A Wind Tunnel Investigation to Determine Dominant Forebody Strake Design Characteristics for an F-15 Equipped with Conformal Fuel Tanks.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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A parametric study was made in the AFIT 5-ft wind tunnel of forebody strakes on an F-15C model equipped with conformal fuel tanks. Parameters of interest were strake planform area and strake angle of incidence. Twenty configurations were evaluated for longitudinal and lateral stability at angles of attack from -4 to 46 deg. Lift coefficient, drag coefficient, and pitching moment coefficient CM were plotted angle of attack alpha. Data indicated that an excessive positive increase in the derivative of CMderivative of alpha can be expected at angles of attack of 20 deg or less. Above 20 deg, CM may be tailored by varying the strake area and incidence angle. For each strake examined, and angle of incidence of either -3 or -6 deg depending on planform area produced a more nearly linear CM vs alpha curve than 0 degrees therefore, incidence angle should be considered in strake design optimization. Lateral stability data were taken on 12 configurations from 16 to 44 deg angle of attack. To determine spin susceptibility, the parameter for predicting lateral-directional stability was plotted for the most promising configurations. Very little constructive change in lateral stability was noted for the configurations tested.
- Attack and Fighter Aircraft