250 



MAJOR J. H. MANSELL: INVESTIGATION OP 



burning does not run along the cordite rapidly. This can easily be seen by burning 

 cordite in the air, when it burns slowly along its length in the manner of slow-match 

 and the flash is not rapidly transmitted as with gunpowder. Consequently, in the 

 vessel the lighted ends of the cords burn non-explosively until such time as the 

 vessel is completely filled with flame at a high temperature. At that moment there 



-OO2 -CO! -006 -008 -OIO -012 -QM -OI6 -CHS -O2O 



Reduction in diameter- Inches. 



-O22 -O24 -O26 -O2& 



Fig. 5. M.D. cordite reduction in diameter in 001 second when burning under a given average pressure. 



is a definite pressure in the vessel which tends to separate the cords one from another. 

 The cords now are lighted over their whole length and the true time of combustion 

 by parallel surfaces commences. The constant C is thus due to the amount of gas 

 produced by combustion of the ends of the sticks, when regarded as if produced by 

 combustion over the whole length of the stick. The error introduced into the length 

 of the sticks by this assumption is insignificant and can be neglected. 



If this explanation is correct, one would expect the amount of cordite burnt previous 

 to complete ignition of the charge to be independent of the temperature. That this 

 is so was experimentally determined before the theoretical explanation of the constant 

 suggested itself to me. Undoubtedly the time to complete ignition is different with 

 change of temperature of the cordite, but this does not affect the ultimate time rise. 

 Its sole effect is a small variation in the hang-fire of the charge. Theoretically the 

 constant C must vary with the density of loading. It has been determined at a 

 density of 0'25, and the small variation at lower densities does not affect the general 

 accuracy of the calculation. 



