Hiroto HABU

The cost reduction is currently important for the development of space launch systems. The replacement of the special purpose product by the general one is effective for the reduction in cost. The solid motor side jet system is loaded the low temperature gas generator propellant (GGP) which is composed of a special purpose material. The combustion gas temperature of GGP should be controlled up to 1400 K because of the system requirement. That is why ammonium nitrate (AN) is selected as an oxidizer for GGP. The composition and combustion characteristics of AN based GGP for the launch vehicle side jet system were investigated. The gas temperature was previously estimated by calculation and verified directly by the static firing test. This work is the first step for the improved GGP development.

A nozzle and a combustion chamber of a small liquid fuel rocket engine used as an upper stage engine of solid propellant rocket and an apogee engine of a satellite requires to operate without cooling by cryogenic fuels. From this reason, materials that can be used at high temperature in oxidizing environment are highly required for such thrusters. To meet with this demand, trial manufacture of a thruster made of SiC fiber-reinforced SiC matrix composite are carried out in this study. A SiC/SiC composite thruster was successfully manufactured by CVI and PIP combination process. The thruster passed the proof pressurize test up to 5.0 MPa (2.5 times higher than operation pressure, 2.0 MPa). However, First trial ended in an explosion just after the ignition of the engine. By changing engine start sequence (provide fuel and oxidizer just before the ignition to avoid penetration of the liquid into the pores), 30s continuous oneration of the engine succeeded.

The combustion phenomena of high energetic materials, which accompany the rapid production of much amount of gases and heat, have been focused on in the fields of automobile safety application such as airbag system. This paper describes our study on the combustion characteristics and combustion model of gas generants for airbag inflators.