Smokeless powder and its influence on gun construction by Longridge James Atkinson

Author:Longridge, James Atkinson
Language: eng
Format: epub, pdf
Tags: Gunpowder, Smokeless
Publisher: London, New York, E. & F. N. Spon
Published: 1890-03-25T05:00:00+00:00

small, and in the case of increased velocity of the projectile, will be far less than the increase due to the increased velocity of the projectile, which is not a function of the maximum pressure, but depends on the mean pressure, which is quite another thing.

74. As regards the length of gun required for the new powder, it is argued that by increasing the pressure it would be necessary also to increase the length of the gun to a practically impossible extent.

75. But this also is erroneous, for it apparently rests on the assumption that the maximum pressure can only be increased by increasing the weight of charge, and that unless the length of the chase be correspondingly increased, part of the charge will be blown out of the muzzle unburnt.

76. Now the maximum pressure depends, not altogether, nor indeed principally, on the weight of the charge, but is chiefly affected by the rate of evolution of the gas, which is regulated almost ad libitum by modifying the form and size of the grain.

It is therefore quite practicable to increase the maximum pressure, even if the weight of charge be diminished.

77. This will be the more evident after the following examination of the action of the powder in a gun.

78. In the first place, reverting to Fig. 2 which shows the pressure in the same gun when fired with charges of 33*08 B.N. and 54 Ibs. P respectively; in order to complete the curves the pressures behind the points of the maximum must be indicated.

79. According to M. Sarrau's formulae for ordinary powder, if P 0 be the pressure on the breech, P the maximum pressure on the base of the projectile, making use of English unities of pounds for weight and tons per square inch for pressure,

w and W being the respective weights of charge and projectile.

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