<p>The improved financial stability that the Model 10 Electra had conferred upon Lockheed enabled the company to embark upon a new project in 1935. This evolved as another twin-engined design, outwardly similar to the Electra but of slightly smaller dimensions. Identified as the Model 12, it was one of the first aircraft intended for business use, seating six passengers in a well-furnished cabin.
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<p>From the start, the company was committed to a first flight target date of 27 June 1936, to enable the type to compete in the 1936 Department of Commerce design competition. That target was achieved, test pilot Marshall Headle taking off at 1212 on 27 June, and the aircraft subsequently won the competition. The Electra's Pratt & Whitney Wasp Juniors were retained, endowing the Model 12-A with a maximum speed of 240 mph (386 km/h), an improvement of 30 mph (48 km/h) compared with the performance of the earlier model. The 12-A was certificated on 14 October 1936, finding a ready market with both corporate and private owners, and with the airlines; 114 had been built when production ceased in 1942.
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<p>In 1937-38 the US services acquired Lockheed 12-As for transport duties, initially in seven-seat configuration. The US Navy took a single JO-1 and two JO-2s, three additional examples of the latter serving with the US Marine Corps. Three for the US Army Air Corps were designated C-40 and 10 five-passenger machines were known as C-40As. Impressed civil aircraft taken on charge in 1942 became UC-40Ds. The US Navy and US Air Corps each operated a single 12-A trainer with fixed tricycle-type landing gear, designated respectively XJO-3 and C-40B.
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<p>An armed version evolved in 1938 and the prototype flew in the following February, featuring a 0.50-in (12.7-mm) machine gun in the nose, another in a dorsal turret, and with underfuselage racks for up to eight 250-lb (113-kg) bombs. Sixteen were ordered by the Royal Netherlands Indies Army's Air Division for crew training duties in support of the division's Martin 139 bombers, and to form a Java-based maritime patrol squadron. Thirteen Lockheed 12-A transports had also been ordered, and eight of these were still undelivered when the Dutch East Indies fell into Japanese hands. Together with four similarly undelivered aircraft intended for KNILM (Royal Dutch East Indies Airways), they were used instead by the Netherlands Military Flying School at Jackson, Mississippi.
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<hi style=hdr1>Specification</hi>
<list style=aflst>
<item><hi format=bold>Type:</hi> six/seven-seat commercial and military light transport, and gunnery trainer
<item><hi format=bold>Powerplant:</hi> two 450-hp (336-kW) Pratt & Whitney R-985-SB Wasp Junior radial piston engines
<item><hi format=bold>Performance:</hi> maximum speed 225 mph (362 km/h); cruising speed 212 mph (341 km/h); service ceiling 22,900 ft (6,980 m); range 800 miles (1,287 km)
<item><hi format=bold>Weights:</hi> empty 5,960 lb (2,703 kg); maximum take-off 9,200 lb (4,173 kg)
<item><hi format=bold>Dimensions:</hi> span 49 ft 6 in (15.09 m); length 36 ft 4 in (11.07 m); height 9 ft 9 in (2.97 m); wing area 352 sq ft (32.70 m<su>2</su>)
<item><hi format=bold>Armament (military trainer):</hi> two 0.50-in (12.7-mm) machine guns (one in nose and one in dorsal turret), plus up to 2,000 lb (907 kg) of bombs carried externally
