Menasco Unitwin 2-544

Menasco Unitwin 2-544
Type
National origin	USA
Manufacturer	Menasco Motors Company
First run	1938
Major applications	Vega Altair 8G and Vega Starliner 2 and 22
Developed from	C6S Super Buccaneer

Design and development

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.

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.

During 1938 the AiRover Company was reorganized as the Vega Airplane Company, 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.

Applications

The Starliner model 2, with registration NX21725, rolled out of the factory in the spring of 1939 as a low-wing cabin monoplane with conventional tail surfaces. Its tricycle undercarriage retracted aft, with the wheels partially protruding beneath the nose and wing.

The powerplant was the 520 hp Menasco Unitwin, which was two 260 hp Menasco C6S-4 Super Bucaneer engines mounted to a common gearbox that drove a single, two-blade, variable-pitch propeller. This arrangement provided twin-engined reliability in a single-engined configuration as power would continue to be delivered to the propeller via clutches in the gearbox in the event one of the engines failed in-flight.

The Starliner was the first totally new Vega Airplane Company aircraft. It made its maiden flight at Burbank on April 22, 1939, with Vern Dorrell as pilot and J.B. Kendrick as engineering observer. This first flight, however, ended with an emergency when the propeller accidently slipped into fine pitch. Vern Dorrell succeeded in landing on a vacant field, with minimum damage to the aircraft.

Once repaired, and modified with twin vertical tail surfaces 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. The only Starliner ended its life as a non-flying machine with a film studio.

Variants

The Unitwin was developed in at least three versions:

520hp Unitwin Original version

600hp Unitwin for the Starliner model 2

640hp Unitwin for the Starliner model 22

-- Survivors --

Although none are flying, a number of Menasco Unitwin engine are in Museums.

References

[[Category:]]

Indented line

520hp Menasco U-520 Unitwin (twin 260hp Super Buccaneers with a gearbox driving a single propeller); 600hp Menasco U-600 Unitwin 640hp Menasco U-640 Unitwin

Starliner 2 600hp Menasco Unitwin Starliner 22 640hp Menasco Unitwin 2-544

http://aerofiles.com/_uv.html

Vega Flying Test Stand [NX18149] (WASM)

Flying Test Stand 1938 (ATC 2-423) = 2pOlwM rg; 520hp Menasco U-520 Unitwin (twin 260hp Super B with single propeller); span: 42'9" length: 28'11". Jack Wassall, W N "Wally" Wallace. Assembled from various Lockheed components, first designated Lockheed Altair 8-G. POP: 1 [NX18149] used to test experimental Unitwin for use in planned Starliner. Sold to Lockheed dealer Howard Batt when it was no longer needed, repowered with 450hp P&W Wasp SC under (2-423) in 1939 and reregistered as Lockheed Altair 8-D in 1940.

Vega Starliner [NX21725] (Lockheed)

Starliner 2, 22 1939 = 6pClwM rg; 600hp Menasco Unitwin; span: 41'0" (?>45'0") length: 31'6" (?>35'1") load: 1660# v: 195/180/60 (?>210/200/60) range: 600 (?>700); ff: 4/22/39 (p: B A Martin). Semi-monocoque fuselage, twin tail. POP: 1 [NX21725]. 22 was a modification with 640hp Menasco Unitwin 2-544 and a single tail. Production canceled by outbreak of WW2; aircraft sold to a film studio and its track faded.

http://1000aircraftphotos.com/Contributions/Larkins/10417.htm

01/31/2011. In mid-1935 Lockheed's chief engineer, Hall Hibbard, began discussing with Al Menasco, the president of the Menasco Manufacturing Company in Burbank, the merits of coupling two Menasco six-cylinder in-line engines, mounted side-by-side and driving a single propeller. As this arrangement provided twin-engined reliability in a single-engined configuration, Lockheed decided two years later to use the novel powerplant in an aircraft to be designed by its new subsidiary, the AiRover Company.

Moreover, before proceeding with the design, Lockheed asked AiRover to assemble from available components an Altair 8G intended to serve as a flying teststand for the twin Menasco engine. This test bed was first flown in December 1937 and soon confirmed the merits of its powerplant, thus leading to the decision to proceed with the design of a similarly-powered five-seat feeder-liner.

