Global InformationRelaxed stability information
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In aviation, an aircraft is said to have relaxed stability if it has low or negative stability.[1][2]
An aircraft with negative stability will have a tendency to change its pitch and bank angles spontaneously. An aircraft with negative stability cannot be trimmed to maintain a certain attitude, and will, when disturbed in pitch or roll, continue to pitch or roll in the direction of the disturbance at an ever-increasing rate.
This can be contrasted with the behaviour of an aircraft with positive stability, which can be trimmed to fly at a certain attitude, which it will continue to maintain in the absence of control input, and, if perturbed, will oscillate in simple harmonic motion on a decreasing scale around, and eventually return to, the trimmed attitude.[citation needed] A positively stable aircraft will also resist any bank movement. A Cessna 152 is an example of a stable aircraft. Similarly, an aircraft with neutral stability will not return to its original attitude without control input, but will continue to roll or pitch at a steady (neither increasing nor decreasing) rate.[citation needed]
- ^ Nguyen, L. T.; Ogburn, M. E.; Gilbert, W. P.; Kibler, K. S.; Brown, P. W.; Deal, P. L. (1 December 1979). "Simulator study of stall/post-stall characteristics of a fighter airplane with relaxed longitudinal static stability. NASA Technical Paper 1538". NASA Technical Publications (19800005879). NASA: 1. Retrieved 6 July 2022.
- ^ Wilhelm, Knut; Schafranek, Dieter (October 1986). "Landing approach handling qualities of transport aircraft with relaxed static stability". Journal of Aircraft. 23 (10): 756–762. doi:10.2514/3.45377. ISSN 0021-8669. Retrieved 6 July 2022.