The Menasco Unitwin 2-544 was a coupled piston engine. Menasco Motors Company of Burbank, California was a well known manufacturer of inverted inline four and six cylinder engines. At the request of Lockheed Aircraft 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.
In mid-1935 Lockheed's chief engineer, Hall Hibbard, began discussing with Al Menasco, the president of the Menasco Motors Company in Burbank, the merits of coupling two Menasco C6S Super Buccaneer six-cylinder in-line engines mounted side-by-side, driving a single propeller.[1]
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 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.[2]
During 1938 the AiRover Company was reorganized as the Vega Aircraft Corporation, 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.[3]
Operational historyedit
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 SC in 1939, and was then registered as a Lockheed Altair 8-D in 1940.[4]
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 Burbank, California 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.
Variantsedit
The Unitwin was developed in at least three versions:
Francillon, René J, Lockheed Aircraft since 1913. Naval Institute Press: Annapolis, 1987
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November 03, 2023
menasco, unitwin, this, article, uses, bare, urls, which, uninformative, vulnerable, link, please, consider, converting, them, full, citations, ensure, article, remains, verifiable, maintains, consistent, citation, style, several, templates, tools, available, . This article uses bare URLs which are uninformative and vulnerable to link rot Please consider converting them to full citations to ensure the article remains verifiable and maintains a consistent citation style Several templates and tools are available to assist in formatting such as reFill documentation and Citation bot documentation August 2022 Learn how and when to remove this template message The Menasco Unitwin 2 544 was a coupled piston engine Menasco Motors Company of Burbank California was a well known manufacturer of inverted inline four and six cylinder engines At the request of Lockheed Aircraft 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 Unitwin 2 544TypeNational origin United StatesManufacturer Menasco Motors CompanyFirst run 1938Major applications Vega Altair 8G Vega Model 2 StarlinerDeveloped from Menasco C6S Super Buccaneer Contents 1 Design and development 2 Operational history 3 Variants 4 Applications 5 Specifications U 2 544 5 1 General characteristics 5 2 Components 5 3 Performance 6 See also 7 ReferencesDesign and development editIn mid 1935 Lockheed s chief engineer Hall Hibbard began discussing with Al Menasco the president of the Menasco Motors Company in Burbank the merits of coupling two Menasco C6S Super Buccaneer six cylinder in line engines mounted side by side driving a single propeller 1 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 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 2 During 1938 the AiRover Company was reorganized as the Vega Aircraft Corporation 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 3 Operational history editThe 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 amp Whitney Wasp SC in 1939 and was then registered as a Lockheed Altair 8 D in 1940 4 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 Burbank California 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 editThe 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 22None of these engines survivedApplications editVega Altair 8G Vega Model 2 StarlinerSpecifications U 2 544 editData from Peter and Rita Ford 5 General characteristics Type 12 cylinder inline inverted U Bore 4 75 in 121 mm Stroke 5 125 in 130 2 mm Displacement 1088 cu in Length 87 125 in Width 34 625 in Height 31 50 in Dry weight 1 350 lb 610 kg Components Valvetrain Pushrod overhead valve 1 intake 1 exhaust Supercharger 10 90 1 Fuel type 87 octane aviation gasoline Cooling system Air cooled Reduction gear Direct drive 4 X Scintilla MagnetosPerformance Power output 520 hp 390 kW Compression ratio 5 50 1 Power to weight ratio 3 00 lb hp 147 bmep at cruise 450 hp at 2400 rpm and 5400 feet altitude See also editRelated development Menasco BuccaneerReferences edit nbsp Wikimedia Commons has media related to Menasco Unitwin Tinkering Around Collections Autry National Center Archived from the original on 2013 04 15 Retrieved 2012 01 04 Francillon http www pilotfriend com acft manu Lockheed 20Martin htm aircraftone com Peter amp Rita Forbes Engine Webpages Francillon Rene J Lockheed Aircraft since 1913 Naval Institute Press Annapolis 1987 Peter amp Rita Forbes Engine Webpages aircraftone com 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