Tetrahedral Principle in Kite Structure 229 



by the multiplication of smaller kites 

 into a cellular structure the results are 

 very different. My own experiments 

 with compound kites composed of trian- 

 gular cells connected corner to corner 

 have amply demonstrated the fact that 

 the dimensions of such a kite may be 

 increased to a very considerable extent 

 without materially increasing the ratio 

 of weight to supporting surface ; and 

 upon the tetrahedral plan (Fig. 16) the 

 weight relatively to the wing-surface 

 remains the same however large the 

 compound kite may be. 



The indefinite expan- 

 sion of the triangular con- 

 struction is limited by the 

 fact that dead weight in 

 the form of empty frame- 

 work is necessary in the 

 central space between the 

 sets of cells (see Fig. 6), 

 so that the necessary in- 

 crease of this space when 

 the dimensions of the com- 

 pound kite are materially 

 increased — in order to pre- 

 serve the stability of the 

 kite in the air — adds still 

 more dead weight to the 

 larger structures. Upon 

 the tetrahedral plan illus- 

 trated in Figs. 14, 15, 16, 

 no necessity exists for 

 empty frameworks in the 

 central spaces, for the 

 mode of construction gives solidity 

 without it. 



Tetrahedral kites combine in a marked 

 degree the qualities of strength, light- 

 ness, and stead}- flight ; but further ex- 

 periments are required before deciding 

 that this form is the best for a kite, or 

 that winged cells without horizontal 

 aeroplanes constitute the best arrange- 

 ment of aero-surfaces. 



The tetrahedral principle enables us 

 to construct out of light materials solid 

 frameworks of almost any desired form, 

 and the resulting structures are admi- 



rably adapted for the support of aero- 

 surfaces of any desired kind, size, or 

 shape (aeroplanes or aerocurves, etc., 

 large or small). 



In further illustration of the tetra- 

 hedral principle as applied to kite con- 

 struction, I show in figure 17 a photo- 

 graph of a kite which is not itself tetra- 

 hedral in form, but the framework of 

 which is built up of tetrahedral cells. 



This kite, although very different in 

 construction and appearance from the 

 Aerodrome of Professor Langley, which 



fig. 18— THE 



AERODROME KITE JUST RISING INTO THE AIR 

 WHEN PULLED BY A HORSE 



I saw in successful flight over the Poto- 

 mac a few years ago, has yet a suggest - 

 iveness of the Aerodrome about it, and 

 it was indeed Professor Langley's appa- 

 ratus that led me to the conception of 

 this form. 



The wing surfaces consist of hori- 

 zontal aeroplanes, with oblique steady- 

 ing surfaces at the extremities. The 

 body of the machine has the form of a 

 boat, and the superstructure forming 

 the support for the aeroplanes extends 

 across the boat on either side at two 

 points near the bow and stern. The 



