Harlan D. Fowler

Harlan D. Fowler (1895–1982) was an American inventor, writer, and airplane engineer. He is known for creating the Fowler flap, a high-lift device found on the trailing edge of many modern commercial aircraft wings. The flap moves backward and rotates downward, increasing the wing’s curvature, area, and lift, while also creating one or more slots. This complex motion requires special guidance rails on the wing’s lower surface.

Fowler began designing and testing his flap privately in the summer of 1927 with mechanic Stanley Crowfoot, funding the work himself. Testing by NACA engineer Fred Weick showed the flap could reduce landing speed, shorten takeoff and landing runs, and improve climb.

Early aircraft to use the Fowler flap included the Martin 146 prototype (1935) and the German Fieseler Fi 97. Later adopters were the Boeing B-17, B-29, and Lockheed P-38 Lightning. In 1948, Fowler published Fowler Flaps for Airplanes: An Engineering Handbook.

Life

Born Harlan Davey Fowler on June 18, 1895, in Sacramento, California, he built man-lifting kites as a teenager. He married twice and had two children. His aeronautical career began in 1917 with the Signal Corps, and he later worked as assistant engineer in charge of design at McCook Field in Dayton, Ohio. He served as an independent consultant for Fokker, Glenn L. Martin, Convair, Douglas Aircraft, the Bureau of Aeronautics, and the U.S. Air Force.

From 1922 to 1925, he worked with G. Elias & Brother, the Aeromarine Plane and Motor Company, and the Naval Aircraft Factory. He also worked at Pitcairn Aircraft Company designing the Mailwing, and in 1928 became chief aeronautical engineer for John M. Miller III of the Miller Aviation Corporation. In May 1929, he founded Fowler Airplane Wings Inc., hoping to market his flap just before the Wall Street Crash. He later became president of the Fowler Aircraft Company, formed from the insolvent Hardman Aircraft Products Inc. of San Diego.

Despite hearing difficulties that required a hearing aid, he persistently lobbied NACA with ideas. NACA engineer Ken Mort helped him build models and test concepts. Fowler developed his flap when airplanes were still fabric-covered. He retired in 1975 and died in 1982.