THE LAW OF BURNING OF MODIFIED CORDITE. 



J51 



3. Reconciliation of tlie Law of Reduction. Now the equation for reduction in 

 diameter in O'OOl second at 80 F. has been determined as 



Redn. = 0'0013361 xP + 0'00028, 



where P is the pressure in tons on the square inch. 

 At 60 F. the equation is 



Redn. = 0'001223xP + 0'00028. 



Both these results are tabulated in Tables B and C. In order to justify the 

 selection of the lines shown on fig. 5 as representing the above relations, I have 

 calculated the time rise of pressure of the charge of Cord M.D. shown in fig. 4, using 

 Tables A and B. The calculated points are shown on fig. 4, and below I tabulate the 

 results for comparison : 



The variations in pressure are within the limits of experimental error, and the 

 difference in total time of combustion is only 0'000055 of a second. 



4. Investigation of the Time Rise of Pressure (Tube Form). Fig. G shows the 

 time rise of pressure of a certain sample of Tube M.D. Cordite (Batch 88). This 

 class of cordite is known as M.D.T., and one of the governing factors of its rate of 

 burning is the thickness of its annulus. On the same figure I show the calculated 

 time rise of pressure of this sample, using the law I have established. 



It is evident by inspection that the M.D.T. time rise does not directly follow the 

 cord law of reduction in diameter. The rise of pressure at the beginning is much 

 more rapid than when calculated as for cords. This difference presented a problem 



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