INTRODUCTION

The increased concern with airplane characteristics at high angles of attack during stall, departure, and spin has motivated research in this angle of attack regime. There is a lack of complete confidence in the ability of current design methods to predict airplane handling qualities at high angles of attack, so experimental as well as analytical data are needed. The prediction of the handling qualities of an airplane relies to a large extent on the prediction of its stability and control characteristics. The proof of a new design must await flight tests, when the measured airplane stability and control characteristics can be compared with those estimated before flight test. The design cycle is reasonably well understood for low speeds and angles of attack for normal maneuvering, but the desire to utilize high angles of attack has expanded design envelopes beyond previously accepted design limits.

In response to the interest in stall, departure, and spin controllability, the NASA Flight Research Center is flight testing an unpowered remotely piloted 3/8-scale model of the F-15 airplane to high angles of attack. The remotely piloted flight test technique (ref. 1) was chosen because of the risks involved in aircraft spin testing. The technique is versatile in that the pilot interacts with the vehicle as he does during normal flight, it is potentially more economical than full-scale flight testing, and it allows the flight envelope to be expanded more rapidly than do conventional flight test methods. The derivative characteristics determined during the flight program were used both to verify the predicted airplane model aerodynamics and to update a flight support simulator.

This report documents the stability and control derivatives of the F-15 airplane model determined at subsonic speeds over an angle of attack range from - 20⁰ to 53⁰.