Two solid rocket boosters provide the primary first stage thrust for the H-ll rocket, each producing a thrust of 1570 KN (160 tonf) at sea level. At the present time, about four years prior to the first launch, most of the booster sub-systems are either undergoing qualification or have already been qualified. A first full duration static firing test was conducted successfully on this April 15, 1988. This paper describes the present status of the design and development of the H-II rocket solid Rocket booster.

View full abstract

As known well, the expander cycle is advantageous in performance and reliability, but some limitations come from increasing chamber pressure and/or thrust. They are dominated inherently by the thermal energy absorbed by the regenerative coolant to drive the turbopump. In order to improve this problem to some extent, we have proposed the advanced concept thrust chamber in which an additional heat exchanger was installed to extract the larger amount of thermal energy from combustion (ref. 1). We have applied this concept for the LOX/LH₂ high pressure expander cycle engine that is designated as HIPEX engine. Preliminary tests using a sub-scale engine made it clear that the combustion performance was not affected by installation of a heat exchanger within a combustion chamber, and the heat flux averaged over heat exchanger became approximately 70 percent of the value evaluated by Bartz’s correlation. In addition, wide thrust throttling (down to 23 percent of rated value) and restart capabilities were also verified. These test results revealed that the HIPEX engine delivering 140 kN of thrust at 10 MPa of chamber pressure is feasible. This paper describes the features of the HIPEX engine and the preliminary tests using the sub-scale engine.

View full abstract

The Electro-thermal Hydrazine Thruster (EHT) is promising in points of weight and cost as a thruster for north-south station keeping in geosynchronous satellite. The immersion heating type EHT under development is remarkable in its high heat efficiency but has a disadvantage of being exposed directly to decomposed hydrazine gas so that the heater is required to have such characteristics as decomposed hydrazine gasproof, anti-sagging, vibration-proof and highly efficient heat exchangeability. Thus, we conducted basic experiments on various characteristics with the material and coil form as parameters. The results are that the doped tungsten is preferable and each characteristic can be quantified from coil geometrical parameters. The heater designed on the basis of these experiments’ results fulfilled the required basic performance of EHT.

View full abstract

Difficulties to reach a high altitude is inherent for small rockets. But, several heuristic approaches have made it possible to climb an altitude of about 100 km by a small rocket of which mass is less than 50kg. Basic idea behind those approaches are explained with an analytical description how difficult it is to climb a high altitude for small rockets. Among them, an approach by optimum thrust programming is discussed rather in detail in connection with the so called Goddard problem.

View full abstract