De Havilland DH 91 Albatross
Designed by A. E. Hagg to an Air Ministry specification for a transatlantic mailplane, the de Havilland D.H.91 Albatross fuselage was made of laminations of cedar ply and balsa wood, built as a monocoque in which the skins bore the load, and had a one-piece wing.
Powered of four de Havilland Gipsy Twelve engines driving constant-speed propellers, and with the landing gear main units electrically retractable, the prototype, initially with twin fins mounted at mid-span on the tailplane, was flown for the first time at Hatfield on 20 May 1937. Directional instability saw a change to more traditional endplate fins with unbalanced rudders and trim tabs. Passenger entry was through a door just 1m tall and the rear fuselage was particularly cramped. In general the cabin was noisy and the ride was uncomfortable.
Problems with the landing gear retraction system resulted in a wheels-up landing for the first prototype on 31 March 1938, and a structural weakness in the rear fuselage was revealed when the second prototype broke into two a few months later when landing during overload trials. Effective modifications were soon evolved and the two prototypes were repaired and used experimentally by Imperial Airways.
Their range made them particularly useful for a shuttle service between the UK and Iceland, and they were impressed for RAF use with No. 271 Squadron in September 1940.
Five Albatrosses, with reduced capacity, additional cabin windows and slotted flaps replacing the split trailing edge flaps, were delivered to Imperial Airways between October 1938 and June 1939. With accommodation for 22 passengers and a crew of four, they saw wartime service on the Bristol-Lisbon and Bristol-Shannon routes until, with their numbers reduced to two by enemy action or accidents, the survivors were scrapped in September 1943.
Engines: 4 x de Havilland Gipsy Twelve, 391kW/ 525 hp
Max take-off weight: 13381 kg / 29500 lb
Empty weight: 9630 kg / 21231 lb
Wingspan: 32.00 m / 105 ft 0 in
Length: 21.79 m / 71 ft 6 in
Height: 6.78 m / 22 ft 3 in
Wing area: 100.15 sq.m / 1078.00 sq ft
Wing loading: 27.47 lb/sq.ft / 134.00 kg/sq.m
Max. speed: 362 km/h / 225 mph
Cruise speed: 338 km/h / 210 mph
Ceiling: 5455 m / 17900 ft
Max range: 3,300 miles (5,300 km)
Range: 1674 km / 1040 miles