Lockheed 12A (Electra Junior)

The US Army Air Corps acquired three seven-seat C-40 (later UC-40), 10 five-seat C-40A (later UC-40A) and one experimental C-40B aircraft with fixed tricycle landing gear; the designation C-40D (later UC-40D) was allocated to 10 Lockheed 12-As impressed for wartime service. The US Navy received one seven-seat JO-1, five six-seat JO-2 aircraft (one of which was allocated for US Marine Corps use), and a single XJO-3 with fixed tricycle landing gear which was used for carrier deck-landing trials. The type was used also by the air arms of Argentina, Canada, Cuba and the UK, as well as by the Netherlands East Indies army, this last service being the major military user with a total of 36. Of this number, 16 were specially-developed Model 212 crew trainers, with a forward-firing 7.7mm machine-gun, a similar weapon in a dorsal turret, and under fuselage racks for up to 363kg of bombs.
 

The Lockheed Model 12 Electra Junior, more commonly known as the Lockheed 12 or L-12, is an eight-seat, six-passenger all-metal twin-engine transport aircraft of the late 1930s designed for use by small airlines, companies, and wealthy private individuals. A scaled-down version of the Lockheed Model 10 Electra, the Lockheed 12 was not popular as an airliner but was widely used as a corporate and government transport. Lockheed based the Model 12 Electra Junior, around a smaller, improved version of the Electra airframe. It would carry only six passengers and two pilots but would use the same Pratt & Whitney R-985 Wasp Junior SB radial engines as the main Electra version (the 10A). This made it faster than the Electra.
Military models: All of these were based on the Model 12A and used the same engines. C-40: U.S. Army Air Corps five-passenger transport; three built, redesignated UC-40 in January 1943 C-40A: U.S. Army Air Corps transport with mixed passenger/cargo interior; 10 built, plus one converted from C-40B, redesignated UC-40A in January 1943 C-40B: U.S. Army Air Corps test-bed for testing fixed tricycle landing gear; one built, converted to a normal C-40A in 1940 C-40D: Eleven civil Model 12As impressed by the U.S. Army Air Forces in 1942, with standard six-passenger interior. Redesignated UC-40D in January 1943 JO-1: U.S. Navy five-passenger transport JO-2: U.S. Navy and Marine Corps six-passenger transport XJO-3: U.S. Navy test-bed with fixed tricycle gear, used for carrier landing tests and airborne radar trials R3O-2: Civil Model 12A impressed by the U.S. Navy in 1941 Model 212: Bomber trainer with bomb racks and gun turret atop aft fuselage; built for the Royal Netherlands East Indies Army Air Force Model 12-26: Military transport version of the Model 212

One of the most interesting aircraft was that acquired by NACA, predecessor of NASA, which was used to evaluate a wing de-icing system that utilized hot gases from the engine exhaust. One of the most unusual applications of the Lockheed 12-A was by Australian Sidney Cotton who, under the cover of his position as an executive of the Dufaycolour Company, used his specially modified camera-carrying Lockheed 12-A to take clandestine reconnaissance photographs of German military installations in the three months leading up to the beginning of World War II.

A number were purchased as military staff transports by the United States Army Air Corps, which designated the type as the C-40, and by the United States Navy, which used the designation JO, or in one peculiar case, R3O-2. With the arrival of World War II, many civilian Lockheed 12s were requisitioned by the U.S. Army and Navy, Britain's Royal Air Force, and the Royal Canadian Air Force.
Two civil Lockheed 12s ordered by British Airways Ltd. were actually intended for covert military espionage. Sidney Cotton modified these aircraft for aerial photography and, while pretending to conduct ordinary civil flights, used them to overfly and photograph many German and Italian military installations during the months preceding World War II.