국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	HIGH-ANGLE-OF-ATTACK YAWING MOMENT ASYMMETRY OF THE X-31 AIRCRAFT FROM FLIGHT TEST
저자	Brent R. Cobleigh
Keyword	Asymmetries; Forebody; High angle of attack; Noseboom; Reynolds number; Strakes; Tactical utility; Transition strips; X-31; Yawing moment
URL	http://www.dfrc.nasa.gov/DTRS/1994/PDF/H-2015.pdf
보고서번호	NASA-CR-186030
발행년도	1994
출처	NASA Dryden Flight Research Center
ABSTRACT	Significant yawing moment asymmetries were encountered during the high-angle-of-attack envelope expansion of the two X-31 aircraft. These asymmetries led to position saturations of the thrust vector vanes and trailing-edge flaps during some of the dynamic stability axis rolling maneuvers at high angles of attack. This slowed the high-angle-of-attack envelope expansion and resulted in maneuver restrictions. Several aerodynamic modifications were made to the X-31 forebody with the goal of minimizing the asymmetry. A method for determining the yawing moment asymmetry from flight data was developed and an analysis of the various configuration changes completed. The baseline aircraft were found to have significant asymmetries above 45 deg-angle of attack with the largest asymmetry typically occurring around 60 deg-angle of attack. Applying symmetrical boundary-layer transition strips along the forebody sides increased the magnitude of the asymmetry and widened the angle-of-attack range over which the largest asymmetry acted. Installing longitudinal forebody strakes and rounding the sharp nose of the aircraft caused the yawing moment asymmetry magnitude to be reduced. The transition strips and strakes made the asymmetry characteristic of the aircraft more repeatable than the clean forebody configuration. Although no geometric differences between the aircraft were known, ship 2 consistently had larger yawing moment asymmetries than ship 1.