RIGID STABLE AEROPLANES. 387 



If the string and weight are swung without the rigid 

 stable aeroplane, the string can only describe a blunt cone 

 with the apex upwards. When the aeroplane is tied to the 

 weight, the apex of the cone is downwards, indicating that 

 the aeroplane at that velocity is lifting more than the 

 weight. A great increase of velocity adds enormously to 

 the weight on the aeroplane, as the weight is trying to 

 flatten the inverted cone. 



Used as kites, these rigid stable aeroplanes are superior 

 to the very best cellular kites I can make ; they are lighter, 

 pull harder per square foot, attain a greater angle of eleva- 

 tion, and have fewer parts. When their qualities become 

 known, the two-celled kite will be considered a barbarism 

 of the past. The ladder kite that was experimented with 

 in 1897 (Fig. 4) is a very light and compact form of 

 multiplane lifting surface. The twenty planes are 1 foot 

 5| inch square; they are spaced one foot apart. The two 

 highest planes are strutted into the box form; the rest of 

 the side surfaces are quite loose and only tightened by the 

 lift of the planes. The best way to fly this kite is to lay 

 it out on the ground in either of the dotted positions shown 

 on the plan. Pull a little on the string that is not lying 

 on the ground, thus squaring the rhomboidal shape of the 

 kite, and it will at once assume the upright position. 

 Similarly by pulling either string the kite will lay itself 

 down without damage on the side that it is pulled. If you 

 pull A the kite lies down at C. If you pull B it lies down 

 at D. The kite, when on the ground, does not roll away 

 to leeward as one might expect. 



T— Dec. 1, 1909. 



