To develop an experimental small hybrid rocket with a swirling gaseous oxygen flow type engine, we made a flight model engine. Burning tests of the engine showed that a maximum thrust of 692 N and a specific impulse of 263 s (at sea level) were achieved. We designed a small hybrid rocket with this engine. The rocket measured 1.8 m in length and 15.4 kg in mass. To confirm the flight stability of the rocket, wind tunnel tests using a 112-scale model of the rocket and simulations of the flight attitude and trajectory were carried out. A flight test was conducted at Taiki-cho, Hokkaido, Japan on March 2001. The rocket reached an altitude of about 600 m, thus recording the first successful flight of a hybrid rocket in Japan. For the next stage, future issues to develop larger hybrid rockets using a swirling liquid oxygen flow type engine are discussed, and preliminary burning tests of the engine have been carried out.

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We have been developing a small rocket without combustion process designed for safe, cost-effective and eco-friendly propulsion system. We refer to the engine system of rocket as CEES (Cryogenic, Economical, Ecological, Safe) engine. The engine is a kind of cold gas engine which uses cryogenic liquid nitrogen and heated water as propellants. It is intended that pressure increase in the mixing chamber gets closer to that of a combustion engine system in such a way to take effectually advantage of evaporation of liquid nitrogen. From both simple analysis and experiments, it is found that the thrust can be approximately 540 N and is amply sufficient to fly a rocket. On the basis of the result of the thrust experiments we designed and developed a small rocket equipped with the CEES engine. On 20th March 2005 we launched the rocket successfully. It reached a height of approximately 60 m. The flight path is almost consistent with the analytical result derived from the thrust experiments. The small rocket using engine system without combustion, which is able to take up payloads, was first launched in the world as far as we know.

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A space educational program in Tokai University Shonan campus (TUS) was established in 1995 for a purpose of the space science and engineering education. We have mainly two space programs, the one is sounding rocket experiment collaboration with University ofAlaska Fairbanks (UAF) and the other program is development and launch of small hybrid rockets. In January 2000 and March 2002, two collaborative sounding rockets were launched from the launch site in Alaska and all of handmade instruments were successfully carried to the apogees of 79 km and 89km high, respectively. Tokai students made two fluxgate magnetometers and analogue sun sensor, and Alaska students made accelerometers, telemeters, recovery system and so on. The third student sounding rocket is going to launch on March in 2006. In 2001, the first Tokai hybrid rocket was launched at Alaska and Tokai students carried accelerometer, bolometric altimeter and flight computer on the payload. After then, we could have launching experiments at Hokkaido and atAkita in Japan and Tokai five hybrid rockets were launched during 2004-2005. The Tokai space education program provides students with the opportunity for hands on experience to design, to construct, to test sounding rocket payloads and hybrid rockets by use of low cost devices, and to analyze acquisition data after launches. This program has proven to be very effective in providing students with practical, real-world engineering design experience and this also allows students to participate in all phases of a sounding rocket mission. Also students learn scientific knowledge, engineering technique and system management through experiences of cooperative teamwork, presentations and collaborations. In this paper, we introduce the space education program in Tokai and discuss advantages and some problems in promotion of the education.

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To enhance the gasification rate of hybrid rocket motor that is essential for its practical use in a small launcher, the authors have been developing a new type of hybrid rocket named CAMUI as an abbreviation of Cascaded Multistage Impinging-jet. The fuel grain in the CAMUI motor is a set of cylindrical fuel blocks with two ports in axial direction. To develop a prediction method of the regression progress in the CAMUI hybrid motor, the authors investigated regression progress of CAMUI fuel with a 70 kgf thrust class static firing test motor, varying liquid oxygen flow rate and burning duration. By adopting least square method to the experimental data, we obtained empirical constants in regression formulae for each burning surface. The calculated regression distances agree well with the experimental value, showing the validity of the obtained regression formulae. It is possible to predict the history of the fuel flow rate by using the regression formulae of burning surfaces, assuming that the regression of each surface progresses in one direction and independently. The predicted chamber pressure history is in good agreement with the experimental one, showing the validity of the method to predict the fuel gasification rate.

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The fly-back system of CAMUI (CAscaded MUltistage Impinging-jet) hybrid rocket has been developed. At the first stage, we conducted the gliding test of a Space-shuttle type winged vehicle. In the test, the winged vehicle was carried by a radio-controlled (RC) airplane, separated at the altitude of 250 m, glided and landed. The launching test of the vehicle was carried out by using a model rocket engine. At the second stage, we developed a delta wing to install to the CAMUI hybrid rocket. The aerodynamic characteristics of a hybrid rocket with the delta wing were investigated by a wind tunnel, and the flight performance of the winged vehicle was checked by using water rocket. The launching and fly-back test of the CAMUI hybrid rocket assembled with the delta wing was conducted successfully. At the third stage, we have developed a low drag winged CAMUI hybrid rocket to reach to the 60 km altitude. The avionics for the fly-back system has been also developed, and the performance has been confirmed by the autonomous control test of a motor glider and by the launching and fly-back test of the winged CAMUI hybrid rocket.

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