researching and developing original launch vehicles with this goal. These developments are summarized in Table 8.8. Of the concepts in this table both MOLNIYA and HOTOL plan to use existing transportation systems to gain sufficient altitude and velocity for air-breathing to function. SANGER is a new hypersonic vehicle under development which will jettison its ramjet when the atmosphere becomes too sparse for effective operation and revert to conventional rocket engines. X- 30 and SSTO/NAL are conceived as single stage Spaceplanes. As MOLNIYA and HOTOL are launched in the air, they have an advantage from the view point of risk analysis during development. A two stage Spaceplane like SANGER is at first sight a feasible concept. With increases in fuel efficiency due to the air breathing engine and reductions in system weight due to use of advanced materials and structural design, it will realize more in the long term. But there are a lot of problems with it as the next generation transportation system. These are 1. The need to develop two types of transportation (Booster, Orbiter) 2. The problem of vehicle separation at supersonic velocity 3. Due to the utilization of horizontal take-off, it is difficult to plan for emergencies, both in terms of emergency infrastructure and possible crash sites. This is also a serious problem for X-30 and SSTO. system studies for Spaceplanes are being developed based on the use of air-breathing engines both at The best solution appears to be reusable, horizontal take-off and landing Spaceplanes. All aspects of research, from studies of aerodynamics, structure, materials, flight control, numerical simulation to NASP office in the United States and NAL in Japan. Spaceplane - A Reusable Winged Single Stage to Orbit The Spaceplane concept is designed to support a new generation of manned spaceflight. Spaceplanes must emphasize safety, reliability and crew comfort and have unrestricted access for international use. One of the main purposes of Spaceplane development is to reduce launch costs due to reusability of the launcher. The characteristics of Spaceplanes - reusability, horizontal take-off and landing and air-breathing engine technology - have not yet been tested in space transportation systems. Research in this area, however, suggests that air-breathing technology could be critical in making spaceflight earlier in the 21st Century. ________________________ Table 8.8 Space Planes ___________ ___________ MOLNIYA HOTOL SANGER X-30 SSTO/NAL Main projector / planner MOLNIYA (Russia) BAe (UK) MBB (Germany) NASP (the United States) National Aerospace Laboratory (Japan) Purpose of development Reduce cost of launch and use spacecraft freely Reduce cost of launch by 1/5 and use spacecraft freely To transport materials and persons safely from Europe and reduce cost of launch by 1/10-1/5 and establish the technology of supersonic flight Establish SCRAMjet engine in order to realize the system of reusable single stage Spaceplane Establish safe and comfortable manned transportation system Total length (m) 18.2 (Assumption) about 52 83 / 28 (lower stage / upper stage) 46-61 94
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