A drag issue : to bungee wings or not to bungee

[Blackwood]

Because both water and air are fluids - but they have wildly different fluid properties in terms of say, viscosity.

+ the fundamental difference between liquids and other fluids (like air, for example): compressibility.

 

[PfcAJ]

There's a difference between forcing air out and rapidly forcing all the air out. Bungees also trap air, remember?

All things equal, they are going to force more air out faster than a non-bungeed wing. Why make a bad situation worse?

The issue is twofold. The force air out (a real big problem when your tanks are full) and inhibit complete emptying of the wing (this is a problem if your tanks are empty status post gas failure).

So, use your redundant bouyancy?

I have to use it LESS if I can maintain a reasonable amount of air in my wing. While doable, using a DS for buoyancy isn't great (even more-so if you need a lot of lift from it), and having a 2nd bladder is problematic for reasons stated elsewhere. This isn't the time or place. Once again, why make a bad situation worse?

Don't you wear fins?

I do wear fins, and I also understand that I could drop a considerable distance in a short amount of time. I'm neutral (for the most part) at all phases of a dive. A sudden and dramatic loss of gas from the wing is certainly going to cause me to sink a bit... Once again, why fin a whole bunch if I don't have to?

 

[lamont]

So we agree I'm not overweighted, great




No-one is telling you to switch. In fact quite the opposite, if you have factual reasons not to use a bungee wing in non-OH, let's hear them




At least two other people have implied it will in this thread

I have no evidence that a bungee wing should not be used. I also have no evidence that a type-r sticker on a Ford escort increases drag, but its still dumb.

And the other people on this thread claiming you will die aren't my problem
, nothing I can do about that.

 

[The Chairman]

A bungee wing has no advantages when there are alternatives out there, has well documented potential downsides, and really serves no purpose.

Documented Advantages:

• Ultra stable (compared to a non-bungeed wing)
• Deflation is easy!
• Wonderful profile
• Keeps elitist divers from ruining your dive by tagging along! :mooner:

"Well documented potential downsides" I call Ultra Shenanigans. That's like saying that the ring you gave your betrothed has "Genuine Faux Diamonds".

The ONLY documented "downsides" in this thread are hypothetical: not potential. They exist only in your mind and not in reality. The lady who died, also had a tank, a regulator, fins and a mask. Saying that the bungeed wings killed her is to suggest that the other items she was diving with also killed her. Preposterous to say the least.

If nothing else, this thread is making me want to go out and buy an OMS bungeed wing. Do they come in a singles size? I bet they'll be great side mounting.

 

[Tortuga68]

the difficulty in orally inflating them at depth

Are you speaking from personal experience? At what depth do you find it difficult to exhale?

All things equal, they are going to force more air out faster than a non-bungeed wing

Agreed. But how much more, 10% 50% 200%? I don't know actually, would be an interesting experiment

They... inhibit complete emptying of the wing (this is a problem if your tanks are empty status post gas failure)

It's only a problem if you set your rig up to need zero air in the wing with empty tanks. Can you vent 100% of the air from your wing? If you orally deflate it after venting do you get any more air out?

I have to use it LESS if I can maintain a reasonable amount of air in my wing. While doable, using a DS for buoyancy isn't great (even more-so if you need a lot of lift from it)

Agreed. A good reason not to use a DS as redundant buoyancy

I do wear fins, and I also understand that I could drop a considerable distance in a short amount of time. I'm neutral (for the most part) at all phases of a dive. A sudden and dramatic loss of gas from the wing is certainly going to cause me to sink a bit... Once again, why fin a whole bunch if I don't have to?

Again, how much faster/more air will you lose becauise of the bungees? You'll have to fin either way, how much more will you have to fin with a bungee wing? Given that - by Tobin's calculations - I only need to inflate my wing to 25% of its capacity, how much additional force will the bungees be exerting compared to the 5-15 ATA than the water column is adding to the outside of the wing? I know they're easier to vent at 0-30m, but at depth what effect are they having?

I have no evidence that a bungee wing should not be used

Someone sig this

 

[PfcAJ]

Documented Advantages:

• Ultra stable (compared to a non-bungeed wing)
• Deflation is easy!
• Wonderful profile
• Keeps elitist divers from ruining your dive by tagging along! :mooner:

"Well documented potential downsides" I call Ultra Shenanigans. That's like saying that the ring you gave your betrothed has "Genuine Faux Diamonds".

