Forebody Aerodynamics of the F-18 High Alpha Research Vehicle with Actuated Forebody Strakes

Extensive pressure measurements and off-surface flow visualization were obtained on the forebody and strakes of the NASA F-18 High Alpha Research Vehicle (HARV) equipped with actuated forebody strakes. Forebody yawing moments were obtained by integrating the circumferential pressures on the forebody and strakes. Results show that large yawing moments can be generated with forebody strakes. At a 50 deg-angle-of-attack, deflecting one strake at a time resulted in a forebody yawing moment control reversal for small strake deflection angles. However, deflecting the strakes differentially about a 20 deg symmetric strake deployment eliminated the control reversal and produced a near linear variation of forebody yawing moment with differential strake deflection. At an angle of attack of 50 deg and for 0 deg and 20 deg symmetric strake deployments, a larger forebody yawing moment was generated by the forward fuselage (between the radome and the apex of the leading-edge extensions) than on the radome where the actuated forebody strakes were located. Cutouts on the flight vehicle strakes that were not on the wind tunnel models are believed to be responsible for deficits in the suction peaks on the flight radome pressure distributions and differences in the forebody yawing moments.

[1]  R. S. Eliot.  Lessons Learned and Future Directions , 2020, Responsibility of Higher Education Systems.

[2]  Stephen A. Whitmore,et al.  A preliminary look at techniques used to obtain airdata from flight at high angles of attack , 1990 .

[3]  Wendy R. Lanser,et al.  Wind tunnel measurements on a full-scale F/A-18 with forebody slot blowing or forebody strakes , 1993 .

[4]  Larry A. Meyn,et al.  Forebody flow control on a full-scale F/A-18 aircraft , 1992 .

[5]  David F. Fisher,et al.  Flight and full-scale wind-tunnel comparison of pressure distributions from an F-18 aircraft at high angles of attack. [Conducted in NASA Ames Research Center's 80 by 120 ft wind tunnel] , 1994 .

[6]  David F. Fisher,et al.  Controlling forebody asymmetries in flight: Experience with boundary layer transition strips , 1994 .

[7]  Stephen A. Whitmore,et al.  The effects of pressure sensor acoustics on airdata derived from a high-angle-of-attack flush airdata sensing (HI-FADS) system , 1991 .

[8]  C Asbury Scott,et al.  Multiaxis Thrust-Vectoring Characteristics of a Model Representative of the F-18 High-Alpha Research Vehicle at Angles of Attack From 0 to 70 , 1995 .

[9]  David F. Fisher,et al.  Effect of Actuated Forebody Strakes on the Forebody Aerodynamics of the NASA F-18 HARV , 1996 .

[10]  Gautam H. Shah,et al.  AIAA 93-3675 CP Actuated Forebody Strake Controls for the F-18 High-Alpha Research Vehicle , 1995 .

[11]  Lawrence A. Walchli.  Flight evaluation of pneumatic forebody vortex control in post-stall flight , 1994 .

[12]  David M. Richwine,et al.  In-Flight Flow Visualization Characteristics of the NASA F-18 High Alpha Research Vehicle at High Angles of Attack , 1989 .

[13]  Joseph W. Pahle,et al.  Thrust Vectoring on the NASA F-18 High Alpha Research Vehicle , 1996 .

[14]  R. E. Curry,et al.  An airborne system for vortex flow visualization on the F-18 high-alpha research vehicle , 1988 .

[15]  Daniel W. Banks,et al.  F-18 high alpha research vehicle surface pressures: Initial in-flight results and correlation with flow visualization and wind-tunnel data , 1990 .

[16]  Daniel G. Murri,et al.  Exploratory studies of actuated forebody strakes for yaw control at high angles of attack , 1987 .

[17]  Joseph W. Pahle,et al.  An Overview of Controls and Flying Qualities Technology on the F/A-18 High Alpha Research Vehicle , 1996 .