<< A cambered foil does not need an angle of attack to generate lift.  >>

I pointed just this out in my original email, but got a bit lax in my reply to you:

"The final plot shows Cl/Cd plotted against angle of attack.  This graph is problematic in that angle of attack differs from lift angle.  Observe that all the foils generate lift at negative attack angles.  It would make more sense to draw this graph with all foils showing zero lift at zero degrees - what I term, lifting angle.  These results are a function of the coordinates supplied to the program, so only really make sense if we mentally shift all curves to share a common Cl/Cd point."

The foils are generating lift from less than -3 degrees. The drag bucket kicks in at 1.6 degrees AoA, so 5 degrees lift angle.

You're not too far off the money with Cp, but the results are better.  These are AoA: 5 degrees -2.8 Cp; 4 -2; 3 -1.3, 2 -0.8; and 1.7 -0.66.  At which point the pressure distribution is flat, the Cl is above 0.6 and Cl/Cd over 70.  In fact the foils perform better than the Eppler and the H105 on the Xtr plot.  These figures are for the thinner of the two boards - the AoA pressures are better on the thicker of the two.

<< More likely lower than that due to surface irregularities.>>  Not to mention surface piercing ventilation.

When it comes to Froude effects, I am not overly concerned - but I confess I haven't quantified the effect.  The foils are 8.64% and 9.34% thickness respectively, with 3.38 and 3.73% camber.  I'm working on the theory that thin foils will exhibit low wave making resistance.

Note these pressure figures only apply to this Reynold's number (2 million), so I'll have to run more analyses at higher Reynold's in order to assess pressure distributions at higher speeds.

Thanks Rick, you're keeping me on the ball.

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