_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: 1. 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. 2. The First Airplane Diesel Engine: Packard Model DR-980 of 1928, by Robert B. Meyer. 1964. 48 pages, 37 figures, appendix, bibliography. Price 60¢. 3. The Liberty Engine 1918-1942, by Philip S. Dickey. 1968. 110 pages, 20 figures, appendix, bibliography. Price 75¢. 4. 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.