Early Experiments in Instrument Flying ' 



By James H. Doolittle, Lt. Gen., USAF (Ret.) 



Chairman, Space Technology Laboratories, Inc. 



[With 2 plates] 



The development of flight has been a gradual evolutionary process. 

 There are, however, certain landmarks along the route, and we may 

 consider that there are roughly defined areas of progress between these 

 landmarks. 



In the very early days of flying, a slight breeze could cancel or 

 delay a flight. I recall seeing my first air show in the winter of 

 1909-10 at Dominquez Field near Los Angeles. In those early days 

 it was customary for a pilot to wet his finger in his mouth and hold 

 it up. If there was enough air movement to cause uneven evaporation, 

 thus making one side cooler than the other, then there was too much 

 wind to fly. Soon, however, a modest wind was not a deterrent to 

 flight, and a good breeze was considered desirable because it shortened 

 takeoff and landing distance. 



Next came the period when a pilot was happy only as long as he 

 could see the horizon. He might fly in or through clouds, but he 

 wanted clear air and a visible horizon when he came back through 

 them. 



This paper will deal with the next era, at the end of which a visible 

 horizon was not required and during which it became possible to fly, 

 and even land, without seeing outside an instrumented cockpit. Today 

 aircraft fly safely and reliably in all but the most inclement weather, 

 and I look forward to the not very distant future when the airplane — 

 or its successor — will fly absolutely regardless of weather and will 

 then become not only the fastest, but the most reliable form of 

 transportation. 



^ The third Lester Gardner lecture given at the Massachusetts Institute of Technology. 

 Apr. 28, 1961 ; somewhat modified for publication. A repeat of the lecture was given at 

 the Smithsonian Institution on Sept. 28, 1961, by permission of the Massachusetts Institute 

 of Technology. 



337 