During 1938, by which time the AiRover Company had been reorganized as the Vega Airplane Company, its president, Mac V.F. Short, undertook to design the new feeder-liner. With Jack Wassail as project engineer, the aircraft was built in the new plant A-1 and emerged in the spring of 1939 as a low-wing cabin monoplane with conventional tail surfaces. Its tricycle undercarriage retracted aft, with the wheels partially protruding beneath the nose and wing. The powerplant, known as the Unitwin, consisted of two 260 hp Menasco C6S-4 engines driving a single, two-blade, variable-pitch propeller.

http://www.pilotfriend.com/acft_manu/Lockheed%20Martin.htm In 1937 Lockheed established a new AiRover Aircraft subsidiary to give Lockheed a place in the personal aviation market. Ai developed the StarLiner business airplane, but it didn't sell in the depressed market. AiRover became Vega Airplane Company in June 1938, which converted to military activity when the war began. At the end of 1941, Vega Airplane became Vega Aircraft Corporation, and Lockheed absorbed it on November 30, 1943. Its plants at Burbank, California, built more than 2,500 Boeing B-17s under license and also the PB-1 patrol bomber.

Named the Starliner and bearing the experimental registration NX21725, the first totally new aircraft of the Vega Airplane Company made its maiden flight at Burbank on April 22, 1939, with Vern Dorrell as pilot and J.B. Kendrick as engineering observer. This first flight, however, ended with an emergency when the propeller accidently slipped into fine pitch. Vern Dorrell succeeded in landing on a vacant field, with minimum damage to the aircraft.

Soon repaired, and fitted at that time with twin vertical tail surfaces, the Starliner resumed its trials but was damaged again when Bud Martin had to land it on its mainwheels when the nosewheel 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.

Once more repaired, the Starliner satisfactorily completed a total of 85 flying hours; but its limited capacity, pilot and four or five passengers, was found to be too small to satisfy the needs of the airlines. Moreover, by then Lockheed needed Vega Airplane Corporation's factory for military aircraft production, and development of the Starliner was discontinued. It ended its life as a non-flying machine with a film studio.

Span: 41 ft 0 in (12.5 m) Length: 32 ft 5 in (9.88 m) Height: 8 ft 6 in (2.59 m) Empty weight: 4,190 lb (1,901 kg) Loaded weight: 6,000 lb (2,722 kg) Max speed: 210 mph (338 kmh) at 7,500 ft (2,285 m) Cruise speed: 178 mph (286 kmh) Climb: 1,350 ft (411 m)/min Service ceiling: 21,500 ft (6,555 m) Range: 640 mls (1,030 km)

http://www.oldengine.org/members/diesel/duxford/usaero8.htm http://www.oldengine.org/members/diesel/duxford/usaero9.htm

Menasco Engine Data Sheets

Maker Menasco Pirate C4 Menasco Pirate C4S Menasco Buccaneer B6 Menasco Buccaneer B6S Menasco Super Buccaneer C6S-4 Menasco Unitwin 2-544

Arrangement Inverted In-Line Inverted In-Line Inverted In-Line Inverted In-Line Inverted In-Line Inverted In-Line

Cooling Air Air Air Air Air Air

No of Cyls 4 4 6 6 6 12

Bore/Stroke 4.75"/5.125" 4.75"/5.125" 4.50"/5.125" 4.50"/5.125" 4.75"/5.125" 4.75"/5.125"

Displacement 363 cu ins 363 cu ins 489 cu ins 489 cu ins 544 cu ins 1088 cu ins

Comp Ratio 5.50:1 5.50:1 5.50:1 5.50:1 5.50:1 5.50:1

bmep Cruise 105 121 108 121 132 147

Blower ratio N/A 9.60:1 N/A 8.75:1 10.90:1 10.90:1

Cyl Material Steel Steel Steel Steel Steel Steel

Valves per cyl 1 Inl 1 Exh 1 Inl 1 Exh 1 Inl 1 Exh 1 Inl 1 Exh 1 Inl 1 Exh 1 Inl 1 Exh

