Wind Tunnels’ Long Term Effect on Competition

[murrays 0]

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Also, remove the danger of the actual skydive and very few people would see the difference between 4-way and square dancing.

Quade, I think square dancing is more physically demanding than the Winter Olympic sport of ....Curling. Well, maybe when you have to sweep like a mother to "drag" a stone it's more demanding than square dancing but that is about it. (You Californians know all about curling don't you? )

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Murray

"No tyranny is so irksome as petty tyranny: the officious demands of policemen, government clerks, and electromechanical gadgets." - Edward Abbey

[drewboo 0]

Than again you have synchronized-swimming...also a thrill.

[kallend 2,026]

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Than again you have synchronized-swimming...also a thrill.

Synchronized swimming would draw a larger audience - the girls' bodies are displayed much better than in a wind tunnel.

Maybe if the tunnel event was done naked...

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

[ThomasHughes 0]

What difference is it to exit a plane and present to the relative wind exactly how you want to, and exit the tunnel chamber and place your self on the relative wind exactly as you want to? Same concept, different angles.

Also it is very possible to track in the tunnel and practice fall rates faster than the tunnel can go. It is even possible to experience the mushyness hill work gives you. It Just takes some creativeness and someone that can guide you well.

Im not saying that we should stop skydiving for good, but if we want this sport to improve then we have to improve. This is a great opportunity. Try it.

[quade 4]

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What difference is it to exit a plane and present to the relative wind exactly how you want to, and exit the tunnel chamber and place your self on the relative wind exactly as you want to? Same concept, different angles.

Please show me how this can be done. Video would be good. I know the wind tunnels have video, so please show me some video of exit practice in the wind tunnel.

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Also it is very possible to track in the tunnel and practice fall rates faster than the tunnel can go. It is even possible to experience the mushyness hill work gives you. It Just takes some creativeness and someone that can guide you well.

Again, please show me how this can be done. I'm really interested in how tracking practice is accomplished in the wind tunnel. Again, video would be good.

quade -
The World's Most Boring Skydiver

[daveb 1]

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***What difference is it to exit a plane and present to the relative wind exactly how you want to, and exit the tunnel chamber and place your self on the relative wind exactly as you want to? Same concept, different angles.

Please show me how this can be done. Video would be good. I know the wind tunnels have video, so please show me some video of exit practice in the wind tunnel.
You can practice exits, sortof, in the tunnel. It is not anything like from the aircraft, except that perhaps you are moving from non-flying to flying. I've done several types of two-way exits (cat, stairstep, compress, star, sidebody, phalanx) with one standing in the doorway in the wind, the other in the door out of the wind. I've also done a few 4ways, standing upon the wire in the wind, and transitioning to flying. Again, the only similarity I noticed was the moving from static to flying. I suspect it builds awareness more than any accurate sensation. Moreover, such techniques "teach" you to go immediately to the flat and ignore the hill (bad). But they are fun (good). ;-)

I don't have the proper video hardware to upload from VHS, or I would show you some of these "exits".

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Also it is very possible to track in the tunnel and practice fall rates faster than the tunnel can go. It is even possible to experience the mushyness hill work gives you. It Just takes some creativeness and someone that can guide you well.

Again, please show me how this can be done. I'm really interested in how tracking practice is accomplished in the wind tunnel. Again, video would be good.
Fly towards a coach standing in the doorway, or perhaps as a fly on the wall. Once he has a firm stance and hold on you, start to track. You can achieve a very good forward push and a track-like posture. It's not really tracking, but you do get the feel for what certain body positions can do.

Both of these techniques require the tunnel staff to okay you individually, and are best done with a coach. Both of these techniques have the potential for harm. Do not try these without proper coaching.

IMHO the tunnel is no substitute for jumping. It is a wonderful tool that comes close to simulating a free fall, but it is a supplement, not a replacement.

[harryskydives 0]

I'm really interested in how tracking practice is accomplished in the wind tunnel. Again, video would be good. --------------------------------------
Humm I guess a good helmet would be required.
We did a drill where one tried to slde slide and the other held a side body on them and pushed against them.

Don't run out of altitude and experience at the same time...

[kallend 2,026]

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Again, please show me how this can be done. I'm really interested in how tracking practice is accomplished in the wind tunnel. Again, video would be good.
Fly towards a coach standing in the doorway, or perhaps as a fly on the wall. Once he has a firm stance and hold on you, start to track. You can achieve a very good forward push and a track-like posture. It's not really tracking, but you do get the feel for what certain body positions can do.

IMO it's not tracking at all. You need the forward speed to get the lift. Without that how can you possibly figure out what the right body position is? The airflow in a track comes from a different direction.

