超小型深宇宙探査機用ハイブリッドキックモータの開発

抄録

To realize deep space missions on a limited budget, a hybrid rocket kick motor for a laboratory-scale space probe being kicked from GTO to a deep space trajectory is being developed. Nitrous Oxide (N2O) is selected as an oxidizer to allow for long-term non-cryogenic storage in space, and High Density Polyethylene (HDPE) is selected as a fuel for safety and affordability.Two fuel configurations are being considered for this mission: a conventional tubular fuel grain, and a Cascaded Multistage Impinging-jet (CAMUI) type fuel grain. This study presents results and analysis from the first set of CAMUI-type static firing tests employing N2O as an oxidizer, with the aim of clarifying performance related issues such as achieving an optimum oxidizer to fuel mass ratio O/F of around 6~7, quantifying fuel regression rate etc. for design purposes. The results of two gaseous N2O firing tests and two liquid N2O firing test lead to the following two conclusions. The use of liquid N2O will be necessary to realize an appropriate flowrate for space applications, and CAMUI-type motors may not be suitable for achieving optimum O/F because they tend to burn extremely fuel rich. Additional firing tests are necessary to quantify the fuel regression rate in CAMUI-type fuel and conventional tubular fuel grains using N2O.