NO. 2 



METHOD OF REACHING EXTREME ALTITUDES 



13 



EXPERIMENTS IN AIR WITH SMALL STEEL CHAMBERS 

 An apparatus was next constructed, with a view to increasing the 

 efficiency, embodying' three radical changes, namely, the use of 

 smokeless powder, of much higher heat value than the black powder 

 employed in ordinary rockets ; the use of a strong steel chamber, to 

 permit employment of high pressures ; and the use of a tapered 

 nozzle, similar to a steam turbine nozzle, to make available the work 

 of expansion. 



Two sizes of chamber were used, one ^ inch diameter, and one 

 I inch diameter. The inside and outside diameters of the smaller 

 chamber, figure 2(a), were, respectively, 1.28 cm. and 3.63 cm. The 



Fig. 2. 



nozzle, polished until very smooth, was of 8 degrees taper, and was 

 adapted to permit the use of two extensions of different lengths. The 

 length of the chamber, as the distance 1 in the figure will be called, 

 could be altered by putting in or removing cylindrical tempered steel 

 plugs of various lengths, held in place by the breech block. Plate 2, 

 figure 3, is a photograph of the chamber, with the no'zzle of medium 

 length in position. Plate 2, figure 4, shows the same, taken apart; 

 and figure 5 shows the chamber with the medium nozzle replaced 

 by the long nozzle. 



Two small chambers were used, practically identical in all respects ; 

 one of the soft tool steel, and one of best selected nickel steel gun 

 barrel stock, treated to give 100,000 lbs. tensil strength, for which the 

 writer wishes to express his indebtedness to' the Winchester Repeat- 

 ing Arms Company. 



The charge of powder, P, figure 2, was fired electrically, by a hot 

 wire in the following way : A fine copper wire, w, 0.12 mm. diameter, 

 passed through the wadding, figure 2 (b), consisting of two disks of 

 stiff cardboard, and this copper wire joined a short length of platinum 

 or platenoid wire of o.i mm. diameter, f, extending across the inner 