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

[Bodyflight.Net 0]

[Ron 10]

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Can somebody tell me the definition of tracking, because to me, it seems it's been blurred here. Tracking is the same as Forward. The only difference between Tracking and Forward is that when a skydiver tracks, he/she positions their body in a way that they are moving head down first in a flight pattern similar to a parachute 'down and forward.' Tunnelrats learned to fly horizontally, thereby eliminating the aggressive downward slope and replacing it with a more horizontal plane of flight. Can you practice this in the tunnel? Of course you can, but will you?
Blue Skies and Fast Air,

to get a "real" track you have to gain lift from your body....To do that you have to move fast horizontally....You can't do that in a tunnel. You can move forward, but you can't move forward fast enough to gain lift...so the only way to practice that is in the air.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[Bodyflight.Net 0]

[Ron 10]

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I suppose by 'real' track you mean Skydiving Track. and the 'forward fast enough to gain lift'?? You can't be saying that you gain lift when tracking... if you are, then I still don't get it. Lift is opposing the pull of gravity, no one is accomplishing that on a skydive at any time.. you are always falling.

Yes I am saying that...You can gain lift without actually climbing. You instead will just use that lift to slow the descent rate..Think of a glider..It still has lift even though it can't on its own gain altitude. Hell think wingsuit. They gain lift, and you can't practice that in a tunnel.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[rehmwa 2]

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Lift is opposing the pull of gravity, no one is accomplishing that on a skydive at any time.. you are always falling.

[kallend 2,026]

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to get a "real" track you have to gain lift from your body....To do that you have to move fast horizontally....You can't do that in a tunnel. You can move forward, but you can't move forward fast enough to gain lift...so the only way to practice that is in the air.

[rehmwa 2]

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Lift is DEFINED as the vector component of force perpendicular to the free stream direction (which, roughly translated, is the direction in which you are moving

I don't think that's right, but it's been over 13 years since I got my Aero E degree. I've always thought lift was defined as opposite to gravity. However, if it's just perpendicular to the free stream, then the component of lift in a track is more than just a tiny bit as I said earlier, it's a significant component of the force acting, maybe as much a several percent. In any case, it's just vector math to prove either case.

Just thought of the glider force model - Lift has to counter the force component of weight 'perpendicular' to line of flight. The other weight component becomes the 'thrust' to counter the 'drag'. Now I'm thinking you are correct, the fixed reference frame is tied to the direction of flight, not the earth. It's a lot easier to think of the balance with that picture - you only have to break up weight into the orthogonal components instead of the other three forces......

Edit: Of course, to generate lift, you still have to counter the rotation component

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[Ron 10]

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1 - Then a glider wouldn't work in this discussion either. But it does.

2 - In a good track, you can generate a flow of air 'around' the body in addition to 'against' (against). The flow around can produce a force component which has a vector pointing in the opposite direction of weight (in a steep dive, it's a very small component, also, as a wing, we have a very small span - as in span, camber, chord). But that's still lift by any definition. Of course, the big player is drag which is that 'against' force. I say any skydiving model could be fully done with only drag and ignore the lift components, though. Except for maybe full tracking modeling

Yeah all that he said!!!! Why do you and Kallend always make me feel stupid when I come up with good examples...and then you guys get all technical on my ass? Geeze you are gonna give me a complex!

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Hey Ron - Tunnel camp last weekend. I understand ALL of what you meant in the mantis postings. THANKS for the discussions and things to think about. I worked quite a bit of fine tuning.

Ok I feel better...I may not say it like "The flow around can produce a force component which has a vector pointing in the opposite direction of weight"...but at least ya got it!

And I'll help anytime I can.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[rehmwa 2]

I just make up stuff as I go.

If you can't dazzle them with brilliance, baffle them with bullshit.

Nerds unite for better skydiving!!

Edit: Before Kallend jumps in so I can avoid the precise back and forth stuff......., I looked up the classic definitions of the 4 forces. Lift = perpendicular to relative wind/line of flight; Drag = right angle to rw/lof; weight = down, thrust = direction engine points ( no kidding). I got the thrust component wrong. Now I remember breaking up weight and thrust during school for this stuff but never having to mess with lift and drag........

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[kallend 2,026]

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I just make up stuff as I go.

If you can't dazzle them with brilliance, baffle them with bullshit.

Nerds unite for better skydiving!!

Edit: Before Kallend jumps in so I can avoid the precise back and forth stuff......., I looked up the classic definitions of the 4 forces. Lift = perpendicular to relative wind/line of flight; Drag = right angle to rw/lof; weight = down, thrust = direction engine points ( no kidding). I got the thrust component wrong. Now I remember breaking up weight and thrust during school for this stuff but never having to mess with lift and drag........

Good trackers can achieve 1:1 without a wingsuit. That suggests they are developing a hell of a lot of lift just from their body position. No way you can simulate that in any current wind tunnel.

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

[daveb 1]

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Good trackers can achieve 1:1 without a wingsuit. That suggests they are developing a hell of a lot of lift just from their body position. No way you can simulate that in any current wind tunnel.