Valve Arr. OHV OHV OHV OHV OHV OHV

HP max - not Take-Off 125 150 160 200 260 600

@ RPM 2175 2260 1975 2250 2300 2400

@ Altitude Sea Level 3000ft Sea Level 4500ft 7500ft 5400ft

HP Take-Off 125 158 160 212 290 660

@ RPM 2175 2250 1975 2250 2400 2480

HP Cruise 95 112 120 150 195 450

@ RPM 1975 2025 1800 2025 2150 2230

Fuel Octane 73 73 73 73 87 87

Prop Drive Direct Direct Direct Direct Direct Direct

Dry Weight 284lbs 299lbs 398lbs 423lbs 550lbs 1350lbs

lb/Cruise HP 2.99 2.67 3.32 2.82 2.82 3.00

Carb(s) 1x Stromberg 1x Stromberg 1x Stromberg 1x Stromberg 1x Stromberg 1x Stromberg

Ignition Bendix Mag Bendix Mag Bosch Mag(2) Bosch Mag(2) Scintilla Mag(2) Scintilla Mag(4)

Electric Starter Eclipse Eclipse N/A N/A Eclipse Eclipse

Length 47.531" 47.531" 59.437" 60.125" 67.469" 87.125"

Height/O.D. 28.562" 28.562" 28.312" 28.312" 30.594" 31.50"

Width 17.781" 14.50" 11.875" 14.906" 16.562" 34.625"

Mount Dia 16.625" 16.625" 11.875" 11.875" 13.50" 30"

Designed by Lockheed's subsidiary AiRover Company, which by 1938 became the Vega Airplane Company, the Vega Starliner was a five/six-seat low-wing cabin monoplane with retractable landing gear and an unusual powerplant. This comprised two Menasco C6S-4 inline engines (the 640hp Menasco Unitwin 2-544), mounted side-by-side driving a common gearbox for a single propeller. They could operate independently in an emergency. It was built with both a twin-fin/rudder and the single arrangement shown here (the Starliner 22).

First flown on 22 April 1939, The resulting Starliner had a mixed construction airframe with a typical Lockheed tapered wing with split flaps, a side-door cabin a pilot and five passengers. In 1940 the project was abandoned after some 85 flight test hours, the Starliner was too small to appeal to the airlines, and too large for most private customers. The aircraft ended its days in film studios, fate unknown.

The Vega Aircraft Corporation was a subsidiary of the Lockheed Aircraft Company responsible for much of its parent company's production in World War II. The company was first formed in August 1937 as the AiRover Company to produce a new lightplane design. It was soon renamed to honor Lockheed's first aircraft design.

http://www.pprune.org/aviation-history-nostalgia/332082-silhouette-challenge-569.html#post5812010 The AiRover Model 1 was an Orion fitted with a Unitwin engine, which featured two engines driving a single shaft. The AiRover Model 2 was a new design named the Starliner. One Starliner prototype was built and tested, but the design did not go into production. http://www.aircraftone.com/aircraft/engines/engines3.asp MENASCO 0-45 Reciprocating 22 0 5

MENASCO A-6 Reciprocating 140 0 0

MENASCO B6S Reciprocating 200 0 0

MENASCO BUCCANEER B-6 Reciprocating 160 0 0

MENASCO BUCCANEER B6S Reciprocating 200 0 1

MENASCO C6S-4 Reciprocating 290 0 0

MENASCO DR-87 Reciprocating 125 0 0

MENASCO PIRATE A-4 Reciprocating 90 0 0

MENASCO PIRATE B-4 Reciprocating 95 0 0

MENASCO PIRATE C4 Reciprocating 125 0 1

MENASCO PIRATE C4 D4 Reciprocating 125 0 30

MENASCO PIRATE C4S Reciprocating 150 0 14

MENASCO PIRATE D4 Reciprocating 125 0 1

MENASCO PIRATE M-50 Reciprocating 50 0 0

MENASCO S PIRATE D4B Reciprocating 160 0 0

MENASCO S PIRATE DRB Reciprocating 160 0 0

MENASCO SUP PIRT D4B Reciprocating 160 0 13