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  • Development of CAMUI Hybrid Rocket to Create a Market for Small Rocket Experiments

    Paper number



    Associate Professor Harunori Nagata, Hokkaido University, Japan


    Mr. Mitsunori Ito, Japan


    Prof. Isao Kudo, Japan


    Mr. Takenori Maeda, Japan


    Dr. Tsuyoshi Totani, Hokkaido University, Japan


    Mr. Tsutomu Uematsu, Japan


    Mr. Mikio Watanabe, Japan



    A joint research team of universities and private companies in Hokkaido, Japan has been organized to develop a small-scale reusable launch system based on hybrid rocket.  The main purpose is to drastically reduce the cost of rocket experiments and thus attract potential users such as metrological and microgravity researchers.  Although the idea of the hybrid rocket is old, the crucial problem of slow gasification rate of solid fuel has not been overcome, and no hybrid rocket has been in practical use as a small launcher.  To accelerate the gasification rate of solid fuel, a new fuel grain design is developed.  We separated conventional cylinder-shape solid fuel with a central port into multiple cylinder blocks with two ports.  The key design of this engine, designated as CAMUI as an abbreviation of “Cascaded Multistage Impinging-jet”, is that the gas flow repeatedly collides with the solid fuel surface to accelerate the heat transfer to the fuel.  In the authors’ experience, it is possible to increase the thrust density (i.e., thrust per unit volume of the combustion chamber) to at least three times more than the conventional type.
         To install a LOX regenerative cooling system in a small launcher, we devised a valveless supply system (with no valves in the liquid oxygen flow line).  The combustion chamber and the LOX tank are concentric cylinders, the outer side is LOX tank and the inner one is the combustion chamber.  The liquid oxygen flows throughout orifices at the bottom of the tank, and then goes upward while cooling the chamber’s sidewall, before being injected into the chamber. Since the top of the liquid oxygen is under the injector, unless the tank is pressurized, liquid oxygen is not supplied to the combustion chamber.
    To confirm that the valveless supply system operates normally under a launch environment, we conducted a launch-verification test with a test vehicle of 1.6 m in overall length and 10.5 kg in initial weight.  The engine equipped with a combustion chamber of 300 mm in length and 50 mm in inner diameter generates about 50 kgf thrust by burning 450g PMMA fuel for about four seconds.  The highest altitude limit was set to about 900 m for safety reasons. The launch experiments were conducted three times in March 2002, January 2003 and March 2004 at Taiki-cho, Hokkaido, Japan. All three were successfully completed.
         We are now proceeding with development of a larger-size CAMUI hybrid rocket for meteorological observation and microgravity experiments. In the meteorological-observation mission, the launcher will ascend to an altitude of 60 km carrying 4 kg of experimental instruments to collect samples of atmospheric constituents. In the microgravity experiment mission, it will lift up 10 kg of experimental instruments to an altitude of 110 km and provide a microgravity environment for three minutes during its ballistic flight at altitudes of 70 to 110 km. We estimate that the launch cost will be about one million yen level for the meteorological observation model and less than five million yen for the microgravity experiment model.
    Abstract document


    Manuscript document

    IAC-05-C4.P.21.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.