Has anyone actually measured/demonstrated that real lift is occurring, instead of simply a slower fall rate with a horizontal component? It seems dubious to me that real lift is involved, since that would involve significant airflow over the body from the horizontal position, yet when the track starts out, there is (hopefully) zero horizontal component. But I've seen good trackers get this 'lift' immediately upon starting their track; and by extension, they should receive more and more lift as they build up horizontal speed, but this does not seem* to be the case -- it seems they descend at a constant rate, just a slower rate than before the track. Conversely, the flare at the end of the track should -- if lift was the reason for the reduced fallrate -- result in a marked increase in fallrate; again, not something that I've noticed (but then I'm usually saving my life at about this point ;-).

*seems = my limited experience. Does anyone that can track really well, and own ProTrack+JumpTrack confirm that they really do fall slower the further into their track (i.e. the faster their horizontal component) they progress? And the increased fallrate at the flare-point, just prior to deployment?

[kallend 2,026]

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Good trackers can achieve 1:1 without a wingsuit. That suggests they are developing a hell of a lot of lift just from their body position. No way you can simulate that in any current wind tunnel.

Has anyone actually measured/demonstrated that real lift is occurring, instead of simply a slower fall rate with a horizontal component? It seems dubious to me that real lift is involved, since that would involve significant airflow over the body from the horizontal position, yet when the track starts out, there is (hopefully) zero horizontal component. But I've seen good trackers get this 'lift' immediately upon starting their track; and by extension, they should receive more and more lift as they build up horizontal speed, but this does not seem* to be the case -- it seems they descend at a constant rate, just a slower rate than before the track. Conversely, the flare at the end of the track should -- if lift was the reason for the reduced fallrate -- result in a marked increase in fallrate; again, not something that I've noticed (but then I'm usually saving my life at about this point ;-).

*seems = my limited experience. Does anyone that can track really well, and own ProTrack+JumpTrack confirm that they really do fall slower the further into their track (i.e. the faster their horizontal component) they progress? And the increased fallrate at the flare-point, just prior to deployment?

What do you mean by "real lift"? Lift is certainly developed in the sense used in aerodynamics. I am not aware of another definition.

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

[daveb 1]

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What do you mean by "real lift"? Lift is certainly developed in the sense used in aerodynamics. I am not aware of another definition.

More than a negligible amount of lift.

[quade 4]

L = 1/2rhoV^2 * Cl * A

There is no "negligible" amount of lift when it comes to skydiving speeds and density altitudes. It's all lift. Otherwise you'd never be able to even turn a single point.

The physics professor is correct . . . ya can't track in any of the current wind tunnels.

quade -
The World's Most Boring Skydiver

[daveb 1]

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L = 1/2rhoV^2 * Cl * A

There is no "negligible" amount of lift when it comes to skydiving speeds and density altitudes. It's all lift. Otherwise you'd never be able to even turn a single point.

The physics professor is correct . . . ya can't track in any of the current wind tunnels.

I don't dispute the infeasibility of tracking in one of the current wind tunnels. And I'm not about to argue physics with a prof. I would appreciate an answer in layman's terms to my query earlier about fall rate vs lift, because that formula doesn't really 'splain it to me. I'm even more confused by the claim: lift is required to turn points?

[quade 4]

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I'm even more confused by the claim: lift is required to turn points?

Not a claim, it's a fact.

There are some high-priced people that give advice in the wind tunnels that say things like, "It's all just pushing air" and if you want to subscribe to the Newtonian model for the theory of lift, that works just fine. I've got no problem with that whatsoever. Whatever enables you to understand the basics -- fine by me -- I'm not going to complain unless you want me to teach you how to fly an airplane or want to get into a deeper discussion about how canopies work.

The fact is, however, aerodynamically, we're still talking about lift and lift can actually take place in a number of directions simultaneously. For instance, an airplane's wings create lift, that's kind of obvious, but so does its propeller. We normally call it thrust, but in fact, it's just lift turned on its side and in the direction of where we generally want to go.

When you twist your body, stick out your legs or tilt your shoulders your body moves because of an aerodynamic reaction to the air moving past you.

If four astronauts in space tried to turn points, it simply wouldn't work. No air, so no air moving past them, so no movement based on the body flight techniques common in skydiving.

quade -
The World's Most Boring Skydiver

[quade 4]

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I would appreciate an answer in layman's terms to my query earlier about fall rate vs lift, because that formula doesn't really 'splain it to me.

It's late tonight and I've got to try to think of a simple way to explain it to you. Lemme sleep on it and I -will- get back to you.

In the mean time, just for kicks, go rent the Wizard of Oz and pay attention to what the Scarecrow has to say to the Wizard after the Wizard gives him the diploma.

Seriously.

quade -
The World's Most Boring Skydiver