The C-73 Designation for Boeing 247D airliners “drafted” into military service with the USAAF.
Original proposal of Boeing 247 with 14 seats and 700 hp P&W Hornet engines.
Twin engined civil transport airliner.
Initial production version
Powered by new 625 hp P&W Wasp, on special order for Deutsche Lufthansa in 1934.
This designation was given to the first Boeing 247 aircraft, it was used to test a number improvements, that were later incorporated into the Boeing 247D
Original one off was a race aircraft designed for the MacRobertson Air Race, use of Hamilton Standard variable pitch propellers allowed for a 7 mph (11 km/h) gain, the 247D configuration incorporated in production series bearing the same name.
Armed version, one exported to China, second used for trials.
10 passengers, baggage and 400 lb (181 kg) of mail
51 ft 7 in (15.72 m)
74 ft 1 in (22.58 m)
12 ft 1.75 in (3.7021 m)
836.13 sq ft (77.679 m2)
8,921 lb (4,046 kg)
Max take-off weight
13,650 lb (6,192 kg)
273 US gal (227 imp gal; 1,030 l)
2 × Pratt & Whitney R-1340 S1H1-G Wasp 9 cylinder air cooled radial piston engines,
500 hp (370 kW) each at 2,200 rpm at 8,000 ft (2,438 m)