The Integrated Flight and Propulsion Control (IFPC) for a highly maneuverable aircraft and a fighter-class engine with pitch/yaw thrust vectoring is described. Of the two IFPC functions the aircraft maneuver control utilizes the thrust vectoring based on aerodynamic control surfaces/thrust vectoring control allocation specified by the Integrated Control Unit (ICU) of a FADEC (Full Authority Digital Electronic Control) system. On the other hand in the Performance Seeking Control (PSC) the ICU identifies engine's various characteristic changes, optimizes manipulated variables and finally adjusts engine control parameters in cooperation with the Engine Control Unit (ECU). It is shown by hardware-in-the-loop simulation that the thrust vectoring can enhance aircraft maneuverability/agility and that the PSC can improve engine performance parameters such as SFC (specific fuel consumption), thrust and gas temperature.
This study deals with orbital transfer of a tethered satellite system in equatorial plane through its tether length control. Since tether length variation generates diversely different pitching motion on an elliptic orbit, appropriately designed tether length profiles can give the satellites a desired velocity-vector-increment at a prescribed position in orbit. This paper proposes a procedure to get an adequate control input profile which attains the designated states at the final position by applying nonlinear control method. Also the procedure can directly cope with physical restrictions for the system, such as the maximum tether length or tether tension. The proposed procedure consists of three steps associated with control for its angular momentum of pitching motion, which finally leads to control of tether length, pitch angular rate, and pitch angle at the final position, respectively.
The performance of a two-dimensional Mach 1.64 external compression air intake is investigated by computational fluid dynamics. The intake model consists of a 10-degree wedge and a subsonic diffuser. The flow in and around the intake with different configurations of the slit at the diffuser entrance is calculated to examine the effect of the configurations for pressure recovery and stability of the shock system. The numerical results indicate that the natural bleed fairly improves the intake performance at subcritical operation: It improves the maximum pressure recovery and the tolerance of the mass flow rate through the diffuser to guarantee the stability of the shock. The bleed mass flow rate strongly depends on the slit configuration. Large bleed mass flow rate increases the tolerance of the diffuser mass flow rate for the shock stability. However, the presence of the slit provides no gain in efficiency of the intake at supercritical operation.
In the present study we have developed a numerical method to simulate the flight dynamics of a small flying body with unsteady motion, where both aerodynamics and flight dynamics are fully considered. A key point of this numerical code is to use computational fluid dynamics and computational flight dynamics at the same time, which is referred to as CFD2, or double CFDs, where several new ideas are adopted in the governing equations, the method to make each quantity nondimensional, and the coupling method between aerodynamics and flight dynamics. This numerical code can be applied to simulate the unsteady motion of small vehicles such as micro air vehicles (MAV). As a sample calculation, we take up Taketombo, or a bamboo dragonfly, and its free flight in the air is demonstrated. The eventual aim of this research is to virtually fly an aircraft with arbitrary motion to obtain aerodynamic and flight dynamic data, which cannot be taken in the conventional wind tunnel.
Nonlinear aeroelastic phenomena of two dimensional system in transonic regime was numerically analyzed. Unsteady aerodynamics excited by pitching and heaving oscillation was investigated based on the first harmonic component of the aerodynamics computed by Navier-Stokes code. It indicated nonlinearity existed not only in the oscillation with massive flow separation but also in small amplitude less than 0.5deg pitching oscillation. Stability analysis with first harmonic component of the unsteady aerodynamics brought a bifurcation diagram, which gave an estimation of the amplitude of Limit Cycle Oscillation (LCO). The estimated amplitude of LCO was confirmed by the numerical simulation. Nonlinearity of the unsteady aerodynamics in small amplitude, which affected stability boundary, had a high correlation with transition of boundary layer.
Rocket-shaped vehicle is developed to conduct microgravity experiment by dropping from the high-altitude balloon. Its design strategy and development status is introduced. Also, the result of its 2nd flight test is summarized to show the feasibility of the balloon-based microgravity experiment.