A drag issue : to bungee wings or not to bungee

[TSandM]

If you ever paid attention to how it's done, you slow down as you move your feet forward because guess what? There's more drag!

If you're slowing down during the loading phase of the kick, then your ankles are stiff. I found that out, working in the pool. If the fins are perfectly oriented so that they present minimum profile to the water (which they will pretty much do by themselves if your ankles are relaxed) you don't slow down perceptibly while loading. If your ankles are stiff, you can slow down a lot.

 

[Lenaxia]

It's not nitpicky in the slightest. It's fundamentally different. Constant speed (which seems to be what you are describing with your flutter kick discussion) = zero accereration, so if drag were proportional to the square of acceleration, that would mean that there's no drag once you reach your constant speed (0^2 = 0). That's obviously wrong. Once you're cruising at a constant speed, drag = kick force.

In any case, my question was intended as: what does kick type have to do with this discussion?

Your post seemed to suggest that bungeed wings don't make sense for frog kick but they do for flutter kick, or something like that. It just seemed like an odd addition to the thread.

FWIW, I agree. Whether they create more or less has yet to be answered, but more than likely bungees will have an insignificant effect on drag.

I suppose it was a somewhat round about way of geting to the point, but I was trying to illustrate that those that worry about bungees affecting drag have more significant inefficiencies to worry about than a few pieces of elastic on their wing.

 

[OneRestlessNative]

For all of those who so are ultra worried about drag and minimizing it, might I suggest this for future dives.... At least it will be a sure fire way for the rest of the non-believers to steer clear and give you all the room you need to jettison through the sea at max efficiency.

 

[Blackwood]

I suppose it was a somewhat round about way of geting to the point, but I was trying to illustrate that those that worry about bungees affecting drag have more significant inefficiencies to worry about than a few pieces of elastic on their wing.

Definitely. I'm not going to go back and re-read the thread, but I don't think the majority of the "anti-bungee" posts hinge on some perceived increase in drag.

The summary of major complaints seems to be:

1) Potentially harder to inflate,
2) Potential catastrophic deflation in the instance of certain wing failures,
3) Potentially a snag hazard,
4) Design intent seems to be compensation for wings that are much larger than is necessary (in other words, get a properly sized wing rather than fixing an oversized wing)

I won't take a stance on any of those issues.

 

[The Chairman]

1) Potentially harder to inflate,
2) Potential catastrophic deflation in the instance of certain wing failures,
3) Potentially a snag hazard,
4) Design intent seems to be compensation for wings that are much larger than is necessary (in other words, get a properly sized wing rather than fixing an oversized wing)

Yeah, the biggest opposition is based on three hypothetical situations (catastrophes in search of reality) and a supposition (ascribing intent where there is none). In fact it appears that the entire thread was predicated on a mythical event that provided us with absolutely no data: just a lot of imaginary observations fueled by a desire to either belittle or appear to be intelligent.

 

[OneRestlessNative]

I wonder if this diver chose a non-bungeed wing to reduce drag and entanglement hazards?

 

[Gombessa]

I wonder if this diver chose a non-bungeed wing to reduce drag and entanglement hazards?

As long as we're playing this game, to me it's more likely that he chose a bungeed 94lb wing because he automatically assumed he'd need that much lift to support all those slung bottles?

 

[formula1mb@aol.com]

I read somewhere on another thread that during the next GUE meeting in Mexico, they will be discussing sidemount diving.

Wonder if they do start utilizing sidemount, is GUE going to be using bungees and suddenly it will be 'blessed' ? Or do they have another design for sidemounting?

 

[jtivat]

I like my BC to deflate faster. I don't add air willy nilly to my wing and when I dump, I dump most of the air because I'm ascending. I'm weighted well enough that if I have air in my BC at all, its a small amount and my lungs provide enough lift capacity in and of themselves for more then adequate attitude control.

I really don't get why any divers are crying about hydrodynamics or any of that other stuff. Frog kick is extremely inefficient from a hydrodynamic point of view. If you ever paid attention to how it's done, you slow down as you move your feet forward because guess what? There's more drag! Then your quick acceleration as you snap your feet back? Well guess what? Drag is squared proportionally to acceleration. That's even more drag that you are generating.

Slow mod-flutter? No acceleration drag, no excess drag from your feet spreading out and fins kicking out to the side. Does it take more energy? No, it doesn't, if you're moving at the same average speed as you were doing with your frog kick, you're using less energy, thus less air.



If your lung capacity isn't enough to overcome the bungees on your BC, I question whether you're fit enough to be diving. My Zeagle Brigade (Escape wing) has bungees but they aren't all that strong or tight; I have no problem inflating my BC orally after a hard workout (yes I have tried). Not only that, the bungees are only on the underside, thus don't trap air when I'm emptying it.

Both problems solved in my case, and the bungees provide the added benefit of emptying my BC faster. They also don't provide more turbulence because they are UNDER the wing and thus the upper surface of my wing is still smooth and the under surface is already turbulent from the water passing over and around my head and shoulders.

So what's the problem?

I proper frog kick will reduce your SAC.

Well in most my diving we are talking double steels with deco bottle and 23LBS. to 35LBS. of gas, would love to see you swim that around with your lungs.

 

[PfcAJ]

I don't know what they will talk about at Conference in regards to sidemount, but I think we can all appreciate the difference between the bungees we see here Nomad BC System by Dive Rite - Dive Gear Express and here OMS Buoyancy Control Systems - Buoyancy Compensator ( BC's ) http://www.OMSdive.com.

And NetDoc, you see real caught up on these "hypothetical" situations that don't really happen. Some dude on another forum (dirx, for the interested reader) had his corrugated hose completely detach on a dive. I've personally had a hole in my wing before. I'm reasonably sure that someone who posts on this board frequently had an OPV separate. These are real things. If a bungee is constricting your wing, wouldn't it also force air out, making a bad situation worse?

Since you have a bungee wing, and I have a pool and two sets of 104s and 2 backplates, lets have a little test, we can even video it and show everyone. Bring your wing to mi casa, and well try it out in the water and see what happens. We can unscrew the OPVs, pull off the corrugated hoses (I think we'll skip on putting a hole in them) and we'll just see what happens. Fair? If I'm so wrong about this, it should be a slam dunk for you.