G3-suit. VKB

[Buried 0]

what is the red cord(?) that goes around the top (back) part of the suit for? cutaway? design?

Where is my fizzy-lifting drink?

[Gibolin 0]

Hi colm!
Your questions bring me some more questions: what is the Reynolds number and in what is it interesting for wingsuit building? How can you determine the coefficient of lift. I tried to measure the angle of attack of my 1st prototype by filming a good friend of mine flying in front of me while both freefalling. Then I've measured the angle on my TV screen!...I also tried to measure it with a dummy attached to the center of gravity, so the forces would compensate themselves after a while and kinda reach "terminal velocity" and be stable. BUT the angle changed with the speed (and my old car will never reach terminal velocity!), so my test was not accurate. furthermore, gravity pulling was a force disturbing the test at 90° (hope you understand my poor English. I speak normally Swiss-French...). I wish I could use a GPS with altitude recorded during the freefall to have the trajectory. Combined with my angle from the video, I should have the correct angle of attack. Does it seem correct to you?
In my opinion, windtunnel tests should be performed with dummies having the correct angle of attack, otherwise you only have a part of the answer after the tests...

Keep being creative! Boris "the Gibolin"

Gibolin from Switzerland

[KrisFlyZ 0]

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PS: It is 3k to the other side of that valley where he jump. When he reached the other side he had to turn down valley to keep on flying that futuristic thing!

Is this as observed from the exit point, the landing area or a GPS log after the jump? Can someone post some glide numbers please?

Kris.

[Colm 1]

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Your questions bring me some more questions: what is the Reynolds number and in what is it interesting for wingsuit building? How can you determine the coefficient of lift. I tried to measure the angle of attack -snip-

disclaimer: I'm a pilot not an engineer

Reynold's number, in a sense, has to do with the drag of the fluid (air) over the surface of the object (the jumper). It is useful in scaled experiments such as small wind-tunnel models. Finding the critical reynolds number (somebody correct me if I'm wrong) on the model will help predict important airflow characteristics over a full-size version. So you can subject a small model to wind tunnel tests that you couldn't do on a real person, and get useful information.

Angle of attack is the angle between the chord of an airfoil (i.e. a straight line from a tracker's head to his toes) and the wind vector. If you wanted to estimate your AOA while you jumped 1) install an AOA vane on your body somewhere, or 2):
- use video to determine X while you track, where X is the angle between the horizontal plane and the chord of your body
- Determine your glideslope, Y, equal to the angle of your descent path as you track--get this from GPS data (90°=straight down, 0 = going perfectly horizontal)
- Subtract X from Y to estimate AOA (did I get that right?)

Note in the model picture, the AOA is approximately zero or slightly above. As others have noted, this is only possible in a very limited set of circumstances. It's not very useful, because unlike simple vector math, you can't just get a stream snapshot at 90° and also at 0° and expect any useful interpolated data.... the important stuff has to be determined experimentally. It would be interesting to see it at about 5-10 degrees higher AOA, and slightly less camber, I think.

Another thing you'll notice in the model picture is the distinct difference between the laminar flow over the top of the model and the highly turbulent separation underneath. This is basically what an inverted stall looks like... with excessive drag and poor controllability. If you adjusted the camber (i.e. the tracker lifted his forehead a little) I'd expect that to change. But of course, the AOA is probably unrealistic anyway so it is fairly moot.

Coefficient of lift... using C sub L at a given angle of attack, you can predict lift force based on certain factors. If you know the critical angle of attack and calculate C sub L for that configuration, you can find the max theoretical lift. Combine it with coefficient of drag, do some college math, and you can figure out a host of things such as L/D(max), best glide speed, best rate of descent, etc. Many things that might be useful to a nerdy tracker!

I'm sure I've botched the theory terribly... maybe someone like 460 has some insightful comments.

I just want to echo how fascinating this is... I have never heard of anyone looking at tracking in a windtunnel before. That body-wing that flew whats-his-face over the english channel probably went through the wringer too. It's a start.

[Rainer 0]

What is the required hight for this suit?

[crwper 7]

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What is the required hight for this suit?

Looks like 6 feet or so. Sorry, couldn't resist.

Michael

[MB38 0]

There are new updates online

Øyvind sent me a document discussing the suit's design, wind tunnel tests and jumping. He also sent an Excel document with GPS plots and wind tunnel data.

If you don't see the links right away, reload.

Enjoy.

[P.S. - at Øyvind's request, I cleaned up spelling and some (not all)grammar in the document]

I really don't know what I'm talking about.

[mccordia 74]

Stats are cool...video would be better

JC
FlyLikeBrick
I'm an Athlete?

[KrisFlyZ 0]

Yeah, it would be nice to watch the video.

Kudos to the VKB guys for posting GPS data. Even though it shows what someone posted here as 3km to be false.

It also looks like if flown a bit slower(less steep?) there is more glide to come from the suit. Travelling 150 mph plus must be pretty nice too.

Kris.

[mccordia 74]

Other question for the you VKB folks...

