GlosMikeP

The formula I used for many years to calculate aquaplaning speed on a contaminated runway was one I got from an old flight safety film that showed US aircraft landing under various adverse circumstances.

The research concluded aquaplaning would start above the speed given by:

8.6 x sqrt tyre pressure in psi

So 2 questions:

1. Is there a better, proven modern calculating method?
2. Does it apply to any tyre (for e.g. a car) or is it restricted to ac tyres through some limitation such as tread pattern?

safetypee

Extract from PROCEEDINGS of the 2nd International Meeting on Aircraft Performance on Contaminated Runways. 1999
Caution large file – 11mb.
“Based on the results, Mr. van Es concluded that modern aircraft tires have lower hydroplaning speeds than those predicted by the well-known and commonly accepted equation developed by Mr. Horne of NASA. He stated that this was because of the differences in the footprint dimensions of the newer tires as compared to the older bias-ply tires.”
The diagram in the presentation indicates that the hydroplaning boundary ranges from 9*SQR tire pressure to 6*SQR tire pressure.

GlosMikeP

Thanks for that, I'll have a read. It always puzzled me how there could be just one equation for all cases. I never quite believed it.

safetypee

Interestingly, EASA stay with the old equation, but there are many other considerations involved in landing. Operation on Contaminated Runways.

The Canadians have done a lot of work in this area –
Overview of the Joint Winter Runway Friction Measurement Program, November 2004 (TP 13361)
Most of the references are available via Transport Canada web site.

And one more equation
Vacq(kt) = SQR(tire press / sg of contaminant)
Ref Getting to Grips with Performance see page 82; an Airbus document (8mb)