14 



The National Geographic Magazine 



A^?^ 



64-celled Tetrahedral Kite Flying from 

 Flag-pole 



Photograph by D. G. McCurdy 



structures that were composed of the 

 largest number of unit cells, and I now 

 have reason to believe that the automatic 

 stability of these kites depends more upon 

 the number of unit cells than upon the 

 presence of large empty spaces in the 

 kites ; for I have found, upon filling in 

 these empty spaces with unit cells, that 

 the flying qualities of a large kite have 

 been greatly improved. The structure, so 

 modified, seems to fly in as light a breeze 

 as before, but with greatly increased lift- 

 ing power, while the gain in structural 

 strength is enormous. 



I had hitherto supposed that if cells 

 were placed directly behind one another 

 without providing large spaces between 

 them comparable to the space between 

 the two cells of a Hargrave box kite, the 



front cells would shield the others from 

 the action of the wind, and thus cause 

 them to lose their efficiency ; but no very 

 marked effect of this kind has been ob- 

 served in practice. Whatever theoretical 

 interferences there may be, the detri- 

 mental effect upon the flying qualities of 

 a kite are not, practically, obvious, while 

 the gain in structural strength and in 

 lifting power outweigh any disadvantages 

 that may exist. I presume that there 

 must be some limit to the number of cells 

 that can be placed in close proximity to 

 one another without detrimental effect, 

 but so far my experiments have not re- 

 vealed it. 



EXPERIMENTS WITH "THE FROST KING" 



To test the matter, I put together into 

 one structure all the available winged 

 cells I had in the laboratory — 1,300 in 

 number. These were closely attached 

 together, without any other empty spaces 

 in the structure than those existing" be- 

 tween the individual cells themselves 

 when in contact at their corners. 



The resulting kite, known as "The 

 Frost King" (pages 15 and 16), con- 

 sisted of successive layers or strata of 

 cells closely superposed upon one an- 

 other. The lowest layer, or floor of 

 the structure, consisted of 12 rows of 13 

 cells each. The cells forming each row 

 were placed side by side, attached to one 

 another by their upper corners, and the 

 12 rows were placed one behind the other, 

 the rear corners of one row being at- 

 tached to the front corners of the row 

 immediately behind. The next stratum 

 above the floor had eleven rows of 14 

 cells; the next, 10 rows of 15 cells, etc., 

 each successive layer increasing in lateral 

 dimensions and diminishing in the fore- 

 and-aft direction ; so that the top layer, or 

 roof, consisted of a single row of 24 cells 

 placed side by side. One would imagine 

 that a closely packed mass of cells of this 

 kind, 1,300 in number, would have de- 

 veloped some difficult)' in flying in a 

 moderate breeze if the cells interfered 

 with one another to any material extent; 

 but this kite not only flew well in a breeze 