The ONLY documented "downsides" in this thread are hypothetical: not potential. They exist only in your mind and not in reality. The lady who died, also had a tank, a regulator, fins and a mask. Saying that the bungeed wings killed her is to suggest that the other items she was diving with also killed her. Preposterous to say the least.

If nothing else, this thread is making me want to go out and buy an OMS bungeed wing. Do they come in a singles size? I bet they'll be great side mounting.

Netdoc; a Descartes for our times. :thinking:

 

[PfcAJ]

Tortuga, a DS is more great (since I used less great, before) than dual bladders, though.

I just wanted to throw that in there so it didn't look like I agreed with you on something

 

[danvolker]

Interesting story - albeit unrelated to bungees - thanks for sharing it

Although I would have thought the moral was 'don't blow and go' rather than 'don't use a massive wing'

If you were trimmed out at the time rather than "FULLY INFLATED", wouldn't you just disconnect the inflator hose?

I dumped all to be heavy, as I swam over and grabbed him...the English guy could not get his valve to work, the issue being -- not more air being added by the high pressure hose, but rather, a failure of his ability to dump....I did not have time to move his body around enough to get to a valve...he had his hand on the pull dump on the bottom of his bc, but this was not working --- way before you could actually do anything, we were at the surface...Remember, he had the inertia of a full speed ascent from around 250 feet ( a deck) to 120 to 100 feet where I grabbed him...

Yes, this hurt the mojo for the thrill of Blow and Go, but it is also on point with the huge overkill on high lift wings.
If I am using my Halcyon 18 lb lift single tank wing, I could inflate it to max at any depth, and my rise to the surface would be easy to control..plenty of time to pull a inflator hose off, meanwhile fighting the ascent with either a horizontal position, or downward swimming. I can pull an 18 pound anchor off the bottom when freedivng ( no bc), but I could not do anything to a 100 pound anchor....ie., On doubles, I would be fine with 40 to 50 pounds of lift, because I should not have much over 30 pounds of excess lift no matter what stupidity I am involved with. ..I could effect the 30 pounds of lift force....I could have no effect on the lift of a monster 120 lb lift wing if it fully inflated. How far could it go before you could disconnect the inflator? That would be the big question, different for each person by reaction time, if they had something in their hands at the time, task loading, etc.
Limit the excess lift, and you limit the risk of insufficient time to fix the runaway inflation problem.

The bungees were a way to make a huge monster wing dive smoother. But, they allowed a diver to use a wing volume larger than what they should be using( dealing with one problem by adding a new problem) , and in some instances, when the diver really needed the ridiculous amounts of lift these monster wings could deliver, the bungee mechanism "could" prevent the wings from filling, and the whole "more is better idea" went down the toilet.

Better to limit how heavy your backgas and stages will weigh, avoid large bouyancy swings caused by thick wetsuits, and use the wing that lifts you fine, but not ridiculously overdoes it. Trim is much better, the diver is slicker in the water with less drag, and the danger of runaway inflation is smaller by far. Without the bungees, there is no restriction to filling the wing to full if needed...and even a puncture will not be likely to create much of an issue.
For 99% of the divers here doing recreational, this is of almost zero practical value, except for the part about how you solve things.....

Regards,
DanV

 

[Garth]

air trapping does not occur anymore! Repeat: air trapping does not occur anymore! isn't that wonderful news.

I'll say it for the 10th time.

If you place the bungees from the eye of the wing forward so that the wing collapses towards your body away from the tank the back of the wing does not taco around the tank and is perfectly flat as if you were not using bungees. amazing. I need to take a photo and post here. Anyway. you'll see this weekend when I post.

 

[cool_hardware52]

air trapping does not occur anymore! Repeat: air trapping does not occur anymore! isn't that wonderful news.

I'll say it for the 10th time.

If you place the bungees from the eye of the wing forward so that the wing collapses towards your body away from the tank the back of the wing does not taco around the tank and is perfectly flat as if you were not using bungees. amazing. I need to take a photo and post here. Anyway. you'll see this weekend when I post.

Take your bungeed wing set up any way you choose. With the wing / diver horizontal and near the surface let the bungees deflate the wing as much as they can, hold the opv open, raise the inflator etc. etc.

Now remove the wing from your rig and throw it in the water. Does it float? Does it require ballast to sink it? Every bungeed wing I've tested traps gas in the lumpy convoluted humps left between the shock cords.

Tobin