[Closed] What altitude for wingsuit ground effect?

No way! that must be a hover suit
or he's on a wire..

He's descending at the normal rate, just found some ground that matches his angle of descent.

Balls of steel but negligible ground effect, he is closer in size to a large bird than that mad Russian Ekranoplan, birds fly inches above the sea, big GEV's a few feet, so he would need to be closer to the ground than on that film at a guess.

Couple of clicks in from that, not up to Danny Mc's production standards, but still some pretty impressive stuff.

Not convinced there would be any ground effect to speak of on a wing suit (it's not the traditional "cushion of air" that we believe it to be), but if any then it will be within about half the wingspan above the ground. So below 3 feet.

I would have thought he is a bit far from the ground for ground effect and he doesnt really have wings such that create proper lift and vortices.

But it could be that he does benefit some ground effect if he gets too close that is enough to push him away again and stops him hitting the slope.

Plenty of birds use ground effect and there is probably some formula/relationship like the height must be around the same as the wingspan or half wingspan but it's been a fair few years since I did aerodynamics.

Ground effect requires you to be within one chord length (leading to trailing edge of wing, mean if the wing isn't square) of the ground to see it occur. Strong (chord dominated, like the Russian ekranoplans used) ground effect doesn't really kick in until maybe 1/3rd of chord.

So assuming a mean chord of say 3ft, to be getting any appreciable ground effect he'd need to be within around a foot of the ground. That's the wing, so he'd likely be scraping his toes! And that's before we get into if his suit will use ground effect efficiently.

Ground effect requires you to be within one chord length (leading to trailing edge of wing, mean if the wing isn't square) of the ground to see it occur. Strong (chord dominated, like the Russian ekranoplans used) ground effect doesn't really kick in until maybe 1/3rd of chord.

Are you sure it's related to chord length? I know the Ekranoplanes had quite low aspect ratio wings but that doesnt sound right.

Just to address a couple of previous comments, there's two components at work in ground effect, span dominated and chord dominated (I think I've got them the right way round). Chord dominated is based on the 'cushion' or ram air principle, while span dominated affects the formation of wingtip vortices, giving you much higher lift to drag.

The cushion effect typically give you more lift but you have to be closer to the surface.

That is about all I can remember other than the fact trying to do stability calculations in ground effect is a nightmare. Some time back now, but a lot of my life at uni I won't get back!

Yeah, low aspect ratio is pretty common. That's not the aim though, it's the low chord. Any more span would just be extra weight. Inverse deltas are generally accepted to give favourable stability characteristics in higher ground effect and give you that nice long chord, hence designs like this- [img] [/img]

just been re familiarising myself with it all too. Chord or span length (different effects).

Have my notes on my shelf in my office, really should read back through them all.

The ram air effect you mention sounds familiar and is something which could possibly apply in the wingsuit case if he does get close to hitting the side of the hill. It's all too easy to forget anyone in a wing suit is not really flying but falling in a slightly more controlled manner so the actual lift is not as much as it looks in these cleverly shot videos.

Who gives a rat about the science , kudos to the guy with the big balls.

indeed, but maybe think twice before lending him any money...

Thing is, when you get POV footage it always looks like they're skimming along in flight. When you see them filmed from the side it's much more like Buzz Lightyear - falling with style. There's a reason why they always go down mountainsides which are more than 45 degrees steep. I don't think they would have any ground effect worth speaking of.

Great vid though.