18 BLAIR— EXPLORATIOX OF THE UPPER AIR [March s. 



Height 204 cm. 



Width 197 cm. 



Depth 81 cm. 



Width of planes 64 cm. 



Plane space 76 cm. 



Weight 2-2 to 3.8 kg. 



There are five lifting planes, so called, and four steering. The 

 area of the lifting planes is 6.3 square meters, while that of the 

 steering planes is one third as much. Kites varying from these di- 

 mensions and necessarily therefore from these proportions are built 

 for winds higher and lower than those to which the above-described 

 kite is adapted. A type of kite which has flown in winds up to 22.5 

 meters per second has lifting planes aggregating 5.4 square meters 

 in area. Its steering planes have half this area. It is a longer, 

 narrower kite than the one whose dimensions are given above. A 

 kite that has carried an instrument in winds as low as 3.5 meters 

 per second has for the total area of its lifting planes 11.2 square 

 meters. 



The term lifting is not properly applied to any plane in the rear 

 cell of a Hargrave kite, the function of that cell being more particu- 

 larly steering. When a kite of the pattern described is sent up in a 

 fog or low cloud in which the temperature is below freezing, ice 

 crystals are found to attach themselves to the under side only of the 

 three parallel planes in the front cell, but on both sides of all other 

 planes in either cell, showing that practically all of the lifting is 

 done by the front cell. A study of the formation of these crystals 

 and the amount of ice deposited on different parts of a plane is very 

 helpful in determining the most economic width and location of 

 planes in a kite or other aeroplane. 



At Mt. Weather we attach the meteorograph to the middle back 

 rib of the first kite just behind the front cell. This insures it 

 proper ventilation during the flight and adequate protection against 

 injury in case the kite breaks away. Other, secondary, kites are 

 attached to the line at intervals depending on the wind velocity and 

 in numbers depending on the length of line put out. Their purpose 

 is to support the wire. Twelve kites with a combined lifting plane 

 area of 77.4 square meters is the greatest number we have ever used 



