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Downsizing the engine would be an effective means of improving fuel economy and reducing CO2 emissions. In this case, low-speed torque generation can be enhanced through the use of impulse charging technology, a subject attracting the attention of many researchers. This paper reports the basic characteristics of impulse charging identified through research using a single-cylinder test engine, aiming for application of the technology to spark ignition (SI) engines. To ensure the maximum level of volumetric efficiency under impulse charging conditions, two requirements are controlling the timing of switching from a negative to a positive pressure wave while turning its direction at the intake chamber, and maximizing the positive pressure wave.

“ASKA” developed by National Aerospace Laboratory (NAL) is a quiet, short take-off and landing (QSTOL) research aircraft adopting upper surface blowing (USB) concept as a powered high lift system. To achieving sufficient STOL performance by augmenting stall angle of attack and roll control power, blowing BLC technique was applied to the outboard leading edges and ailerons.Supplied high pressure air to save the BLC piping space,the BLC system which was fit for use of high pressure air was developed. The BLC system, in which BLC air is discharged by a series of discrete jets from small drilled holes (0.8 ∼ 3.0 mm in diameter) arranged in a raw, is one of the unique features of the aircraft. In this paper, the summaries of aerodynamic development of the BLC system are described except for the air piping system.

The ASUKA was based upon the airframe of the home produced C-1 tactical transport which was modified into an Upper Surface Blowing (USB) powered high lift STOL aircraft. But the wing configuration was not changed. Therefore, this Experimental Aircraft doesn't always have the optimum configuration of a USB type aircraft. This paper describes the investigations which have been conducted to improve the aerodynamic characteristics of a subsonic jet transport semi-span model with an Upper Surface Blowing Flap system which has been newly designed using the NAL STOL-CAD program. The tests were conducted in the NAL 2- by 2-meter Gust Wind Tunnel and results were obtained for several flap and slat deflections at engine thrust coefficients from 0 to 1.85. As compared with the aerodynamic characteristics of the ASUKA model, we obtained the possibility of reduction of the airframe weight and significant improvement of the aerodynamic characteristics.