The Menasco Unitwin 2-544 was a coupled

piston engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...

Menasco Motors Company The Menasco Motors Company was an American aircraft engine and component manufacturer. History The company was organized by Albert S. Menasco in 1926 to convert World War I surplus Salmson 9 (water-cooled engine), Salmson Z-9 water-cooled nine ...

Burbank, California Burbank is a city in the southeastern end of the San Fernando Valley in Los Angeles County, California, United States. Located northwest of downtown Los Angeles, Burbank has a population of 107,337. The city was named after David Burbank, w ...

was a well known manufacturer of inverted inline four and six cylinder engines. At the request of

Lockheed Aircraft Lockheed (originally spelled Loughead) may refer to: Brands and enterprises * Lockheed Corporation, a former American aircraft manufacturer * Lockheed Martin, formed in 1995 by the merger of Lockheed Corporation and Martin Marietta ** Lockheed Ma ...

designers, Menasco produced an inverted twelve-cylinder air cooled aircraft engine by designing a common crankcase and gearbox for two of the six cylinder engines. The two crankshafts were combined with a unique double clutch gearbox to power a single propeller. This gave reliability of a twin engine aircraft in a single powerplant. It was a success, but did not enter production as no aircraft were produced that used it.

Design and development

In mid-1935 Lockheed's chief engineer,

Hall Hibbard Hall Livingstone Hibbard (July 26, 1903 – June 6, 1996) was an engineer and administrator of the Lockheed Corporation beginning with the company's purchase by a board of investors led by Robert E. Gross in 1932. Born in Kansas, he received a bach ...

, began discussing with

Al Menasco AL, Al, Ål or al may stand for: Arts and entertainment Fictional characters * Al (''Aladdin'') or Aladdin, the main character in Disney's ''Aladdin'' media * Al (''EastEnders''), a minor character in the British soap opera * Al (''Fullmetal ...

, the president of the Menasco Motors Company in Burbank, the merits of coupling two

Menasco C6S The Menasco Buccaneer was a series of popular six-cylinder, air-cooled, in-line, inverted, aero-engines, that were manufactured by Menasco Motors Company for light general aviation and sport aircraft during the 1930s and 1940s. The six-cylinde ...

Super Buccaneer six-cylinder in-line engines mounted side-by-side, driving a single propeller. In 1937 Lockheed established the AiRover Aircraft Company as a subsidiary to give Lockheed a place in the personal aviation market. Hall Hibbard wanted AiRover to use Menasco's novel twin powerplant in its first aircraft. AirRover used components of various Lockheed aircraft to construct what was designated as the

Lockheed Altair The Lockheed Altair was a single-engined sport aircraft produced by Lockheed Aircraft Limited in the 1930s. It was a development of the Lockheed Sirius with a retractable undercarriage, and was the first Lockheed aircraft and one of the first air ...

8G to serve as a flying test stand for the unproven Menasco engine. This test bed was first flown in December 1937 and confirmed the merits of its powerplant, leading to the decision to proceed with the design of a similarly-powered five-seat feeder-liner. During 1938 the AiRover Company was reorganized as the

Vega Aircraft Corporation The Vega Aircraft Corporation was a subsidiary of the Lockheed Aircraft Company in Burbank, California responsible for much of its parent company's production in World War II. History The company was first formed in August 1937 as the AiRover ...

, and with Mac V.F. Shortits installed as president, it started the design the new feeder-liner. Jack Wassail was the project engineer, and the aircraft was soon under construction in Vega's new A-1 plant, located at the recently purchased

Lockheed Air Terminal Lockheed (originally spelled Loughead) may refer to: Brands and enterprises * Lockheed Corporation, a former American aircraft manufacturer * Lockheed Martin, formed in 1995 by the merger of Lockheed Corporation and Martin Marietta ** Lockheed Mar ...

Operational history

The "Flying Testbed" was a custom built Vega Altair 8 (NX18149) used to test the experimental 520 hp Menasco Unitwin for use in the planned Starliner. The engine was two 260 hp Menasco C6S-4 Super Buccaneer engines mounted to a common gearbox that drove a single, two-blade, variable-pitch propeller. When it was no longer needed, the airplane was sold to Howard Batt, a Lockheed dealer. It was reengined with a 450 hp

Pratt & Whitney Wasp The Pratt & Whitney Wasp was the civilian name of a family of air-cooled radial piston engines developed in the 1930s, 1940s, and 1950s.Gunston 1989, p.114. The Pratt & Whitney Aircraft Company (P&W) was founded in 1925 by Frederick B. Rentsch ...

SC in 1939, and was then registered as a Lockheed Altair 8-D in 1940.aircraftone.com Starliner Model 2, registered NX21725, rolled out of the factory in the spring of 1939 as a low-wing cabin monoplane with twin vertical tail surfaces. Its tricycle undercarriage retracted aft, with the wheels partially protruding beneath the nose and wing. The Starliner was the first totally new Vega Airplane Company aircraft. It made its maiden flight at

on April 22, 1939, with Vern Dorrell as pilot and J.B. Kendrick as engineering observer. The flight ended with an emergency when the propeller accidentally slipped into fine pitch. Vern Dorrell succeeded in landing on a vacant field, with minimum damage to the aircraft. During repairs the twin tail was changed to a single vertical tail surface and an upgraded 640 hp Unitwin engine, the Starliner model 2 became the model 22 when it resumed its test flights. The Starliner was damaged again when Bud Martin had to land it on its main wheels when the nose wheel failed to come down. With the nose protected by the partially protruding front wheel, the aircraft again escaped with only slight damage to its lower cowling. Repaired a second time, the Starliner satisfactorily completed a total of 85 flying hours; but due to its limited capacity of a pilot and four or five passengers, it was too small to satisfy the needs of the airlines. Menasco and Vega were increasingly occupied with military contracts. The only Starliner ended its life as a non-flying prop at a film studio.

Variants

The Unitwin was developed in at least three versions: ;520 hp Unitwin : Original version ;600 hp Unitwin : for the Starliner model 2 ;640 hp Unitwin : for the Starliner model 22 None of these engines survived

Applications

* Vega Altair 8G *

Vega Model 2 Starliner The Vega Model 2 Starliner was a prototype five-seat feeder airliner produced by the Vega Airplane Company, a subsidiary of Lockheed. It was designed to be powered by an unusual powerplant, consisting of two Menasco piston engines coupled toget ...

Specifications (U 2-544)

References