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Helicopter encounters with aircraft vortex wakes

Published online by Cambridge University Press:  04 July 2016

G. D. Padfield and
G. P. Turner
G. D. Padfield
Affiliation:
Aerospace EngineeringThe University of LiverpoolLiverpool, UK
G. P. Turner
Affiliation:
Defence Evaluation and Research Agency Bedford, UK
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Abstract

This paper presents the results of a study into wake vortex-related safety issues associated with simultaneous rotary and fixed-wing aircraft operations at busy airports. An analysis conducted using both simple analytic models and high fidelity FLIGHTLAB simulations has considered a helicopter located in the hover above the landing point and during approach and landing. Tip vortices from a Boeing 747 are shed and are assumed to be travelling in a horizontal plane by the time they reach the helicopter. A worst case scenario is simulated, with no vortex ageing or attenuation due to ground effect. Both simple and high fidelity simulations indicate that the rates of climb and descent induced by the vortex tails can be significant. When the helicopter flies through the vortex core, moderately large transient excursions in attitude occur within a few seconds. When the helicopter does not pass through or close to the core, while the flight path perturbations are still significant, the attitude response is shown to be significantly reduced. The predicted cyclic control power required to counteract the vortex-induced hub moments is about 40% of full control, compared with more than 100% for an ‘equivalent’ fixed-wing aircraft. The control power required in the vertical, collective, axis to overcome the downdraught and updraught in the vortex tails can be as high as 15–20%. While the authors have not tried to make judgements as to whether pilots would find the transients manageable, an approach to quantifying the extent of the hazard has been suggested using the failure transients criteria from the handling qualities performance standard ADS–33. Combined with analysis of the likelihood of such occurrences at particular airports, such response criteria offer a rational approach to developing safety cases for simultaneous operations.

Information

Type
Research Article
Information
The Aeronautical Journal , Volume 105 , Issue 1043 , January 2001, pp. 1 - 8
Copyright
Copyright © Royal Aeronautical Society 2001 

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References

1. Anon. ICAO Annex 14, Vol 2 (Heliports), International Civil Aviation Organisation (ICAO), Montreal.Google Scholar
2. Padfield, G.D. Helicopter Flight Dynamics, 1996, Blackwell Science, Oxford.Google Scholar
3. Burnham, D.C. B–747 Vortex alleviation flight tests: ground-based sensor measurements, US DOT/FAA Report DOT-FAA-RD–81–99, January 1982.Google Scholar
4. Curtiss, H.C. and Zhou, Z. The dynamic response of helicopters to fixed-wing aircraft wake encounters, International Wake Vortex Symposium, Washington DC, 29–31 October 1991.Google Scholar
5. Kim, K.C., Bur, G. and Chopra, I. Helicopter response to an airplane’s vortex wake, Paper No 43, presented at the 12th European Rotorcraft Forum, Garmisch-Partenkirchen, Federal Republic of Germany, 22–25 September 1986.Google Scholar
6. Kodis, R.D. The detection of aircraft wake vortices, Paper No 11, in Flight in turbulence, Advisory Group for Aerospace Research & Development, AGARD Conference Proceedings, 140, May 1973.Google Scholar
7. Kerr, T.H. and Dee, F.W., A flight investigation into the persistence of trailing vortices behind a large aircraft, British ARC CP 489, 1959.Google Scholar
8. Saito, S. et al Numerical simulations of dynamic response of fixed and rotary wing aircraft to a large airplane wake, Paper No 7–1, presented at the 13th European Rotorcraft Forum, 8–11 September 1987, Arles, France.Google Scholar
9. Saito, S. et al Study of the dynamic response of helicopters to a large airplane wake, Paper No 42, presented at the 12th European Rotorcraft Forum, 22–25 September 1986, Garmisch-Partenkirchen, Federal Republic of Germany.Google Scholar
10. Mantay, W.R. et al Helicopter response to an airplane’s trailing vortex, JAircr, April 1977, 14, (4).Google Scholar
11. Anon Aeronautical design standard–33, Handling qualities for military helicopters, US Army ATCOM, 1994.Google Scholar
12. Padfield, G.D. The making of helicopter flying qualities; a requirements perspective, Aeronaut J, October-December 1998, 102, (1018), pp 409–437.Google Scholar
13. UK Defence Standard 00970; Design and airworthiness requirements for service aircraft, Vol 2 Rotorcraft - Book 1, 1988.Google Scholar