Lockheed Model 12 Electra Junior

https://en.wikipedia.org/wiki/Lockhe...Electra_Junior

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. Several were also used for testing new aviation
technologies.

After Lockheed had introduced its 10-passenger Model 10 Electra, the company
decided to develop a smaller version which would be better suited as a "feeder
airliner" or a corporate executive transport. At the same time, the U.S. Bureau
of Air Commerce had also sensed the need for a small feeder airliner and
announced a design competition for one. In order for a candidate to qualify for
the competition, a prototype had to fly by June 30, 1936.

Lockheed based its candidate, which it named 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 450 hp (340 kW) Pratt & Whitney
R-985 Wasp Junior SB radial engines as the main Electra version, the 10A. This
made it faster than the Electra, with a top speed of 225 mph (362 km/h) at 5,000
ft (1,500 m). Like the Electra, the Model 12 had an all-metal structure,
trailing-edge wing flaps, low-drag NACA engine cowlings, and two-bladed
controllable-pitch propellers (later changed to constant-speed propellers). It
also had the Electra's twin tail fins and rudders, which were becoming a
Lockheed trademark. The landing gear was a conventional tail-dragger
arrangement, with the main wheels retracting backwards into the engine nacelles;
as was often the case with retractable gear of the period, the wheel bottoms
were left exposed in case a wheels-up emergency landing was necessary.

The original Lockheed 12 version, with Wasp Junior engines, was the Model 12A.
Almost every Lockheed 12 built was a 12A or derived from the 12A. There was also
a Model 12B, using 440 hp (330 kW) Wright R-975-E3 Whirlwind radials, but only
two of this model were built. Although Lockheed had also announced a Model 12F,
powered by Wright R-760 Whirlwind seven-cylinder radials, and a Model 12M,
powered by 290 hp (220 kW) Menasco six-cylinder inline engines, neither of these
versions reached production.


Role
Civil and military utility aircraft

Manufacturer
Lockheed Corporation

First flight
June 27, 1936

Number built
130

Developed from
Lockheed Model 10 Electra

Even though the Lockheed 12 had won the government's feeder airliner
competition, the airlines mostly rejected it, and very few Lockheed 12s were
used as airliners. One notable airline user was the newly renamed Continental
Air Lines, which had a fleet of three Lockheed 12s that ran on its route between
Denver, Colorado and El Paso, Texas in the late 1930s. Another was British West
Indian Airways Ltd., which flew the Lockheed 12 on Caribbean routes in the
Lesser Antilles during the mid-1940s.

The Lockheed 12 proved much more popular as a transport for company executives
or government officials. Oil and steel companies were among the major users. 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.

Several Lockheed 12s were used as technology testbeds. The U.S. National
Advisory Committee for Aeronautics (NACA) bought two, adding a center vertical
fin to each of them to improve their stability. One of the NACA Lockheed 12s was
used to test "hot-wing" deicing technology, in which hot exhaust air from the
engines was ducted through the wing's leading edge to prevent ice accumulation.

Three other Lockheed 12s were used to test tricycle landing gear. These had
their normal landing gear replaced by a non-retracting version with a large
nosewheel and with the main wheels shifted further back on the engine nacelles.
(The tailwheel from the normal conventional gear was retained.) The gear was
non-retractable because there wasn't room within the structure to stow it in
retracted position. Streamlined fairings were placed on the gear to reduce
drag.One of the tricycle gear Lockheed 12s went to the U.S. Navy as the XJO-3
and performed carrier landing tests on the USS Lexington to study the
suitability of a twin-engined tricycle-gear aircraft for carrier operations.
Another went to the U.S. Army as the C-40B, and still another was retained by
Lockheed for its own testing; both of these were eventually converted back to
the normal landing gear configuration.

Specifications (Model 12A)

General characteristics
Crew: two, pilot and co-pilot
Capacity: six passengers
Length: 36 ft 4 in (11.07 m)
Wingspan: 49 ft 6 in (15.09 m)
Height: 9 ft 9 in (2.97 m)
Wing area: 352 ft² (32.7 m²)
Empty weight: 5,765 lb (2,615 kg)
Loaded weight: 8,650 lb (3,924 kg)
Max. takeoff weight: 9,200 lb (4,173 kg)
Powerplant: 2 × Pratt & Whitney R-985 Wasp Junior SB radial engines, 450 hp (336
kW) each
Propellers: Two-bladed Hamilton Standard controllable-pitch or constant-speed
propeller, 1 per engine Propeller diameter: 8.5 to 9 ft (2.6 to 2.75 m)


Performance
Maximum speed: 225 mph (362 km/h, 196 kn) at 5,000 feet (1,500 m)
Range: 800 mi (1,300 km, 700 nmi)
Service ceiling: 22,900 ft (6,980 m)
Rate of climb: 1,140 ft/min (427 m/min)
Wing loading: 25 lb/ft² (120 kg/m²)
Power/mass: 0.10 hp/lb (0.17 kW/kg)





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