A lot of people have been talking about landing a wingsuit and how groundeffect might come into play..

Completely ignoring the landing of a wingsuit (dont want to start another discussion on that...do a search if anyone cares)

But flying as close to the ground/cliffs as you guys do..

When you are flying over edges etc. Do you get any extra noticable lift or turbulence coming from the rocks? Or is a track/wingsuit simply to small to really produce any noticable effect?

Just wondering....?

JC
FlyLikeBrick
I'm an Athlete?

[pattersd 0]

Try doing a search on ground effect lift. You might figure out that you would have to be darn close to the ground to realize any benefit from ground effect. ground effect is a function of airfoil span.

[LukeH 0]

i recall hearing somewhere that groundeffect only happens when you are < half the wignspan above the ground.

[nicrussell 0]

half of the wingspan is correct. So to notice this effect you would need to be within 3 feet or less.

[pattersd 0]

half the wingspan is where some noticeable effects (approximately 10 percent reduction in induced drag) start occurring at 10 percent of the wingspan (what is that? 7 inches) you would get a 50 percent reduction in induced drag. and remeber that induced drag is a small percentage of the lift. Basically, ground effect is not going to provide much help in landing a wingsuit.

[mccordia 74]

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Basically, ground effect is not going to provide much help in landing a wingsuit.

I wasnt really interested in the landing idea...but just curious about any effects the close proximity to the walls might have on ones flying..

JC
FlyLikeBrick
I'm an Athlete?

[FatSnake 0]

About the effects of close proximity:

Have't felt any difference while flying close. Regarding turbulence: From time to time windy conditions occur. I tend to fly a little less close in those situations.

And while I am writing, not that it is an answer to any the earlier posts. There are in my opinion two easy and basic rules for for close flying:


1. Fly down to objects, not above objects
2. Fly towards objects, not away from objects

If rules are followed a human mistake will take you further away from danger. On video it is hard to see, but in reality it normally means you dive while flying.

Fly low, pull high....VKB#7

http://www.fatsnake.com

[MB38 0]

A new polar graph, an updated tunnel/jump document and two new pictures are up

I really don't know what I'm talking about.

[TomAiello 26]

I'd love to see Robi go up there (or Yuri, or Loic) and somebody shoot some relative footage with a top end wingsuit pilot to compare forward speed and fall rate (and heck, hook the wingsuit up to the VKB instrumentation too).

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[Basjkall 0]

First of all, why?

Second, they`re not able to follow him anyway..

[LukeH 0]

This setup is not a wingsuit nor is it trying to be one.

Forward speed will obviously be higher because of the lower drag. (Core to the design) However fall rate will be higher, because of the lower surface area (even with good lift creating ability).

Glide ratio I would expect to be lower than that of a good WS Pilot in one of the high end suits.

Different sites and different styles of flying require different tools. Sugar glider (I mean pre GS1) V2 and the G3 are three very different animals designed for different things. But I'm sure all are lots of fun.

[Gibolin 0]

Great explanations Colm, thanks a lot. I think I'd better try to make some money to buy myself a day with engineers in a pro windtunnel to discuss and measure all this. Your answer gave me the will to do it ! For now, I'll test my prototype in the air for more than the two jumps I've already done and try to collect some datas with the help of a good friend whose project is also a bit crazy. Have a look at his website. His name is Yves Rossy. We just live next door! www.jet-man.com Enjoy!

Gibolin from Switzerland

[MartinRosen 0]

I can totally agree to Espen/Fatsnakes thoughts about the 2 rules of close flying.

Also I have never felt any groundeffect, and its true you need to be very close/ far beond safe close to the object to get the effect and the surfice have to be smooth.

Though in very hot and thermic weathers I have felt lift/turbulence. This kind of lift isnt very comfortable so I tend to keep distance.

I have still my V1 and have still a problem to fly down to things. Im headding fr a smaller and faster suit that can fly very steep and exact.

Another thing to think about. If youre trying to fly close to an object. make sure you are flying so steep that you can easely lift far above the place if you feel that you are in a bad spot. As soon as you breake, stall or flattern out your suit you are lost.

Keep it steap, keep it exact and follow the 2 rules from Fat snake.

/martin - getting a smaller suit for next year.

/Martin - Team Bautasten of Sweden

[MB38 0]

News video.

I'll be pulling my website soon, VKB is putting up their own.

I really don't know what I'm talking about.

[saf40 0]

The NRK video is also on SDM.com http://www.skydivingmovies.com/ver2/pafiledb.php?action=file&id=5122

[MartinRosen 0]

Great work Guys.
The show it self is really good. Its a positive show, its about sience and developing (for real this time, no fucking 6-gainer developing such as in Twin falls) This is the real thing.

The NRK Crew seems interested and you got to show it all.

Lets do some more stuff next weekend guys, Im coming to you to play again. hehe.

Anyway , Im glad to hear what they are saying. Its developing just to get a sience show in TV about BASE.

/martin - who understand what they are saying ;)

/Martin - Team Bautasten of Sweden