

Obviously inspired by the de Havilland D.H.53 of 1923, yet differing from it in almost every detail, this early ultralight aircraft was designed in 1924 by Flt Lt Crawford, then stationed at the Iraq Aircraft Depot, RAF Hinaidi, and built as a leisure occupation in off-duty hours. He was assisted in its construction by carpenter-rigger Cpl Howden and armourer LAC Farmer, who built the fuselage in the form of a Charles Sims
conventional Warren girder with spruce longerons, vertical and diagonal struts, fabric-covered except forward from the cockpit area, which had plywood-covered bottom and sides with aluminium top-decking. The undercarriage was a simple vee frame carrying two hollow wooden wheels on a bungee-sprung axle.
   The two-spar mainplane was of RAF 15 section, tapered at the root ends as on the D.H.53, but was braced to the top longerons by parallel instead of converging streamlined steel struts. Tailplane incidence was ground-adjustable and the absence of a fin ahead of the comma-shaped rudder was more reminiscent of the Avro Baby. The whole aeroplane was, in fact, smaller and lighter than the 53, having 2ft less span, a 3ft 5in shorter fuselage, and 130lb less all-up weight than the RAF’s Blackburne Tomtit-engined machines.
   The only available power plant at Hinaidi was a 500cc air-cooled, two-cylinder A.B.C. engine lying unused after long service on an electricity generating set. Two 7/16 in steel bolts clamped it direct to the 1/2 in seven-ply engine bulkhead, and the front end of the crankcase was braced to the bottom longerons by two 3/4 in tubular steel struts. Petrol was gravity fed from a one gallon brass tank in front of the cockpit and lubrication was via an engine-driven pump from an oil tank bolted to the crankcase.
   Trials began on December 11, 1924, the day the aircraft was completed, but despite good elevator and aileron response, the maximum tail-up speed of 30 m.p.h. was insufficient for it to unstick. The team then experimented with pitch changes to the gear driven wooden propeller, and with improvements to the carburation, but in January 1925, after all attempts to get airborne had failed, an entirely new engine was designed. This was built from parts of two other time-expired 500cc A.B.C. generator engines, the two crankcases, after careful machining, being combined to form a single, four-cylinder, horizontally opposed power unit with coupled camshafts and crankshafts, the latter driving a single magneto through chain and sprocket gear. A specially designed hub and thrust race for the propeller shaft were manufactured.
   It is great testimony to the skill of these dedicated experimenters that such an engine ran successfully right from the start, and with 1,000cc “up front” the Crawford monoplane at last left the ground in February 1925, piloted by the designer and later by Flt Lts Ashton and Dixon of the Depot staff. It handled well in the air and on March 4, 1925, Flg Off Attwood flew a circuit of Hinaidi Aerodrome.
   Crawford's monoplane was finished in RAF silver with roundels and rudder flashes but, being a private venture, was ineligible for an RAF serial. Nor were civil marks applied for, because registration for machines flown on test within three miles of an aerodrome were not mandatory in those days. In 1926, when Flt Lt Crawford was posted home to serve with Group Headquarters, Lee-on-Solent, the monoplane went with him but did not fly again and was up for sale in 1927. As nothing more was heard of it, it must be assumed to have been scrapped.

View of the Crawford monoplane at Hinaidi in December 1924, with the original 500cc two-cylinder ABC engine.
The view shows the Avro-like tail unit, parallel strutting, Flt Lt Crawford, and three D.H.9As on major overhaul in the hangar.
Crawford light aeroplane