*d. Estimation of Propellant Charge Weight.*

(1) *Catapults and removers.*

*(a) *The propellant charge weight in pounds, C, required for a catapult or remover may be estimated

using equation (31).

and where

*F *= propellant impetus

*e *= overall efficiency (use 0.10 as a representative figure for catapults and removers)

*y *= ratio of specific heats

*m *= propelled mass

*m*' = modified propelled mass

*a *= angle between direction of thrust and-horizontal

*V *= velocity at separation

*S *= stroke to separation

*(b) *In the equation for modified propelled mass, the factor 1.03 is used to account for the affects of

sin a corrects for the angle of thrust with the horizontal. For downward

ejection, the plus sign in equation (32) would be replaced by a minus sign.

*(c) *Figure 21

for determining charge weight is

based upon the following equation:
2

C=kWv

(4)

This equation is a modification of equation (31). The constant, *k, *was determined by letting γ =1.25,

*e *= 0.10, F = 3.1X105 for catapults and 3.6X105 ft lb/lb for removers, and m' = 1.1m. In addition, k

includes a term to permit propelled weight to be substituted for mass and another term to give the

-5

2

2

answer (charge weight) in grams. The constant was found to be: k =6.25 x10 gm sec /lb ft for

-1

2

2

catapults, and 5.38X10 gm sec /lb ft for removers.

(2) *Thrusters.*

*(a) *The charge weight for a thruster may be estimated using equation (33).

Where:

*F *= total resistive force

*S *= piston stroke

*e *= overall efficiency (0.10 is a representative value)

*γ *= ratio of specific heats

*(b) *Figure 22 is

based on

the following equation:
**55**