Hi
Well, stabless gliders we have flown for years, dont need to be low aspect delta or swept wings (both helps hugely on stability), but can be done on a super high AR straight wing, being just as stable.
But it will require an "S" profile to be stable for flying, and will have downsides in handling and turning also simply because you have no stab leverage.
Fly quite well though, no issues, have flown many of these.
The cost is huge, such a profile can fly ok fast and have reasonably low drag, but if you want to have good lift, AND low drag, which is what gliding is all about, to get low sink rate and even more important, max glide, they are pretty useless.
Compared to a fuselage and a small stab - here you gain so much in terms of stability and agility/turning, at almost very low expense (fuselage tail and stab drag), compared to a stabless that in total are a lot worse in terms of lift and lift/drag.
BUT, the interesting thing for hydrofoilin is, if you are sufficiently "fast" reacting, which can be practized into muscle memory, maybe even with low talent, then a hydrofoil is controlled in another way, because of weight balance.
Another surprisingly good effect is the long mast, which is actually dampening the wrong torque of a stabless wing - which we know from having a longer mast makes it actually more stable, compared to a short one.
Reason why we think opposite, is because most or all beginner foils with supershort masts have a bigger stab and or more negative stab lift - so a lot more stable, besides you will never notice if stable or not, as you touch down every now and then with these.
If too long the ability to correct fast is lost though, like a unicycle very high.
Above means you can not compare to a glider/aircraft, where it has to be either self stable, or at least controlled by rudders and not weight.
A hangglider is controlled by weight balancing, but it also needs a combo of semi S shaped profile, combined with wing sweep, or wing sweep with washout, to be sufficiently stable and not a death trap - this is why they have more limited performance, apart from the structural downsides and drag of the pilot.
I also pity those few having a "stab catching weed" things where they ride - I have never had that, actually almost never on my wing either, always on my mast it is a problem with the weeds we got.
On occasion you can hit a big lump of weed yes, but here you go faceplant immediately - no matter what and stab or not
So much weed that it catches the wing also, then it has been over much earlier for any foiling, as the ones catching the mast will stop you foiling these days, a lot earlier than "wing weed".
But back to the topic - we control with our weight distribution on a foil, and we have our COG high above the COE of the lifting wing which dampens the torque, thus possible to ride a non stable wing - really amazing actually.
Also the reason there is a limit probably, to how performant high AR lifting wings you can ride stabless, but depends on skill most likely.
So the fact that you CAN a foil stabless even with a negative pitching effect profile/wing, is true, and quite different from gliders and aircraft IMO
Peter
