New device for controlling asymmetric flowfields on forebodies at large alpha

An exploratory experimental investigation of a new device to control the asymmetric flowfield on forebodies at large angles of attack has been conducted. The device is a rotatable forebody tip, which varies in cross section from circular at its base to elliptic at its tip. The device itself extends over a small portion of the aircraft or missile forebody. The device provides two important improvements. First, it replaces the normally random behavior of the nose side force as a function of nose tip orientation with a predictable and generally sinusoidal distribution; second, the device shows promise for use as part of a vehicle control system to be deflected in a prescribed manner to provide additional directional control for the vehicle. The device was tested on a cone/cylinder model having a 10-deg semiapex angle and on a 3.0-caliber tangent ogive model. Data were taken with each model at a Reynolds number of 8.4 x 10 4 based on cylinder diameter and by a helium-bubble flow visualization technique at a Reynolds number of 2.4 x 10 4.