|M.Sc Student||Birarov Ofer|
|Subject||Reducing Miss Distance by Using Twisting Wing|
|Department||Department of Aerospace Engineering||Supervisors||PROF. Yoseph Ben-Asher|
|PROF. George Hexner|
|Full Thesis text - in Hebrew|
The purpose of this study is to present a new method for controlling a missile's flight path. The method relies on the twisting of a high aspect ratio wing to obtain the lift required to alter the missile's flight path. Because the flight control is affected by direct lift, very short response times are obtained. This in turn enables the achievement of surprisingly small miss distances.
The missile is guided by twisting its wings. The tail serves as a stabilizer only and does not move. The root of the wing are attached rigidly to the fuselage, and are twisted by small servos. The wing twist is zero near the root of the wing and increases linearly to the wing tip. This in turn causes the maximum lift to be produced near the wing tip. The resulting distribution of lift minimizes the induced flow impinging on the tail surfaces, which in turn results in minimal induced roll moment.
The advantage of this method of flight control is that lift is produced as soon as the servo twists the wing. The resulting missile acceleration time constant is about equal to the servo time constant.
The study compares the performance of the missile using the wing twist method of piloting with the performance of a missile which is piloted conventionally by deflecting the rear fin.
Twisting the missile's wing develops the aerodynamic force near the missile center of gravity so that the missile angular dynamics are little affected by the deflection of the control surface. Even though the conventionally controlled missile exhibited improved response due to the autopilot, its response remained inferior to that of the missile piloted by wing twisting.
To compare the miss distances achievable using the two piloting methods a simple simulation was implemented. The performance of the two missiles were compared in two scenarios. Miss distances due to an initial heading error and miss distance due to step in target acceleration.
The results of the miss distance study demonstrate the superiority of the missile piloted by wing twisting. It was found that the miss distance was nearly zero down to time to go approximately equal one second time to go, the miss distance due to a step acceleration of the target showed even bigger performance differences. The miss distance for the wing controlled missile was less than one tenth of the miss distance obtained for the tail controlled missile.