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Desirable flight styles and techniques in ski jumping were calculated on the basis of the new aerodynamic force data for three styles: classic style, V style, and flat V style. In the V style and flat V style two skis are in a herringbone position in the frontal plane, whereas in the classic style the skis are parallel Flat V style is more flat in the sagittal plane than V Style. The most effective style was the flat V style if a ski jumper model did not change style during the gliding phase, which was the late part of flight phase (distance was 110 m). If the model changed flight style, the model that changed from classic style to V style at 1.3 s after takeoff or from flat V style to V style at 1.6 s could achieve 112.5 m. In addition, forward initial angular velocity was a positive factor to increase distance; in particular, the distance for the V style was sensitive to initial angular velocity.

A low-sonic-boom design method is developed by combining a three-dimensional Euler computational uid dynamics code with a least-squares optimization technique. In this design method, the fuselage geometry of an aircraft is modi ed to minimize the pressure discrepancies between a target low-boom pressure signature and a calculated signature. The aircraft con gurations that generate three types of low-boom pressure signatures, i.e., attop type, ramp type, and hybrid type, are successfully designed by this method. It is shown that the sonic-boom intensity of the aircraft designed by linear theory is reduced and the attop-type ground pressure signature is obtained by this method. The results of the study suggest that this method is a useful tool for low-boom design. NomenclatureA e = equivalent-area distribution of aircraft C D p = pressure drag coef cient C L = lift coef cient F.¿ / = F function H = normal distance from aircraft J = object function in optimization process K = number of design variables used in optimization process L = aircraft length M = freestream Mach number P b= baseline pressure in optimization process P t = target pressure in optimization process p 1 = freestream static pressure x = streamwise location y = spanwise location = p M 2 ¡ 1°= speci c heat ratio 1p = shock overpressure 1S = element length of pressure signature 1T R = rise time of shock overpressure ± k = kth design variable Subscript i = i th element of pressure signature in optimization process

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