KrisFlyZ

Tip Vortex(center parallel to chord) ======== Due to the pressure difference between the upper and lower surface of the wing, a vortex is formed at the tip of all finite wings. The result of the vortex formation is an increase in the drag. This drag is related to the amount of lift produced. The vortices can be visualized in "holy smoke" and "Fly the Line" videos(yellow smoke). Induced drag is proportional to the square of the weight and inversly proportional to square of velocity, square of span and inversely proportional to density. This may explain why BASE flights are better and why people rave about flights in 'clean air'. In the traditional sense L/D = Cl/Cd and this is not effected by density. Weight increases at a faster rate than strength in muscles. Trying to increase strength too much, due to the cost of increased weight is not beneficial to wingsuit performance. Look at how gliders of massive wingspan still have wingtip devices to deal with tip vortices. search for "eta glider" and look at the pictures. If it is significant for then, the relative importance of induced drag for wingsuit flight is more given the short span, the slower speeds and the amount of wing area that is effected by the tip vortex. Can induced drag be reduced for wingsuit flight? We cannot reduce the other forms of drag for a given person and a given wingsuit. a) Drooping tips and Spanwise Camber. There is published research material that shows that wings with spanwise camber and a wingtip at 90 degrees to the flow reduce induced drag. Another effect of drooping wingtips is that they create suction at the leading edge. b) Spanwise twist. This along with a wingtip at a negative(that is correct negative) angle of attack is supposed to create a 'beneficial vortex' (US Patent 5634613...Prof Kallend, your input is much appreciated). Beneficial being in the opposite direction of the tip vortex at the tip in question. We cannot use angle of attack loosely anymore. This is not necessarily constant across the span. Bound Vortex(Center parallel to span) =========== Search inside the book "Nature's Flyers: Birds, Insects and the Biomechanics of Flight " on amazon.com and search for "bound vortex trailing edge" there is a nice explanation on page 23 and 24.

Does the use of a Trango mean reduced PC size? Or is a 36" still the 'standard'? Kris.

Will do when I have a wingsuit Kris.

What if you dont fuck up and still die in a BASE jump? Could you then care if you tried? Seems to be a misunderstanding. My point was that if I was on the list, it would be impossible for me to care. Regardless of whether someone thinks it was a mistake or not. I think that dying without doing any mistake at all is a romantic notion. There is no such thing. Choosing to leave or not leave(the edge) is the biggest thing we have in our favour. Leaving the edge is itself the mistake, if the jump ended in a fatality. FWIW, I voted option 1 as well . Kris.

Nice

Not directed at you Chuck. I think Ed(or I completely lost the plot) just predicted where this thread was going, based on prior experience in this forum Kris.

Dude, if I fuck up and die in a BASE jump, I am pretty sure I couldn't care if I tried . Kris.

Are you entertained ? Kris.

I thought the logs from your first post were wingsuit jumps. Get really comfortable in the suit before worrying about any of the things I said. Kris.

Absolutely agree with that. Just trying to keep my ramblings short. Kris.

What is your height? I got your weight from the wingloading and canopy size. How is your weight distributed? Do you have longish legs and a lot of weight around the torso? Just a few things that might help. The attitude of the body can be controlled relative to the horizon. Let us say you closed your arm wings and fully spread the legwing, it is possible to not get headlow or even go head high if you want to. Try this without wearing your wingsuit(arms along the sides and legs spread) or wearing a small suit and at high altitudes to allow recovery in case of instability. Kris.

Hi Tony, This post was just meant to be a theoritical discussion. Reynolds number or biggest chord does not mean anything. When applied to the regime that we fly our wingsuits in. Bigger wing chord in a wingsuit does not imply better glide. It does have some advantages for arm wings. Be happy to discuss if you are interested. Afterall, the biggest chord anyone can get (whole body as a wing) is when we track. As soon as we start spreading the legs, the chord reduces and the velocity reduces(at best glide). Adding wings reduces the velocity even more at best L/D speeds. Reynolds number for a wingsuit flyer will be lower than the same person's Reynolds number in a track. Does anyone track better without a wingsuit than in one? Kris P.S: I met you at the Richmond Boogie in 2004. Came to see if you could help hook up my GPS on my helmet. You suggested sewing a pouch on the GTI and I chickened out.

That may be a possibility . Kris.

Yup, The wings container has the reserve PC top visible. This is more likely a Paratec Next. Kris.

Suits tailored for performance should be tight. When standing upright, we should feel the the suit on the shoulders. A snug fit means that we don't have to tear our shoulders out of the sockets to stretch the fabric chordwise. If a suit fits like this, very little effort is needed to go to the max flying posture and this allows for a longer maxed out flight. Infact, if a suit is loose, the max flying posture(which involves relaxed(spanwise) and sweptback arms) is not possible at all. Kris.

It is not about good or bad reynolds number. In the range that all humans fly, nothing definate can be said about what body shape/size is better because of its reynolds number. The point of the post is not to try and prove one is better than the other, it is to show that the range of reynolds numbers that we fly at is actually a good thing. Lower reynolds numbers when flow is streamlined but viscous forces dominate(that would be like trying to move a wing thru honey to generate lift) does not allow good L/D. Birds have this information ingrained chemically in thier brains(?), they do know all this stuff. We can learn a lot by observing them or by reading the published works of people that have spent a signifcant amount of time doing that. Here is an example. The article has important information that one can apply to their wingsuit flying, if they were so inclined. Kris.

Then why did only 3 people out of 13 get the correct answer? http://www.desktopaero.com/appliedaero/fundamentals/reno.html Anyway, the chord length or the mean chord length is the characteristic length used to calculate the reynolds number for a wing. Kris.

Choose the correct answer.

Not arguing that the list has no use. The following is just an observation. I don't think that the list really deters anyone from entering the sport. More likely than not, someone wanting to enter BASE that reads the list is going to think "I have read about this person and how (and in some cases why) he died, so it is not going to happen to me( or I know how to avoid it). " Without some kind of rationalization that amounts to "it is not going to happen to me", it is not possible to enter the sport. Regardless of what people want to say now. Kris.

People's proportions vary too, so even a constant angle may not be enough (in the case of weirdly proportioned people). Ofcourse, people's proportions vary. The discussion was about leg wing width. Talking about width of a legwing without specifying inseam measurement is ambiguous. If you read Nick's note, you can see that he compares leg wing width's of different suits for a given inseam length. The really custom part of a wingsuit is the body of the suit*. This has to be made to the individuals proportions. Wing angles will still remain constant. Customization beyond that is non existant and not economically viable. Kris. *Most wingsuit manufacturers have a background in building RW/FF suits.

Looking good

Tony-suits Eagle? I think you'd be splitting hairs to say that arm wing isn't straight Sure...and how many people use that suit as their weapon of choice for performance flying? . Kris.

It looks like the leg wing has a lot more ribs than before and probably extends down a bit more(more area). Kris.

yes, he was going to shorten the width by 3-3.5 inches or so and extend the wing by an inch or so. making it just under a vamp's width. Think angle guys

Nope Seriously though. You know this, obviously. With the limitations placed by the human form, it is not possible to have any other design. Not having some amount of sweepback is simply not an option. Kris.