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The Lockheed C-40 was the Army designation for the Lockheed 12 Electra Junior, and covered a mix of aircraft that had been purchased by the Air Corps and aircraft that were impressed during the Second World War.
The standard Lockheed 12 Electra Junior was a smaller version of the Lockheed 10 Electra, with the same basic layout. It had a low mounted tapered cantilevered wing, with twin Pratt & Whitney Wasp Jr engines, a crew of two and space for six passengers (down from ten on the Electra).
The Army Air Corps first tested the Model 12 prototype in 1936, but didn’t acquire any aircraft until 1938. The first aircraft were three C-40s, which had seven seats. The first of them was evaluated at Wright Field in the summer of 1938, after originally being built as a company demonstrator.
They were followed by ten C-40As, powered by the Pratt & Whitney R-985-17 engine, and with five seats.
The final aircraft ordered for the Air Corps was the sole C-40B, which had a fixed tricycle undercarriage for experimental use. This was delivered during 1939, and was used for trials for the following year, before being converted to C-40A standard in November 1940.
After the United States entered the Second World War eleven civilian Model 12-As were impressed, and became the UC-40D.
The C-40 was used as a general utility transport. The US Navy also operated a number of the type, where it was designated as the Lockheed JO.
Standard Electra Jr
Engines: Two Pratt & Whitney Junior SB
Power: 450hp at take off, 400hp at sea level
Crew: 2
Wing span: 49ft 6in
Length: 36ft 4in
Height: 9ft 9in
Empty weight: 5,765lb
Loaded weight: 8,400lb
Maximum weight: 8,650lb
Maximum speed: 225mph at 5,000ft
Cruising speed: 213mph
Service ceiling: 22,900ft
Normal range: 800 miles