NERVA rocket trajectory corridor over black Sea

The constraints during the atmospheric ascent of the small NERVA rocket launcher are investigated, especially in regard to the limited flight envelope and mass optimization requirements. The usual flight ascent optimization faces in this case additional constraints, which must be solved with minimum losses of mass efficiency of the vehicle. A methodology of investigating the best ascent control laws is presented with emphasize on the second stage of the vehicle, regarding both the gas-dynamic controller system of the control unit and the accuracy of the inertial sensors of the self-guidance onboard system. The methodology is also focused on accommodating the high orbital insertion requirements of the gravity turn trajectory with a low-cost, highly secure flight controller system. Minimum technological modifications of the existing rocket propulsion system of the second stage are considered, which is a typical liquid propellant stage with aerodynamic and gas-dynamic attitude controls. Possible technological solutions are analyzed and compared regarding the accessibility of the ascent trajectories and optimal constrained solutions to the safety problem. The constraints are of safety, technological and international nature.