Abstract: A rotational brake member controls the rotational velocity of an electric generator assembly housed within a projectile. The assembly includes an air-driven turbine and an electric generator. The brake member is affixed to the turbine which drives a rotatable element of the generator to produce electric power. The brake member is formed from an elastically deformable material and is adapted to contact the stationary surface proximate the periphery of the brake member at a predetermined angular velocity. In addition, a shock absorbing member formed from an inelastically deformable material is positioned to absorb shock to the turbine when the projectile is fired. Preferably, the generator further includes an elastomeric seat for biasing the turbine away from the shock absorbing member after the projectile has been fired.