To improve the aerodynamic performance at take-off and landing flight and coexist with the natural laminar flow wing geometry, the capability of the Krueger flap and its flow mechanism were investigated on a JAXA-QSST configuration. Parametric studies using numerical analysis are conducted on variation of the mutual locations between Krueger flap and main wing, and the flap deflection angles. The lift-to-drag ratio characteristics are strongly influenced by the mutual locations and deflection angles by effectively controlling the vortex flow over the flaps and main wing. Comparing with the conventional leading-edge flaps, higher lift-to-drag ratio is obtained by the Krueger flap. Because, the vortex lift at the flap and suppression of flow separation at main wing improve the lift-to-drag ratio by the Krueger flap deploying.
We applied the LPV (Linear Parameter-Varying) control theory to attitude control for spacecraft. With this method, control stability and control performance can be considered at the same time. This method was applied to attitude tracking problems. In this paper, a method to apply the LPV control theory to the tracking problem of the attitude as well as the angular velocity. We focus on spacecraft with multiple RWs (Reaction Wheels). Using the redundancy, an unloading method for the RWs is also described. Numerical simulations assumed a spacecraft with four RWs are conducted to compare the tracking error by the proposed method and by a Lyapunov-based control.
To realize the space planes, there is a need for a system analysis considering the trajectory and airframe design at the same time. In this study, for applications to airframe design applying a waverider which has high performance at hypersonic region, it was carried out design and trajectory optimization at the same time. As a specific mission, we designed the booster to accelerate the orbiter of 45ton to transport a payload of 0.8ton to LEO to Mach 12. As the result, we obtained booster the weight of 442ton. The result showed that it was important to consider about the small thrust in trajectory and trim balance when airframe design was performed.
For a self-field magnetoplasmadynamic (MPD) thruster using hydrogen propellant, plasma flows were numerically simulated with a model including the ion-slip effect. To clarify the thruster behavior near the critical current, the discharge current and the propellant mass flow rate were set to 5 or 10 kA (critical current) and 0.4 g/s, respectively. At the critical current, current paths protruded toward a downstream region due to an increased Hall parameter when compared with the lower current case. In conjunction with this, the pressure was higher in the vicinity of the cathode tip and the ion-slip parameter exceeded unity in the discharge chamber at the critical current. Significant ion-slip heating occurred in the supersonic region, which resulted in limited amount of gas dynamic thrust.
The magnetic suspension and balance system (MSBS) suspends a model without physical support systems. With the use of a pair of two-dimensional CMOS image sensors, a position sensing system that detects the position of the model by dynamically tracking the model attitude was developed with the aim of applying an MSBS for high angles of attack (AOAs). The position sensing system developed in this study was able to detect the position and attitude of the model within the range of AOAs of -40 to 40 degrees. The position sensing system was installed to an existing 60 cm MSBS at JAXA, and static and dynamic wind tunnel tests were conducted to investigate the ability of the MSBS and the dynamic characteristics of a delta wing aircraft model at various AOAs. The MSBS could suspend and oscillate the model in pitch direction at AOA of 15 degrees with the amplitude of 6 degrees in the wind. The delta wing model was dynamically stable at each tested AOAs.
The suitable fuel for reduced-toxicity hypergolic bipropellant has been explored in this study. High concentration of hydrogen peroxide and sodium borohydride were used as an oxidizer and a fuel additive for ignition source. Fuel candidates were narrowed down by many requirements such as toxicity, chemical regulation, storability, cost, specific impulse, solubility of additive and ignition delay. As a result, 3-methylaminopropylamine (MAPA) was selected as the best fuel for reduced-toxicity bipropellant. MAPA doped with sodium borohydride showed very fast hypergolicity with hydrogen peroxide and its ignition delay time was less than 10msec. MAPA and hydrogen peroxide bipropellant can achieve 98.3% of theoretical specific impulse of MMH/NTO, whereas MAPA has low toxicity compared with MMH.