Kamikuza wrote: ↑
Tue Jul 30, 2019 12:43 am
Amazing that a 1% difference could make so much of a ... difference
So this is exactly what I said about big wings -- drag increases sure but the LD coefficient isn't hugely different because more lift.
At 20 knots, the difference in drag between those two stabs is ... 30%.
Perhaps the drag we feel and complain about is just the 1% difference...
I dont think so really
When you decrease the stab 30 %, the foil becomes these 30 % more lively, which is a HUGE difference in feel
It gets so light and agile when you turn the foil now, and still easy to ride
The overall 1 % less drag, noone can feel I am pretty sure
Yes, the big wings got the same lift/drag coefficient, so they can go upwind in the same angle, great
In fact, just made some comparisons now, the bigger wings if same AR, can go more than 6 % higher to the wind than one half the size, because of the "fixed" drag, and because in lighter winds slower foils can go at a higher angle although usually still slower VMG.
But the half sized small wing will only have 47 % of the big wing foils drag, thus being able to ride 30-35 % faster upwind in VMG. Depends on windstrength both are used in, thus not that easy to compare.
At max speed, the small one no matter if high or low AR, will have 41 % less drag, meaning able to ride 30 % faster (drag and lift increases squared with the speed, thus not 41 % faster speed).
But they are not same AR, so if we have a 1200 cm2 wing 3.6 in AR, and we change to a 600 cm2 wing same span, meaning 7.2 in AR, then it changes a lot upwind.
Now the 600 cm2 foil only got one third the drag compared to the 1200, thus able to ride 55-65 % faster upwind in VMG.
And, the angle to the wind can be 36 % higher.
That is a huge difference, and the reason racers use smaller and higher AR wings of course, except for superlight winds where bigger sizes, still high AR, are chosen.
Luckily it does not matter much (apart from in marginal winds) for us freestyle/freeride/waveride hydrofoilers, where medium or big wings are awesome.
Would just put some numbers on this, now some of you asked, and I had fun joggling with this