The Wright Brothers' Engines
And Their Design

Kitty Hawk Flyer with original Wright engine poised on launching rail at Kill Devil Hill, near Kitty Hawk, North Carolina, 24 November 1903, the month before the Wrights achieved man's first powered and controlled flight in a heavier-than-air craft.

Reproduction of the first engine, built by Pratt & Whitney, as displayed in Wright Brothers National Memorial at Kitty Hawk. Engine is mounted in a reproduction of the Wrights' Flyer built by the National Capital Section of the Institute of the Aeronautical Sciences (now the American Institute of Aeronautics and Astronautics). Engine and plane were donated in 1963 to the National Park Service Cape Hatteras National Seashore.

SMITHSONIAN ANNALS OF FLIGHT * NUMBER 5

SMITHSONIAN INSTITUTION * NATIONAL AIR AND SPACE MUSEUM

The Wright Brothers' Engines
And Their Design

Leonard S. Hobbs

SMITHSONIAN INSTITUTION PRESS
CITY OF WASHINGTON
1971

Smithsonian Annals of Flight

Numbers 1-4 constitute volume one of Smithsonian Annals of Flight. Subsequent numbers will bear no volume designation, which has been dropped. The following earlier numbers of Smithsonian Annals of Flight are available from the Superintendent of Documents as indicated below:

• The First Nonstop Coast-to-Coast Flight and the Historic T-2 Airplane, by Louis S. Casey. 1964. 90 pages, 43 figures, appendix, bibliography. Out of print.
• The First Airplane Diesel Engine: Packard Model DR-980 of 1928, by Robert B. Meyer. 1964. 48 pages, 37 figures, appendix, bibliography. Price 60¢.
• The Liberty Engine 1918-1942, by Philip S. Dickey. 1968. 110 pages, 20 figures, appendix, bibliography. Price 75¢.
• Aircraft Propulsion: A Review of the Evolution of Aircraft Piston Engines, by C. Fayette Taylor. 1971 viii + 134 pages, 72 figures, appendix, bibliography of 601 items. Price $1.75.

For sale by Superintendent of Documents, Government Printing Office Washington, D.C. 20402—Price 60 cents

Foreword

In this fifth number of Smithsonian Annals of Flight Leonard S. Hobbs analyzes the original Wright Kitty Hawk Flyer engine from the point of view of an aeronautical engineer whose long experience in the development of aircraft engines gives him unique insight into the problems confronting these remarkable brothers and the ingenious solutions they achieved. His review of these achievements also includes their later vertical 4-and 6-cylinder models designed and produced between 1903 and 1915.

The career of Leonard S. (Luke) Hobbs spans the years that saw the maturing of the aircraft piston engine and then the transition from reciprocating power to the gas turbine engine. In 1920 he became a test engineer in the Power Plant Laboratory of the Army Air Service at McCook Field in Dayton, Ohio. There, and later as an engineer with the Stromberg Motor Devices Corporation, he specialized in aircraft engine carburetors and developed the basic float-type to the stage of utility where for the first time it provided normal operation during airplane evolutions, including inverted flight.

Joining Pratt & Whitney Aircraft in 1927 as Research Engineer, Hobbs advanced to engineering manager in 1935 and in 1939 took over complete direction of its engineering. He was named vice president for engineering for all of United Aircraft in 1944, and was elected vice chairman of United Aircraft in 1956, serving in that capacity until his retirement in 1958. He remained a member of the board of directors until 1968. Those years saw the final development of Pratt & Whitney's extensive line of aircraft piston engines which were utilized by the United States and foreign air forces in large quantities and were prominent in the establishment of worldwide air transportation.

In 1963 Hobbs was awarded the Collier Trophy for having directed the design and development of the J57 turbojet, the country's first such engine widely used in both military service and air transportation.

He was an early fellow of the Institute of Aeronautical Sciences (later the American Institute of Aeronautics and Astronautics), served for many years on the Powerplant Committee of the National Advisory Committee for Aeronautics, and was the recipient of the Presidential Certificate of Merit.

Frank A. Taylor, Acting Director
National Air and Space Museum

March 1970

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