CHAPTER II 

 GENERAL CONSIDERATIONS 



In the development of man-carrying flying machines two well-defined paths 

 are open. First: Starting with gliding machines, in which gravity furnishes 

 the motive power, the operator may by practice acquire sufficient skill in con- 

 trolling them to warrant the addition of propelling mechanism, and individual 

 skill in control may be gradually replaced by automatic controlling mechan- 

 ism. Second: From self-propelled models, possessing automatic-equilibrium 

 emit rolling mechanism, and of a sufficient size to furnish determinative data, 

 one may, by proper modification in size and construction, progress to an auto- 

 matically controlled man-carrying machine in which, for ideal conditions, no 

 especial skill on the part of the operator is required. Each method has its 

 advantages. 



After concluding his earlier and purely physical researches, the results of 

 which were embodied in " Experiments in Aerodynamics," Mr. Langley was so 

 firmly convinced of the practicability of mechanical flight that he undertook 

 the construction of the model aerodromes in order to demonstrate it. It is very 

 doubtful if at any time, prior to the successful flights of the models in 1896, he 

 seriously contemplated the construction of man-carrying machines. His object 

 in developing the models was not, therefore, to furnish a prototype for a large 

 machine, but merely to demonstrate the feasibility of mechanical flight ; and this 

 be did. This is shown very clearly by the closing remark of the article he pub- 

 lished in 1897, describing the flights of the models. " I have now brought to a 

 close the portion of the work which seemed to be specially mine — the demon- 

 stration of the practicability of mechanical flight — and for the ne\1 stage, which 

 is die commercial and practical development of the idea, it is probable that the 

 world may look to others." 1 When he later undertook the construction of the 

 large machine for the War Department it was natural that, with the inspiring 

 sight of the models in flighl still fresh in his mind, he determined to use as a 

 prototype these successful machines, which were the only things of human con- 

 si ruction that had ever really flown for any considerable distance. 



Not being an engineer, and realizing thai to pass from the construction of 

 models to that of man-carrying machines involved the solution of many engi- 

 neering problems, Mr. Langley, in the spring of L898, sought the advice of Dr. 

 I.'. II. Thurston, who had from the first manifested the deepest interest in Ins 



•"The Flying Machin. McClure's Magazine, June, 1897. 

 128 



