Wing Drag

[tbone1004]

I've had BC's break in both locations. WATER PRESSURE will force the air out of a BC bladder.. don't be ridiculous..

that statement is ridiculous. Water pressure can only push it out if the opening is on top. If the corrugated hose goes, the wing will still hold air as long as you are head down. Same if the opv goes, it will still function normally as long as the hole doesn't go above the bubble. Bungees increase pressure on the bubble and actually squeeze it, the buoyant forces from the air pressure in the wing will always exceed the water pressure *meaning that while the bubble may get smaller due to increased pressure, the water pressure can't push the bubble down*. If your statement was true we wouldn't be able to use milk jugs as buoyancy compensators, wouldn't be able to use any sort of open bottom lift bag or SMB, and the regulators would always flood when removed from your mouth even with the mouthpiece down.

 

[ams511]

The main issue with bungeed wings is that the bungees are often used to try to compensate for wings that are far too large, like a wing that tries to be a single/doubles hybrid. If you took the bungees off the wing and just used it, you'd still have the same problems of 'tacoing' and venting that a too-large wing presents. An additional problem with the bungees is that they might make the wing a bit harder to completely vent by creating some pockets for air bubbles to accumulate.

Lots of people talk about drag created by wings that are too large; I think this is a bit overstated. The big problem with too-large wings is venting and managing the air bubble. When a wing is compact and fits snugly around the tank, the bubble stays put. Making small adjustments in buoyancy and venting are much easier.

Halo, when people think of bungee wings they are thinking of the infamous OMS wing shown above. Although they were not the only ones that tried it. However wings like these haven't be sold new in many years.

The 24 lb. horseshoe wing on the Zeagle Express Tech and the new Hollis wings are not like that. You are not going to have a problem venting them nor are they too big. Although the forcing of the air out is still and issue.

---------- Post added May 18th, 2015 at 07:58 AM ----------

Was discussing this topic with friends who mentioned they saw same thing happen to diver wearing bungee'd wing and he ended up crawling out of cave creating hot mess.

I don't fault the wing but the diver. He should have had a plan for redundant buoyancy.

 

[Nemrod]

There are elastic bands in my wife's AL Zuma. This is not a wing of course but a back inflate. The elastic helps to fold and compact the wing for packing but also keeps the profile minimal when in use diving.

I think that bungees and elastic bands could be revisited with useful results and I wish for a self fabric wing, no bladder.

N

 

[eelnoraa]

I've had BC's break in both locations. WATER PRESSURE will force the air out of a BC bladder.. don't be ridiculous..

That is not what I experience with OPV missing. I went a little head up trim, and I finished dive with air in the wing. Think open bottom lift bag. It is physics, water pressure will only force the air out of the part that is lower than the opening.

 

[cool_hardware52]

I've had BC's break in both locations. WATER PRESSURE will force the air out of a BC bladder.. don't be ridiculous..

Er, ah, well, no. With a partially inflated wing (or any flexible container) the pressure *inside* is exactly equal to the pressure *outside* Fluids flow from areas of higher pressure to lower pressure.

When there is no delta P there is no flow.


Unscrew the the OPV from a partially inflated wing and see what happens.


Your high school physics teacher has his face in in palms…..


Do you read what you write BEFORE you post it?

Tobin

 

[ams511]

Unscrew the the OPV from a partially inflated wing and see what happens.

If you are talking about on land, the wing will go flat because gravity is pushing the upper fabric down forcing the air out. If we did it in a gravity-free environment then the the air would leak out until the air pressure inside the wing and outside the wing are equal.

---------- Post added May 19th, 2015 at 02:42 AM ----------

There are elastic bands in my wife's AL Zuma. This is not a wing of course but a back inflate. The elastic helps to fold and compact the wing for packing but also keeps the profile minimal when in use diving.

I think that bungees and elastic bands could be revisited with useful results and I wish for a self fabric wing, no bladder.

N

The Zeagle Express Tech 24 lb wing, The UTD 37, and the Apeks WTX wings do not have inner bladders. There may be a few more out there that I am unaware of. What I ofter wondered is why they don't make a bladderless wing where you can zip it into a protective shell. It seems that that would be a strong wing.

 

[tbone1004]

AMS, that would be what Halcyon does. They have an impregnated fabric liner and that is inside the wing cover. Issue if you put the Apeks style is that it would A never dry, which is bad, and B be so stiff it would be a pain to deal with.

 

[JamesDownUnder]

and there are many more who swear against it. The danger of bungeeing a wing is that depending on the bungee you may or may not be able to orally inflate the wing in an emergency.

...and the bungee lashing becomes a snag point, plus a bunch of other problems. These are all good reasons I don't bungee my wings either. I was simply relaying one rationale I've heard for the practise. Understanding the benefits and risks is inherent in any activity such as diving - I wasn't suggesting it was solution for everyone or advocating the practise Thanks for the feedback though, sorry if I wasn't clear.

Personally, I found a jacket-style BCD caused far more drag and restriction of movement than my Halcyon wings. If drag is that much of a problem, hit the gym, beef up your legs, or invest in a scooter

Peace folks, and stay safe out there.



Posting from my iPad, please excuse unfortunate iCorrects.

 

[ams511]

AMS, that would be what Halcyon does. They have an impregnated fabric liner and that is inside the wing cover. Issue if you put the Apeks style is that it would A never dry, which is bad, and B be so stiff it would be a pain to deal with.

The Apeks WTX is very flexible wing and the material appears to be thicker that the inner bladder of a Halcyon. If drying is a problem the outer shell could be unzipped and removed for drying prior to storage. The stiffness of the wing is more of a function of the outer shell rather than the inner bladder. I doubt it would be any more stiff than either an Oxycheq or the second gen Hollis wings.

The advantage of the system would be you could use the bladder alone if you like and if you are diving where puncturing is a risk you can just add the shell for protection.