This standard developed the lateral control divergence parameter. It also defines the closed-loop requirements for aircraft. These requirements are based on a 4th-order transfer function of the closed-loop dynamics. Therefore any aircraft model must be reduced to an equivalent 4th-order model for compliance testing. It specifies the frequency and damping requirements for dutch-roll modes as well as the time to 30 deg bank angle with full lateral stick input. This last requirement was tested with non-linear simulation time history data. Response bandwidth is tested with high-order linear models. This specification requires that the aircraft have speed stability through a positive stick gradient, although this is satisfied if the flight control system can provide the same speed stability response.[^3] The total time delay between the pilot and aircraft should be less than 0.1 s. In this standard all nonlinearities are required to be included when formatting the approximate linear transfer function.[^5] The damping ratio of a fighter aircraft should be as great as possible between 0.35 and 1.3.[^6] The natural frequency of a fighter aircraft should be between 0.28 and 3.6.[^6]
[[Lateral Control Divergence Parameter]]
F-22 Initial Short-Period Mode Specifications – CAP of 0.35
[[BP3.2]] – do not violate the MIL-F-8785C Level 1 Boundaries
Sources
- [1] “Wing Rock Prediction Method for a High Performance Fighter Aircraft”.
- [2] Renfrow, Liebler, and Denham, “F-14 flight control law design, verification, and validation using computer aided engineering tools,” in Proceedings of IEEE International Conference on Control and Applications CCA-94, Glasgow, UK: IEEE, 1994, pp. 359–364 vol.1. doi: 10.1109/CCA.1994.381441.
- [3] T. T. IVlyers, D. E. Johnston, and D. T. McRuer, “Space Shuttle Flying Qualities and :Flight ~Control System Assessment Stu«:ly — Phase II”.
- [4] R. Loschke, “Development of the F-117 Flight Control System,” in AIAA Guidance, Navigation, and Control Conference and Exhibit, Austin, Texas: American Institute of Aeronautics and Astronautics, Aug. 2003. doi: 10.2514/6.2003-5762.
- [5] RTO-TR-029
- [6] “Frequency Domain Analysis of F-16 Aircraft in a Variety of Flight Conditions,” IJAST. Accessed: Sep. 27, 2024. [Online]. Available: https://ijast.org/volume-3-issue-1-article-3/
Backlinks:
[[Compliance Bucket]]
[[Dutch Roll]]
[[F-15 Active Flight Control Requirements]]
Reduced Order Models