Planing pressure

[messabout]

How does the basic aerfoil lift equations apply to a waterbound planing surface? I am told that beam (width of leading edge) is a determinant that causes lift to increase as the square of the impact width. Also lift increases as a function of the square of velocity. Those are suspiciously intuitive determinants.

There are, no doubt some, equations that I can wrestle with. Where are they to be found? It is clear that flat surfaces will generate more lift than deadrise surfaces of equivalent width. I reckon that vector sums are involved with curved or vee surfaces.

I am also interested in the pressure distribution, as applied to surface areas, progressively aft of the impact edge. Then there is the tip vortex phenomena. Probably does not apply as nearly to water as with air on account of viscosity. Spay is visible nonetheless.

Your help respectfully requested.

Gene

[dougfrolich]

Look to the 'Planing Vessels' section starting on page342 of "Hydrodynamics of High Speed Marine Vehicles" by Odd Faltinsen, available from Amazon. That is the most concise discussion of planning hulls that I know of.

[messabout]

Doug:
Thanks for the reference. That is not one of the books im my library. I do have some old books. Among them, Naval Architecture of Planing Hulls; Lindsay Lord. Lord discusses planing pressure adequately enough, but it is old copy that has since had the benefit of additional and sometimes contradictory, research and thought. I mean no discredit to L. Lord. I'll get a copy of the Faltinsen book. Comparison should be interesting.

[jehardiman]

Originally Posted by messabout

How does the basic aerfoil lift equations apply to a waterbound planing surface?

They don't....

Hyroplaning surface development is based upon momentum (i.e. impact or kenetic energy) theory, not circulation (i.e. streamline) theory. Same difference as a Parsons/Rateau (impulse) turbine stage and a Curtis (reaction) turbine stage.

[RANCHI OTTO]

I have in the past measured the pressures at speed up to 50 knots at various points at the bottom.

The results were closed to the BV estimations.