Care-Free Maneuverability At High Angle of Attack

Joseph R. Chambers

Since the airplane’s earliest days, maintaining safe flight at low speeds and high angles of attack has been a stimulus for research. As well, ensuring that a military fighter aircraft has good high-angle-of-attack qualities can benefit its combat capabilities. NASA research has pro­vided critical guidance on configuration effects and helped usher in the advent of powerful flight control concepts.

T THE TIME THAT the National Aeronautics and Space Administration (NASA) absorbed the National Advisory Committee for Aeronautics (NACA), it also inherited one of the more challenging technical issues of the NACA mission: to "supervise and direct the scientific study of the problems of flight with a view to their practical solution.” Since the earliest days of heavier-than-air flight, intentional or inadvertent flight at high angles of attack (high alpha) results in the onset of flow separation on lifting surfaces, stabilizing fins, and aerodynamic controls. In such conditions, a poorly designed air­craft will exhibit a marked deterioration in stability, control, and flying qualities, which may abruptly cause loss of control, spin entry, and cat­astrophic impact with the ground.[1273] Stalling and spinning have been— and will continue to be—major areas of research and development for civil and military aircraft. In the case of highly maneuverable military aircraft, high-angle-of-attack characteristics exert a tremendous influ­ence on tactical effectiveness, maneuver options, and safety.

Some of the more notable contributions of NASA to the Nation’s military aircraft community have been directed at high-angle-of-attack technology, including the conception, development, and validation of advanced ground – and flight-test facilities; advances in related disci­plinary fields, such as aerodynamics and flight dynamics; generation
of high-alpha design criteria and methods; and active participation in aircraft development programs.[1274] Applications of these NASA contribu­tions by the industry and the Department of Defense (DOD) have led to a dramatic improvement in high-angle-of-attack behavior and asso­ciated maneuverability for the current U. S. military fleet. The scope of NASA activities in this area includes ground-based and flight research at all of its aeronautical field centers. The close association of NASA, industry, and DOD, and the significant advances in the state of the art that have resulted from common objectives, are notable achievements of the Agency’s value to the Nation’s aeronautical achievements.