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NAL's research program for high-speed civil transport (HSCT) is introduced, in relation to a government report 1) titled “National Long-term Research and Development Plan for Aeronautical Technology”. A guideline and a program 2) were proposed by a research committee which was specially organized in the Science and Technology Agency, so as to plan technology verification flight experiments with small high-speed experimental aircraft. Parallel to and in accordance with discussions by the committee, NAL established the concept of flight experiment and placed orders with aircraft manufacturers for three conceptual designs of unmanned supersonic experimental aircraft. The results of conceptual design studies are reported here.

The basic concept of unmanned aerial vehicle (UAV) powered by microwave is defined first by specially developed CAD software. Tele-communication relay or earth observation platform is its possible application. Some preliminary research programs including propeller efficiency, electric power plant, basic structural concepts and material testings are undergoing at NAL. The present paper demonstrates the results of a structural concept study and early strength characterization at room and low(= -60 °C) temperature points for a system of CF/thermoplastic composite as one of candidate material of main structures. The concerned strength drop due to a wide difference of the low temperature environment from the processing point of CF/PEEK can not be observed.

Since 1987, the NAL Tokyo has conducted the system definition study and some components tests to investigate the feasibility of 2 types of unmanned aerial vehicles; Microwave-Powered Unmanned Aerial Vehicle (MPUAV) for communication relay utilizations, and Chemical Energy Powered Unmanned Aerial Vehicle (CEPUAV), with very long range capability for the earth observation utilizations. Here MPUAVs which also need chemical energy in climbing phase are described. The research on energy transmission by microwave has conducted in some universities, CRL (Communications Research Laboratory) and industries, in both transmitting and receiving technologies. With the extensive use of a simple CAD program for MPUAVs, a configuration of 400kg all up mass and a 30m wing span is proposed, under the tentatively supposed specifications of microwave transmitted DC power supply. A scenario to develop and verify necessary technologies by scale model flight tests at low altitude is proposed.