WinDesign vpp - heel angles, 14k lower than 12k

[idkfa]

Hello all,

Got some results here of a WinDesign-vpp test I'd appreciate some help with. At wind angle 32degrees, the heel angles for wind 14+ are lower than for wind 12-! and subsequently the speed as well.

Heel angles:

8 9 10 12 14 16 20
32 15.43 18.7 20.35 22.47 6.01 7.77 11.83
36 16.94 20.02 21.35 23.18 24.22 24.88 25.78
40 18.13 20.93 22.11 23.55 24.32 24.87 25.74
45 19.15 21.74 22.63 23.67 24.36 24.9 25.77

Is it, at the higher windspeeds the sails were "further" flatten to keep the airflow laminar, and now they're so flat, that the lift/heeling moment created was very small? But if so, why is the change apparent at 12-14knots?

Any ideas?


Thanks idkfa,

[idkfa]

Heel angles:

8 9 10 12 14 16 20
32 15.43 18.70 20.35 22.47 6.01 7.77 11.83
36 16.94 20.02 21.35 23.18 24.22 24.88 25.78
40 18.13 20.93 22.11 23.55 24.32 24.87 25.74
45 19.15 21.74 22.63 23.67 24.36 24.90 25.77

that's better,

[idkfa]

Heel angles:

.....8......9......10......12.....14.....16......20
32 15.43 18.70 20.35 22.47 06.01 07.77 11.83
36 16.94 20.02 21.35 23.18 24.22 24.88 25.78
40 18.13 20.93 22.11 23.55 24.32 24.87 25.74
45 19.15 21.74 22.63 23.67 24.36 24.90 25.77

(pressing the submit button, hold your thumbs!)

[Tim B]

hummmm, very interesting.

Since it doesn't happen at any other angle, I shall suggest that you are the proud discoverer of a glitch. It almost certainly shouldn't happen in real life, assuming the same set of sails. If I were you I'd get it to do it again with less percious input data and send the whole lot to tech support.

Alternatively, you can add 18 degrees to those that are too small to make them look right <grins> but personally I'd take it up with tech support.

Cheers,

Tim B.

[nico]

Have a look at the FLAT and REEF values, (a few pages after heel values), and find out if the values are much lower.
Another thing you can look at, is to fix REEF at 1 (Opsets-> No reef)