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Acknowledgments

As is probably usual with most notes such as this, however short, before completion the author becomes indebted to so many people that it is not practical to record all the acknowledgments that should be made. This I regret extremely, for I am most appreciative of the assistance of the many who responded to my every request. The mere mention of the Wright name automatically opened almost every door and brought forth complete cooperation. I do not believe that in the history of the country there has been another scientist or engineer as admired and revered as they are.

I must, however, name a few who gave substantially of their time and effort and without whose help this work would not be as complete as it is. Gilmoure N. Cole, A. L. Rockwell, and the late L. Morgan Porter were major contributors, the latter having made the calculations of the shaking forces, the volumetric efficiency, and the connecting rod characteristics of the 1903 engine. Louis P. Christman, who was responsible for the Smithsonian drawings of this engine and also supervised the reconstruction of the 1905 Wright airplane, supplied much information, including a great deal of the history of the early engines. Opie Chenoweth, one of the early students of the subject, was of much assistance; and I am indebted to R. V. Kerley for the major part of the data on the Wrights' shop engine.

Also, I must express my great appreciation to the many organizations that cooperated so fully, and to all the people of these organizations and institutions who gave their assistance so freely. These include the following:

• Air Force Museum, Wright-Patterson Air Force Base, Ohio
• Carillon Park Museum, Dayton, Ohio
• Connecticut Aeronautical Historical Association, Hebron, Connecticut
• Fredrick C. Crawford Museum, Cleveland, Ohio
• Historical Department, Daimler Benz A. G., Stuttgart-Untertürkheim, West Germany
• Engineers Club, Dayton, Ohio
• Deutsches Museum, Munich, West Germany
• Educational and Musical Arts, Inc., Dayton, Ohio
• Henry Ford Museum, Dearborn, Michigan
• Franklin Institute, Philadelphia, Pennsylvania
• Howell Cheney Technical School, Manchester, Connecticut
• Library of Congress, Washington, D.C.
• Naval Air Systems Command, U.S. Navy, Washington, D.C.
• Science Museum, London, England
• Victoria and Albert Museum, London, England

In particular, very extensive contributions were made by the Smithsonian Institution and by the United Aircraft Corporation through its Library, through the Pratt & Whitney Aircraft Division's entire Engineering Department and its Marketing and Product Support Departments, and through United Aircraft International.

The Beginnings

The general history of the flight engines used by the Wright Brothers is quite fascinating and fortunately rather well recorded.[1] The individual interested in obtaining a reasonably complete general story quickly is referred to three of the items listed in the short bibliography on page 69. The first, The Papers of Wilbur and Orville Wright, is a primary source edited by the authority on the Wright brothers, Marvin W. McFarland of the Library of Congress; a compact appendix to volume 2 of the Papers contains most of the essential facts. This source is supplemented by the paper of Baker[2] and the accompanying comments by Chenoweth, presented at the National Aeronautics Meeting of the Society of Automotive Engineers on 17 April 1950. Aside from their excellence as history, these publications are outstanding for the manner in which those responsible demonstrate their competence and complete mastery of the sometimes complex technical part of the Wright story.

The consuming interest of the Wrights, of course, was in flight as such, and in their thinking the required power unit was of only secondary importance. However, regardless of their feeling about it, the unit was an integral part of their objective and, due to the prevailing circumstances, they very early found themselves in the aircraft engine business despite their inexperience. This business was carried on very successfully, against increasingly severe competition, until Orville Wright withdrew from commercial activity and dissolved the Wright Company. The time span covered approximately the twelve years from 1903 to 1915, during the first five years of which they designed and built for their own use several engines of three different experimental and demonstration designs. In the latter part of the period, they manufactured and sold engines commercially, and during this time they marketed three models, one of which was basically their last demonstration design. A special racing engine was also built and flown during this period. Accurate records are not available but altogether, they produced a total of something probably close to 200 engines of which they themselves took a small number for their various activities, including their school and flying exhibition work which at one time accounted for a very substantial part of their business. A similar lack of information concerning their competition, which expanded rapidly after the Wright's demonstrations, makes any comparisons a difficult task. The Wrights were meticulous about checking the actual performance of their engines but at that time ratings generally were seldom authenticated and even when different engines were tried in the same airplane the results usually were not measured with any accuracy or recorded with any permanency. There is evidence that the competition became effective enough to compel the complete redesign of their engine so that it was essentially a new model.

For their initial experimentation the Wrights regarded gravity as not only their most reliable power source but also the one most economical and readily available, hence their concentration on gliding. They had correctly diagnosed the basic problem of flight to be that of control, the matter of the best wing shapes being inherently a simpler one which they would master by experiment, utilizing at first gravity and later a wind tunnel. Consequently, the acquisition of a powerplant intended for actual flight was considerably deferred.

Nevertheless, they were continuously considering the power requirement and its problems. In his September 1901 lecture to the Western Society of Engineers, Wilbur Wright made two statements: "Men also know how to build engines and screws of sufficient lightness and power to drive these planes at sustaining speed"; and in conjunction with some figures he