Low speed wind tunnel tests were conducted to understand the aerodynamic interferences caused by the engine exhausted jet on an SST configuration where the engine was mounted over the fuselage. The take-off and landing flight conditions with power-on were simulated by the jet flow exhaust from the engine nozzle. The aerodynamic interferences were investigated at several nozzle pressure ratios, model attitudes, and tail geometries. It was observed that the flow around the engine nozzle was accelerated by the exhausting jet, and this resulted in significant interferences on aerodynamics. The interference was strongly influenced by the airframe geometry near the engine nozzle.
This paper addresses fold lines induced by a wrapping fold of a large space membrane to realize the high packaging efficiency. Details of the fold lines are examined by performing wrapping fold experiments. The experimental results indicate that the fold line induced by the wrapping fold deviates from the target fold line, and the deviation of the fold line decreases the packaging efficiency. The configuration of the induced fold line is identified analytically, where the deformation of the crease induced by the wrapping fold is considered. The relationships between the configuration of the induced fold line and the mechanical parameter of the wrapping fold, which are the tensile force and the bending stiffness, are determined by the theoretical analysis. The relationships are verified by comparing with the experimental results. Based on the fold line obtained by the theoretical analysis, a fold pattern is proposed to avoid the deviation of the fold line. Finally, the high packaging efficiency is realized by using the proposed fold pattern.
Experiment using the 2m× 2m transonic wind tunnel in JAXA and numerical simulation based on the RANS are carried out to investigate transonic flowfield influenced by a protuberance attached to shoulder of a generic cone-cylinder type rocket faring. Thickness of the protuberance considered here is about 0.1% of the fairing diameter, which is 1.8 times thicker than the displacement thickness of the incoming boundary layer. Validation and verification of the numerical method are firstly performed based on the experimental result of the clean fairing without any protuberance. It is found that effect of the protuberance changes depending on the flow speed. If the free-stream Mach number is less than 0.8, separation shock wave is generated at the protuberance on the shoulder, although the separation shock wave appears at the cylinder section of the clean fairing. On the other hand, little influence on the flow structure is observed in the flow condition with higher free-stream Mach number. The effect revealed in this study indicates the importance of the protuberance to the design of rocket fairing.
This paper is concerned with the flight controller design of Quad Tilt Wing (QTW) Unmanned Aerial Vehicle (UAV) which has Vertical Take-Off and Landing (VTOL) capability as well as high speed cruise performance. The flight controller is composed of Stability Augmentation System (SAS), which feedbacks angular velocity, and Control Augmentation System (CAS), which feedbacks the difference between attitude commands and current attitude angles. The gains of S/CAS are both scheduled by the tilt angle of the main wings of the QTWUAV since its airspeed and flight dynamics drastically change in accordance with the tilt angle. The S/CAS are designed by three steps; we first select several design points, then design the controller gains at those design points, and finally connect the gains by linear interpolation. In the design process of the controller gains, perturbed models are introduced in addition to the nominal models, and common gains for those models are designed to ensure robust control performance against modeling errors. Full transition flight from vertical take-off to horizontal cruise was successfully accomplished using our controllers.