e. Equation (37) governs the production of propellant gas in a multiperforated propellant before the web has burned
through; equation (38) governs the production of the gas after the web has burned through. With propellant grains in
which there is no perforation or only one perforation, equation (38) is not needed because a zero web fraction
corresponds to the complete consumption of the propellant. These equations are close approximations of the true
geometrical form functions, and the coefficients are defined in terms of propellant dimensions.
f. The coefficients for the geometric form functions of single-perforated grains are:
Where:
w = propellant web
D = diameter of grain
d = diameter of perforation
L = propellant grain length
g. Coefficients for form functions of seven-perforated grains are presented in table XIV.
D/d
Coef
L/d
1.5
2.0
2.5
3.0
3.5
Ke..................
0.8490
0.8362
0.8335
0.8316
0.8303
8 K1..................
0.9111
0.9300
0.9414
0.9490
0.9544
K2..................
0.0702
0.0938
0.1079
0.1174
0.1241
Ke..................
0.8563
0.8516
0.8487
0.8468
0.8455
10 K1..................
0.9447
0.9673
0.9808
0.9898
0.9963
K2..................
0.0884
0.1157
0.1321
0.1430
0.1508
Ke..................
0.8652
0.8603
0.8574
0.8554
0.8541
12 K1..................
0.9673
0.9923
1.0073
1.0173
1.0245
K2..................
0.1021
0.1320
0.1499
0.1619
0.1785
(1) Equations of definition of volume.
V1=V0 + A1s
(39)
before telescoping tube stop
V2 = V0 + (A1 - A2) S1 + A2S
after telescoping tube stop
(40)
Where:
V1 = volume during telescoping tube stroke
V0 = initial free volume
A1 = piston area during telescoping tube stroke
V2 = volume during inner tube stroke
A2 = piston area during inner tube stroke
S1 = telescoping tube stroke
s = length of stroke at time t
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