Figure 69. End cap of thruster.
spring) is made as small as possible without requiring a
spring so small in diameter that it will "snake" or kink.
The piston is made of steel † and has a slenderness
ratio of 22. The slenderness ratio (L/k, where L is the
length and k is the radius of gyration) is found as
Figure 70. Piston of thruster.
whether the column is a "long" or "short" column.
Although the piston is hollow, the moment of inertia is
relatively large because of the location of the mass with
relation to the center. The hole in the piston (for the
† The modulus of elasticity for steel Is approximately 30 million psi; the modulus of elasticity for aluminum is only
about 10 million psi.