Tsuyoshi Yagishita

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

Combustion Characteristics of Hybrid Rocket Motor Using GAP as a Solid Fuel(II)

Hybrid rockets using Glycidyl Azide Polymer (GAP) as a solid fuel has been studied. Linear burning rate spectrum of GAP was spread with a dilution of polyethylene glycol (PEG), and basically, self combustible mixtures are used for the gas hybrid rocket motor, and non-self combustible mixtures for traditional hybrid motor. Ultrasonic measurement is employed using three sensors especially developed for this use to evaluate the instantaneous surface regression rates in the traditional hybrid motor. Results from three sensors set at the upstream, middle and downstream of 1.3m length motor give indispensable informations for the establishment of the flame model of hybrid motor.

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.

Development of a Reusable LOX/LH2 Rocket Engine - Firing Tests and Lifetime Evaluation Analysis

The main engine of the Reusable Sounding Rocket has been developed at the Kakuda Space Center of the Japan Aerospace Exploration Agency. A total of 54 engine firing experiments were conducted between June 2014 and February 2015. Throughout these experiments, advanced capabilities and functions of this engine, such as wide range throttling, accurate controllability, and health monitoring, were proved to be feasible. This rocket is also required to be reusable for over 100 flights. To confirm the long-life durability of this engine for over 100 flights in a limited experiment period, sequential multiple-firing tests were planned and conducted. Numerical analysis to evaluate damage of the main chamber due to firings was also conducted. The results of durability tests and numerical analysis showed reuse of this engine for over 100 flights to be feasible.