Control Power Criteria for Statically Unstable Aircraft.
Abstract
The sensitivity of control power requirements during gust response to variations in aircraft parameters and input disturbance levels has been investigated in an attempt to provide data useful in establishing design criteria and margins of safety needed in the control of aerodynamically unstable aircraft. Both canard configured and a conventional tail configured aircraft were used in this study. For both configurations the critical flight conditions were during the low-speed power approach. The critical gust frequency in terms of critical power requirement for a (1-cos) type gust was approximately twice the closed loop natural frequency of the aircraft. Static margin was found to be the primary quantity influencing the control power requirements. The sensitivity of required control power to variation in other aircraft parameters is predictable by the manner in which these parametric variations alter the static margin. The high angle of attack characteristics also had a significant effect on the control power requirements - indicating the need for a complete and accurate data base in this region. The gust upset boundaries dropped off sharply when the discrete gust was applied at a significant angle from the vertical. The control power requirements were found to be relatively insensitive to variations in the discrete gust mode shape in the absence of control surface rate saturation. Likewise, the increases in required control power due to increased gust magnitude were also relatively small when the surfaces were not rate saturated. When rate limits were reached, however, discrete gust magnitude and shape became more significant and those gust shapes that caused the longest periods of rate saturation were most critical.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1976
- Accession Number
- ADA033969
Entities
Organizations
- General Dynamics