Trailing Edge Technical Question

[nicknitro71 0]

Would a semi-rigid trailing edge (both arm and leg wings) give better performance to the suit?

Memento Audere Semper

903

[unclecharlie109 0]

Would depend on suit design and other factors like body position.

Please refine question i.e. if I add semi rigid trailing edges to my S3 will it improve performance?

IMO - No

[nicknitro71 0]

Well yes on the S3.

I was thinking about reinforcing the edges on all the wings to make them more rigid but not so to interfere with pull time.

Ideas?

Memento Audere Semper

903

[ph8068 0]

If anything, strengthening the trailing edge will actually decrease aerodynamic efficiency, as the trailing edge will now be less sharp.

Strengthening would probably only be an advantage if you were experiencing flapping of the wings. And this could probably be fixed by body position.

[quade 4]

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If anything, strengthening the trailing edge will actually decrease aerodynamic efficiency, as the trailing edge will now be less sharp.

Generally speaking, anything that vibrates (flaps, flutters) is a waste of energy (creates drag), so a slight increase in thickness might be better if it actually is more rigid. Besides which, we're talking about a trailing edge.

quade -
The World's Most Boring Skydiver

[ph8068 0]

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we're talking about a trailing edge.

Yup, for an efficient wing, the air over the top and bottom surfaces of the wing needs to meet smoothly at the trailing edge. This requires the trailing edge to be sharp, just like an aircraft wing.

[quade 4]

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Yup, for an efficient wing, the air over the top and bottom surfaces of the wing needs to meet smoothly at the trailing edge.

As long as the stiffened edge is thinner than the deflection of the flapping of the non-stiffened edge . . . I would think you'd see quite a bit of advantage by stiffening it. A flapping edge 1 mill thick is pretty much useless aerodynamically if it's deflecting +-3 inches every time it flaps.

See what I'm sayin'?

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This requires the trailing edge to be sharp, just like an aircraft wing.

Trailing edges of aircraft aren't always that sharp. Ever look at the trailing edge of a Cessna? --<>----<>----<>-- It's -way- more efficient than any sport parachute and far more efficient than any wingsuit could ever hope to be. All those little diamond ridges aren't there for looks, they make the trailing edge more stiff. It just doesn't make any sense at all to make trailing edges infinitely thin (like a razor blade). Under a certain thickness, there simply is no advantage and may have significant disadvantages.

quade -
The World's Most Boring Skydiver

[ikenever 1]

I am designing and near ready to cut and assemble a wing suit. I am attempting to produce the leading and trailing edges to resemble a birds wing and tail and not that of an aircraft.

[quade 4]

Uh . . . ok.

When you get the same wingloading a bird gets . . . lemme know.

Bird wings are -highly- sophisticated and the product of millions of years of evolution. Every feather, every quill, every subtlety evolved for a specific aspect of flight. Owls have stealth wings that make no noise. Condors have long thin highly efficient wings for gliding long distances with minimal effort. The two are -wildly- different.

Just as I would imagine are the wings of the ideal wingsuit for human flight.

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The World's Most Boring Skydiver

[ikenever 1]

quote: Just as I would imagine are the wings of the ideal wingsuit for human flight.

Thats what we're work'in on

I have the wing loading of a penguin, 6' 205 lbs.

If I was a skinny shit like I used to be I would still work on improving the glide ratio.

[quade 4]

My point was, still is really, that designing a wingsuit for humans doesn't really lend itself toward designs imitating nature in any literal sense. Even birds with the stubbiest wings (that can still actually fly and not just hop around on the ground) have a span far beyond what would be usable at human scales. The bio-mechanics just don't allow for it. We are also disadvantaged due to other scaling and C.G. issues as well as our incredibly NOT streamlined shape.

When I hear people say that humans were built to fly it makes me laugh. Our brains may be capable of understanding and overcoming the limitations using machinery, but the one thing humans were -never- meant to do was be more than a couple of feet off the ground at any given time.

The ideal wingsuit is going to look at a wide range of factors and be designed to fly using human scale, proportions and bio-mechanics. Unfortunately, the bio-mechanics are the limiting factor. Our strongest limbs are well behind our C.G. (if we still want to fly head first) and our other limbs are too far forward and too weak anyway.

Again, just compare what you see in the human body with that of a bird. That great big keeled sternum on a bird is there for a reason and notice how the bulk of the bird is located near and balanced at the wing.

So, what I'm saying is . . . we need a different design than that of a bird.

quade -
The World's Most Boring Skydiver

[ikenever 1]

Thank you for educating me. I didn't know any of this wisdom. I guess I'll forget about flap'ing my wings and trying to take flight.

God I am quite the moron.

Thanks for the heads up!

[gus 1]

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I am designing and near ready to cut and assemble a wing suit.

Pictures!

Gus

OutpatientsOnline.com

[TomAiello 26]

At one point Robibird created some prototype S3+ suits that had a stiffener sewn into the trailing edge. I believe this was partially an attempt to reduce flapping. I'm uncertain if he got good results, or if he's incorporated such a stiffener into the V-1 (perhaps UncleCharlie can tell us).

You might try asking Robert, or, as this prototype was made when he was part of Birdman, just asking someone over there.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[kallend 2,030]

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My point was, still is really, that designing a wingsuit for humans doesn't really lend itself toward designs imitating nature in any literal sense. Even birds with the stubbiest wings (that can still actually fly and not just hop around on the ground) have a span far beyond what would be usable at human scales. The bio-mechanics just don't allow for it. We are also disadvantaged due to other scaling and C.G. issues as well as our incredibly NOT streamlined shape.

When I hear people say that humans were built to fly it makes me laugh. Our brains may be capable of understanding and overcoming the limitations using machinery, but the one thing humans were -never- meant to do was be more than a couple of feet off the ground at any given time.

The ideal wingsuit is going to look at a wide range of factors and be designed to fly using human scale, proportions and bio-mechanics. Unfortunately, the bio-mechanics are the limiting factor. Our strongest limbs are well behind our C.G. (if we still want to fly head first) and our other limbs are too far forward and too weak anyway.

Again, just compare what you see in the human body with that of a bird. That great big keeled sternum on a bird is there for a reason and notice how the bulk of the bird is located near and balanced at the wing.

So, what I'm saying is . . . we need a different design than that of a bird.

And compare the relative sizes of the pectoral muscles between birds and humans. Then there are the hollow bones in flying birds, very light for their length and stiffness.

I believe the bustard is the heaviest flying bird, at around 45 pounds for a big male. Mute swans rach around 30 pounds. Due to scaling issues it is very difficult to get a low wing loading as the size increases.

...

The only sure way to survive a canopy collision is not to have one.

[quade 4]

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And compare the relative sizes of the pectoral muscles between birds and humans.

That's exactly what I was referring to when I was talking about the keeled sternum. That's where it attaches. It's all about the leverage.

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The World's Most Boring Skydiver

[quade 4]

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Thank you for educating me. I didn't know any of this wisdom. I guess I'll forget about flap'ing my wings and trying to take flight.

God I am quite the moron.

Thanks for the heads up!

Not really sure if you took that as an insult or condescending or what. It wasn't meant to be. I certainly never assumed you meant to flap them -- just glide as people do in what we recognise right now as a wingsuit.

People have been proposing bird like wings for a long time and until now at least, nobody has come up with anything that's even close when it comes to a working model.

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The World's Most Boring Skydiver