Shinichiro Tokudome

Erosive Burning of Aluminized Composite Propellants: X-Ray Absorption Measurement, Correlation, and Application

The erosive burning effects in a small test motor loaded with highly aluminized practical composite propellants have been investigated in detail by using an X-ray absorption diagnostics to measure the propellant local regression. The motor was specially designed to have two propellant slabs and was called as DSM (Double Slab Motor). Significant erosive burning was forced to occur in the motor for several combustion pressure levels and ranges of mass flux in the port. A new simple correlative equation, which includes the effects of mass flux, mass burning rate, combustion pressure and motor scale, was derived from the results of DSM firing tests. The parameters of correlative equation were finally determined by taking into account of the experimental results of cylindrical test motors. In addition, the correlative equation was applied to practical full-scale motors, and the predicted pressure-time curves agreed well with experiments. As the result, a pragmatic correlative equation applicable to grain design application was obtained. 1 2 3 4

Experimental Study of an N2O/Ethanol Propulsion System

Nitrous Oxide (N2O) / ethanol propulsion system is distinguished as the liquid propulsion with non-toxic, user-friendly, and storable bipropellant. The current target of the present study is to build a quick-response and maneuverable main engine of a sounding-rocket like flying test bed which will be applied to the hypersonic air-breathing propulsion researches in the near future. The application to the spacecraft propulsion is also considered due to its compatibility in lowtemperature operation environment. Two series of static firing tests were performed with 700 N class gas generator models so far. Current test results showed that valuable design data were collected and operational procedure was verified. Potential of application of composite materials to the combustion chamber was also examined from the chamber wall heat flux data obtained and the result of firing test using a thick SFRP chamber. Nomenclature

Solid Propulsion Systems for Epsilon Launch Vehicle

A new small solid launcher named Epsilon is currently under development in JAXA. The Epsilon launch vehicle is normally three stage rocket system and can be added an optional liquid propulsion system to the third stage for the missions requiring precision orbit insertion. The SRB-A motor boosting the H-IIA vehicle and the H-IIB vehicle will be shared as the first stage motor. Upper-stage motors are inherited from the fifth M-V launch vehicle, from the viewpoints of development cost reduction, performance increase, and advanced technology succession. The solid motor side jet (SMSJ) system, which is used for the roll control during the first stage powered flight and the three-axis control after the SRB-A burnout, will be newly developed based on the technology of the SMSJ for the M-V vehicle. A maiden flight of the first Epsilon is scheduled in the summer of 2013. A successive concept of the advanced propulsion technologies for next-gen Epsilon are also described in the present paper. There are many technical challenges, such as new propellants and mass reduction of nozzle liner, to be tackled with for the next couple of year.

A High-Speed Response LOX/LH 2 Full Expander Cycle Engine with Deep Throttling Capability

For a flight test campaign of reusable vehicle, 10 kN class small LOX/LH 2 propulsion systems have been developed. They are regenerative cooling engines with a continuous throttling capability for making vertical landing possible. Current phase of the campaign is to demonstrate an entire sequence of full-scale operation with a vehicle equipped with turbopump-fed engine, following the three-generation vehicles with pressure-fed engine had successfully performed in repeated flight operation tests between 1999 and 2003. From a result of primary system analysis, we decided to build an expander cycle engine by refurbishing a pair of turbopumps, which had been build for another research program, and putting them into a new engine developed in the present study. A combustion chamber with long cylindrical portion adapted to the engine cycle was also newly made. Three captive firing tests were conducted to verify functional suitability for the vertical landing flight. In the last two tests, a deep throttling capability down to 28 % and a high-speed response over 5 Hz of the propulsion system were successfully demonstrated with newly developed thrust control system. The fourth-generation vehicle powered by the full expander cycle engine is now under development.