December 2019

Buhl A-1 Autogiro

First pusher Autogiro

Designer: Etienne Dormoy; Pilot: James Johnson

First flight: December 15, 1931

The first “pusher” Autogiro was created in March 1931 by the Buhl Aircraft Company, the third Autogiro Company of America (ACA) licensee (after the two Philadelphia-area companies, Pitcairn Aircraft Company and Kellett Autogiro Company). Buhl was a successful fixed-wing manufacturer and part of a large financial, manufacturing and real estate organization headquartered in Detroit. The company was founded as the Buhl–Verville Aircraft Company in 1925 with Lawrence D. Buhl as President and A. H. Buhl as Vice President.

The Buhl A-1 Autogiro design team consisted of chief engineer Etienne Dormoy, assistant chief engineer R. V. Doorn and nine other engineers, representing a significant commitment to produce a new type of Autogiro. The objective of the Buhl engineering team was to adapt a “pusher” configuration, with the engine located to the rear of the cockpit, to the Autogiro; the company’s goals for the new model were centered on visibility, accessibility, comfort and safety.

The Buhl A-1 was initially powered by a 165 hp (125 kW) Continental radial air-cooled engine, and specifically intended to “get the younger generation flying.” The unique engine placement offered unparalleled visibility, eliminated the propeller blast, provided for convenient conversation between pilot and passenger, and minimized exposure to motor heat and the smell of gasoline. The design team adopted the Pitcairn rotor hub that ACA would use on its smaller PAA-1 Autogiro then in development, and 40 ft (12.2 m) diameter rotor blades. The aircraft initially had a loaded weight of 1,850 lb (840 kg), later increased to 2,000 lb (900 kg) — compared to the 3,000 lb (1360 kg) loaded weight of the Pitcairn PCA-2. The A-1 employed the then-standard Cierva-type four-blade rotor, incorporating a Pitcairn PCA-2-type engine-powered spin-up drive, which was mounted on top of a tripod pylon just in back of the rear cockpit. The top of the tripod also attached to the upper steel-tube boom that supported the tail. Two other booms extended from the fuselage below the engine mount from either side to secure the tail, creating a ‘cage’ for the propeller and additional safety. The pilot and passenger sat in a tandem arrangement in a nacelle created by a steel tube framework covered by fabric, from which fabric covered wings extended on either side with upturned wing-tips, as in the Pitcairn PCA-2 Autogiro.

The Buhl was first flown by the company test pilot James “Jimmy” Johnson on Dec. 15, 1931, and it was immediately noted that the aircraft seemed under-powered. Thirteen days later, on the 28th, Juan de la Cierva, then-visiting America, himself confirmed that observation when he flew the Buhl. Although Cierva is reported to have given flights to General William “Billy” Mitchell and Edsel Ford, the prototype remained the only one ever built as Buhl experienced financial difficulties in 1932 and ceased aircraft production, becoming a casualty of the growing Depression. The financial difficulties experienced by the company precluded the costly development and testing necessary for certification.

The Buhl Autogiro has been restored and is now on display at the Hiller Aviation Museum in San Carlos, California.

Note: While it has been asserted that the Buhl “pusher” design was influenced by Cierva’s unbuilt patented design study for the C.21 of 1930, newly discovered evidence in the Pitcairn Archives clearly points to a more direct and earlier contribution by both Pitcairn and Cierva and strongly suggests that the “pusher” configuration had been conceived by Nov. 16, 1929 and there is additional evidence of significant contributions of Pitcairn engineers, primarily Paul Stanley.

Photo: via Bruce H. Charnov Ph.D. J.D. FRAeS

Text: Bruce H. Charnov Ph.D. J.D. FRAeS

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