Three Famous Early Aero Engines 



By Robert B. Meyer, Jr. 

 National Air Museum, Smithsonian Institution 



[With 9 plates] 



In 1853 Sir George Cayley of England created the first man-carry- 

 ing glider. This was an important milestone in the history of heavier- 

 than-air craft, but without power such aircraft could be used only 

 for sport. It was not until the advent of the successful application 

 of power to heavier-than-air craft by the Wright brothers 50 years 

 later that flying could become practical. 



During the 50-year period following 1903, improved engines made 

 possible increasingly successful flights. Throughout the first decade 

 the typical airplane was the powered glider. Having a large wing area 

 and a small amount of power for their weight, these airplanes were 

 very sensitive to wind variations, and therefore difficult to fly except 

 in calm air. For the same reasons such airplanes were slower than 

 the sports cars of their day. True powered airplanes were not built 

 until World War I. Some of these had sufficient power to "hang on 

 their propellers" briefly during certain combat maneuvers. Between 

 World Wars I and II the helicopter advanced toward a practical stage. 

 For the first time controlled vertical lift was obtained by heavier-than- 

 nir craft. This too would not have been possible without improved 

 engines having a high horsepower/weight ratio. Shortly after World 

 War II jet engines began to develop more thrust than the weight of 

 the airframe in which they were installed. Such aircraft so powered 

 are able to climb vertically. Thus in a span of 50 years heavier-than- 

 air craft advanced from gliders deriving all their lift from wings to 

 airplanes capable of deriving all their lift from engines. 



It is the engine which is the key to successful, practical flight: 

 hence the significance of this brief study of three famous aeronautical 

 engines which first powered aircraft in 1903. Each of these engines 

 is on display in the National Air Museum of the Smithsonian Insti- 

 tution. Although they are similar in that each is of the internal- 

 combustion, four-stroke-cycle, gasoline-burning type, and each is 

 equipped with automatic inlet valves, they differ from one another 

 in most other respects. 



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