32 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 



After studying various forms for the hull or body of the prospective aero- 

 drome, I was led to adopl the lines which Nature has used in the mackerel as 

 most advantageous so far as the resistance of the air was concerned, but it, proved 

 to be difficult in construction to make the lines of the how materially different 

 from those of the stern, and in this first model the figure was symmetrical 

 throughout. 



As 1 wish that my experience may be of benefit to the reader, even in its 

 failures, I will add that 1 made the not unnatural mistake of building on the plan 

 on which the hull of an ordinary ship is constructed; that is, making the hull 

 support the projecting bowsprit and other parts. In the aerodrome, what cor- 



resp Is to the bowsprit must project far in advance of the hull to sustain the 



front wings, and a like piece must project behind it to sustain the rear wings ami 

 the tail, or the supporting surfaces of whatever kind. The mistake of the con- 

 struction lay in disjoining these two and connecting them indirectly by the in- 

 sufficiently strong- hull which supported them. This hull was formed of longi- 

 tudinal U-shaped ribs of thin steel, which rested on rings made of an alloy of 

 aluminum, which possessed the lightness of the latter metal with very consider 

 able toughness, but which was finally unsatisfactory. I may say parenthetically 

 that in none of the subsequent constructions has the lightness of aluminum been 

 found to compensate for its very many disadvantages. The two rods, which were 

 cadi 1 metre in length, were with difficulty kept rigorously in line, owing to the 

 yielding of the const ructionally weak hull. It would have been better, in fact, to 

 have carried the rod straight through at any inconvenience to the disposition of 

 the boilers and the engine. 



I may add that the sustaining surfaces, which were to be nearly flat wings, 

 composed of silk stretched from a steel tube with wooden attachments, were to 



'Tli.: following table taken from "Experiments in Aerodynamics," p. in;, gives t lie data for soaring of 

 30i 4.8 Inch planes, weight 500 grammes. 



The relations shown in the ahove table hold t ru Ij in ease of planes supporting about 1 . 1 pounds to each 



squui ustaiuing area. For a different proportion of area to weight, other conditions would obtain. 



