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Investigation of rotorcraft-pilot couplings under flight-path constraint below the minimum-power speed

Published online by Cambridge University Press:  03 February 2016

L. Lu ,
G.D. Padfield  and
M. Jump
L. Lu
Affiliation:
Linghai@liv.ac.uk
G.D. Padfield
Affiliation:
Flight Science and Technology Research Group, Department of Engineering, University of Liverpool, the Quadrangle, Liverpool, UK
M. Jump
Affiliation:
Flight Science and Technology Research Group, Department of Engineering, University of Liverpool, the Quadrangle, Liverpool, UK
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Abstract

In some situations, closed loop control by the pilot can result in the combined pilot-aircraft system becoming marginally stable or even unstable. This can happen whether the pilot is controlling attitude or flight path. In this paper, an investigation into helicopter stability under flight-path constraint below the minimum-power speed is reported. The work provides a theoretical basis for flight path handling qualities criteria particularly for flight on the, so-called, back-side of the power curve. The research uses the theory of weakly coupled systems by partitioning the helicopter longitudinal dynamics to investigate three interacting subsystems – classically the surge mode, the phugoid mode and the heave mode. Under certain conditions, strong control of flight path or vertical speed is shown to drive the aircraft-pilot system unstable and a conflict is shown to exist between feedback gain values to guarantee stability of both the surge and the flight path motions. This conflict constitutes a potential source of adverse rotorcraft-pilot couplings. The problems are exacerbated in cases when the use of collective control is restricted. The phenomenon is explored in both ground based simulation and flight test to provide a verification of the theory.

Type
Research Article
Information
The Aeronautical Journal , Volume 114 , Issue 1157 , July 2010 , pp. 405 - 416
Copyright
Copyright © Royal Aeronautical Society 2010 

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References

1. McRuer, D.T., et al, Aviation Safety and Pilot Control Understanding and Preventing Unfavourable Pilot-Vehicle Interactions, ASEB National Research Council, National Academy Press, Washington DC, USA, 1997.Google Scholar
2. Mitchell, D.G. and Klyde, D.H. Identifying a PIO signature – new techniques applied to an old problem, J Guidance, Control and Dynamics, January 2008, 31, (1), pp 215–225.Google Scholar
3. Klyde, D.H. and Mitchell, D.G., Investigating the role of rate limiting in pilot-induced oscillations, J Guidance, Control and Dynamics, September 2004, 27, (5), pp 804–813.Google Scholar
4. Padfield, G.D. and Lawrence, B., The birth of the practical aeroplane; an appraisal of the Wright Brothers’ achievements in 1905, Aeronaut J, October 2005, 109, (110), pp 421–438 Google Scholar
5. Shafer, M.F. and Steinmetz, P., Pilot-induced oscillation research status at the end of the century, NASA Dryden Flight Research Center, Tech Rep, April 2001.Google Scholar
6. Pavel, M.D. and Padfield, G.D., Understanding the peculiarities of rotorcraft-pilot couplings, Proc 64th Annual Forum of the American Helicopter Society, Montreal, Canada, May 2008.Google Scholar
7. Lu, L and Padfield, G.D., The strongly controlled helicopter, 34th European Rotorcraft Forum, Liverpool, UK, 16 – 19 September 2008.Google Scholar
8. Jump, M., et al, Adverse rotorcraft-pilot coupling: test campaign development at the University of Liverpool, 34th European Rotorcraft Forum, Liverpool, UK, 16th – 19th September 2008.Google Scholar
9. Walden, R.B., A retrospective survey of pilot-structural coupling instabilities in naval rotorcraft, 63rd Annual Forum of the American Helicopter Society, Virginia Beach, VA, USA, 1 – 3 May 2007.Google Scholar
10. Padfield, G.D., Helicopter Flight Dynamics, 2nd ed, Blackwell Science, Oxford, UK, 2007.Google Scholar
11. Neumark, S., Problems of longitudinal stability below minimum drag speed, and theory of stability under constraint, Aeronautical Research Council, R&M 2983, HMSO London, July 1953.Google Scholar
12. Pinsker, W.J.G., Glide-path stability of an aircraft under speed constraint, Aeronautical Research Council, R&M 3705, HMSO London, February 1971.Google Scholar
13. Pinsker, W.J.G., Directional stability in flight with bank angle constraint as a condition defining a minimum acceptable value for Nv, RAE TR 67 127, June 1967.Google Scholar
14. Milne, R.D. and Padfield, G.D., The strongly controlled aircraft, Aeronautical Q, May 1971, XXII, (2), pp 146–168.Google Scholar
15. Milne, R.D., The analysis of weakly coupled dynamic systems, Int J Control, August 1965, 2, pp 171–199.Google Scholar
16. Hodgkinson, J., Glessner, P.T., and Mitchell, D.G., Prediction of longitudinal pilot-induced oscillations using a low order equation system approach, NASA/CP-2001-210389/VOL2, April 2004, pp 67–80.Google Scholar
17. Hess, R.A. and Kalteis, R.M., Technique for predicting longitudinal pilot-induced oscillations, J Guidance, Control and Dynamics, 1991, 14, (1), pp 198–204.Google Scholar
18. Anon, 2000. Aeronautical design standard performance specification handling qualities requirements for military rotorcraft ADS-33E-PRF. US Army Aviation and Missile Command, Aviation Engineering Directorate, Redstone Arsenal, Alabama, USA, March 2000.Google Scholar
19. Manimala, B.J., et al, Rotorcraft simulation modelling and validation for control law design, Aeronaut J, February 2007, 111, (1116), pp 77–88.Google Scholar
20. Dieterich, O., et al, Adverse rotorcraft-pilot coupling: recent research activities in Europe, 34th European Rotorcraft Forum, Liverpool, UK, 16 – 19 September 2008.Google Scholar
21. Pavel, M.D., et al, Adverse rotorcraft-pilot couplings – prediction and suppression of rigid body RPC, 34th European Rotorcraft Forum, Liverpool, UK, 16 – 19 September 2008.Google Scholar
22. Padfield, G.D. and White, M.D., Flight simulation in academia; HELIFLIGHT in its first year of operation, Aeronaut J, September 2003, 107, (1075), pp 529–538.Google Scholar
23. Duncan, W.J., The Principles of the Control and Stability of Aircraft, Cambridge University Press, 1952.Google Scholar