Tetrahedral Principle in Kite Structure 223 



general model as the Hargrave Box 

 Kite, but with triangular cells instead 

 of quadrangular, seem to fly as well as 

 the ordinary Hargrave form, and at as 

 high an angle. 



Such kites are therefore superior, for 

 they fly substantially as well, while at 

 the same time they are stronger in con- 

 struction, lighter in weight, and offer 

 less head resistance to the wind. 



and B (Fig. 7) may be constructed, as 

 shown at C and D, with advantage, for 

 the weight of the compound kite is 

 thus reduced without loss of structural 

 strength. In this case the weight of 

 the compound kite is less than the sum 

 of the weights of the component kites, 



PERSPECTIVE VIEW END VIEW 



FIG. 6 — COMPOUND TRIANGULAR KITE 



Triangular cells also are admirably 

 adapted for combination into a com- 

 pound structure, in which the aeroplane 

 surfaces do not interfere with one 

 another. For example, three triangular- 

 celled kites, tied together at the corners, 

 form a compound cellular kite (Fig. 6) 

 which flies perfectly well. 



The weight of the compound kite is 

 the sum of the weights of the three kites 

 of which it is composed, and the total 

 aeroplane surface is the sum of the 

 surfaces of the three kites. The ratio 

 of weight to surface therefore is the 

 same in the larger compound kite as in 

 the smaller constituent kites, considered 

 individually. 



It is obvious that in compound kites 

 of this character the doubling of the 

 longitudinal sticks where the corners of 

 adjoining kites come together is an un- 

 necessary feature of the combination, 

 for it is easy to construct the compound 

 kite so that one longitudinal stick shall 

 be substituted for the duplicated sticks. 



For example: The compound kites A 



while the surface remains the same. 



If kites could only be successfully 

 compounded in this way indefinitely 



6 lon&ihjclmal sticks 



15lon£,tud.nal st.cks 



FIG. 7 



we would have the curious result that 

 the ratio of weight to surface would 



