LANGLEY MEMOIR ON MECHANICAL FLIGHT 



Part 1. 1887 to 1896 



By S. P. LANGLEY 



Edited by CHARLES M. MANLY 



CHAPTER I 

 INTRODUCTORY 



I 1 announced in 1891, 2 as the result of experiments carried on by me 

 through previous years, that it was possible to construct machines which would 

 give such a velocity to inclined surfaces that bodies indefinitely heavier than 

 the air could be sustained upon it, and moved through it with great velocity. 

 In particular, it was stated that a plane surface in the form of a parallelogram 

 of 76.2 cm.xl2.2 cm. (30x4.S inches), weighing 500 grammes (1.1 lbs.), could 

 be driven through the air with a velocity of 20 metres (65. G feet) per second 

 in absolutely horizontal flight, with an expenditure of 1/200 horse-power, or, in 

 other terms, that 1 horse-power would propel and sustain in horizontal flight, 

 at such a velocity (that is, about 40 miles an hour), a little over 200 pounds 

 weight of such surface, where the specific gravity of the plane was a matter of 

 secondary importance, the support being derived from the elasticity and iner- 

 tia of the air upon which the body is made to run rapidly. 



It was further specifically remarked that it was not asserted that planes of 

 any kind were the best forms to be used in mechanical flight, nor was it asserted, 

 without restrictions, that mechanical flight was absolutely possible, since this 

 depended upon our ability to get horizontal flight during transport, and to Leave 

 the earth and to return to it in safety. Our ability actually to do this, it was 

 added, would result from the practice of some unexplored art or science which 

 might be termed Aerodromics. but on which I was not then prepared to enter. 



I had at that time, however, made certain preliminary experiments with 

 flying models, which have been continued up to the present year, 3 and at the 

 same time I have continued experiments distinct from these, with the small 

 whirling-table established at Washington. The results obtained from the latter 

 being supplemental to those published in " Experiments in Aerodynamics," and 



'"Experiments in Aerodynamics." Smithsonian Contributions to Knowledge, Vol. 27, 1891. 

 : This chapter was written almost entirely by Mr. Langley in 1897. 

 ' 1897. 



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