A modified output error method was developed by the authors, the application of which on YF16 aircraft have been reported in our previous paper. In this paper, we applied the method on ALFLEX (Automatic Landing Flight Experiment) flight data supplied by NAL/NASDA for estimating the aerodynamic characteristics and the input control histories. The results show that, the time histories of the altitude, the total velocity, Euler angles are very precisely estimated like our previous applications. Then, we have tried to verify the performance in more detail, particularly for high frequency characteristics. The applied data include the effect of intentional control surfaces vibration inputs. The result shows that the method is also effective to these high frequency variations.
ETS–VII is a test satellite to perform in-orbit demonstration of autonomous rendezvous docking (RVD) technology, which will be necessary for advanced space activities in the early 21st century. ETS–VII performed three RVD experiment flights, and verified all technical items. ETS–VII demonstrated first autonomous RVD between unmanned vehicles, and remote piloted rendezvous flight position accuracy at docking was about 1cm, and acceleration was less than 1.5mG (low impact docking). In the second RVD experiment flight, ETS–VII detected attitude anomaly and executed disable abort for safety insurance. We present the results and evaluation of three RVD experiment flights in this paper.
In order to carry heavier payloads and to fly longer distance, the compact engine is required. The ram combustor with the double-staged flameholders was introduced to shorten the ram combustor which is a major component of the ATR. An additional flamefolder is placed downstream of the conventional (single-staged) one to achieve quick flame expansion in the downstream direction. The ram combustion test was carried out in a 120 deg sector chamber for three cases of flameholder configuration to investigate the various effects on the combustion and aerodynamic performances. The ram combustor with the double-staged flameholders increased the combustion efficiency without large total pressure loss and therefore it was able to shorten 40% axial length of the ram combustor in comparison with the ram combustor with a conventional flameholder. In this study, for the compact ram combustor, the combustion efficiency is greater than 80% on sea level static condition where the air temperature and pressure at the combustor inlet is much lower than that of the supersonic flight condition.
We propose the concept of Tethered Satellite Cluster Systems. The system consists of the satellites connected by tethers, and keeps and changes the formation with active tension/length control of the tether. The purpose of the system is the saving of the thruster fuel required for the coordinated mission and the improvement of the control precision, using tether tension. The system is applied to tethered service satellites, which perform the missions, for example an autonomic inspection, casting, capture, moorage and deorbit of an uncontrolled satellite. In this paper, we treat the rotating motion; satellites rotate on the center of the mass of the system with the formation in same plane. We establish the coordinated control method using tension and thrust. This control method can decrease the fuel consumption of the thruster, for utilizing the tether tension/torque equilibriums. It can also improve the control precision. Moreover, we establish the formation control method without thrust for the transition to the objective formation.
Rendezvous docking technology will be necessary for advanced space activities in the early 21st century, such as logistic support service to the International Space Station, exchange of observation sensors or bus equipments, re-supply of fuel or cryogenic liquid, etc. A chaser vehicle will perform rendezvous along a reference trajectory, which would be pre-planned and well investigated. If the chaser deviate from the reference trajectory for instance because of thruster trouble, it will be required to recover to the reference trajectory as soon as possible. In this paper, we introduce an easy and practical recovery method based on C–W solution of Hill’s equation. We think the recovery method will be applicable for many kinds of rendezvous vehicles.
This paper presents a computational parametric study showing how heat release affects aerodynamic characteristics, drag and heating rate, of a hypersonic flow over an axisymmetric blunt body. A chemical non-equilibrium viscous flow is assumed together with seven chemical species and finite-rate chemical reactions. Results show that heat release in the upstream of the body can reduce not only the aerodynamic drag but also the aerodynamic heating rate on the body. Three parameters which control heat release are introduced and their effects on the flow structure, especially on the drag and the heating rate, are presented. It is shown that the drag is reduced to 23% of the baseline value (the drag of the flow without heat release) and the aerodynamic heating rate to 76%.