Affective factors investigation on variable thrust pintle motor performance

Controllable thrust propulsion technologywill be a solution to the propulsion requirements for the next generation of missiles. Pintle controlled solid propulsion is one approach to achieving this goal. An analytical model for pintle motor was established based on the classical equilibrium pressure equation and thrust equation of rocket motor. Key factors affecting the pintle motor performance, both pressure and thrust adjusting ratio, were analyzed, including the solid propellant pressure exponent and nozzle throat area. Sensitivities of pressure and thrust adjusting ratio on throat area and solid propellant pressure exponent were studied. Experiments were taken out for different pressure and thrust adjusting ratio, utilizing the non-coaxial pintle motor experimental system. Different controlling schemes were studied, not only including simple scheme with one single adjustment, but also including complex adjustment scheme, such as changing from low state to high state, and then back to another low state. Experimental results show great verification to the analytical model of pressure and thrust adjusting ratio. The results also show that much higher chamber pressure is required for high thrust adjusting ratio, bringing a critical requirement to motor design. The thrust coefficient of nozzle might be decreasing along with the pressure ratio increasing under certain circumstance.