These plots were obtained working with Designfoil-Snack (demo version).
First of all I was interested to know what happens when you take a profile, cut off their lower side, and attach a LE inflatable bladder. So, I compared the original and the modified versions of the first four profiles (Clark-Y, Clark-YH, MH92, and Eliminator).
In the following plots the original profile is in blue, the modified is in light blue, and the Reynolds number (1e6) corresponds to a 1.8 meter chord and a wind speed of 30 km/hr. (near 16.7 knots), at sea level, temperature of 25 degrees centigrades, 45 degrees south latitude, dressing a yellow short pant. ;-)
What did I learnt?
Modifying profiles for inflatable sleds sometimes rises their
drag, makes their pitching moment much more negative (nose down,
see the MH92!), can lower their max. lift, but the lift is much
bigger for low and even negative AoA (see the modified Eliminator.
Lift is positive even for a -10 degrees AoA!!). Also the Cl Vs.
AoA curve peak is less severe. I guess it means better stall
behavior (?).
I also took a look at the Cp plots. Some of the airfoils can show
bubble separation, although I guess fabric wrinkles and other
surface irregularities will prevent that problem.
Interesting...
Here are all the originals together:
And all the modified together:
Now let's see some comparisons between different profiles: Page three
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