Tom Speer has put together lots of detail on this with useful charts.
I have mostly played around with span efficiency (or pressure profiles) on prop blades. I realised there how important it is. I also know that it is not commonly appreciated although we walk past it all the time. Have a look at the electric fan in your car!!
One recent learning of mine is that the span efficiency of a fast moving surface piecing foil is the same as one under the hull providing it is not ventilating. So the span efficiency is 2 when not ventilating but drops to 0.5 when ventilating. A NACA0012 foil will ventilate above about 10 degrees AoA depending on the Reynolds number. Blades with sharper nose will ventilate with smaller angles. It is the 4:1 variation in lift that causes the control problem with ventilation.
If NACA0012 rudders are used without a board they will already have leeway of a few degrees so the available range in one direction reduces below 10 degrees - maybe no more than 6 degrees.
Rick
On 07/06/2011, at 11:22 PM, jhargrovewright2@juno.com wrote:
Rick,I am reading and re reading everything that you write.....keep it up.JIB
Rick Willoughby
03 9796 2415
0419 104 821
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