"Wing Constants" How do manufacturers define/model their wings?

[lowviz]

Just finished a sidemount trim clinic. A Long Island, NY (USA) instructor just dialed me in on my sidemount gear. The feeling of just hanging there, in trim, without any effort on my part was transcendental... Thanks, Danny! Seriously, man!

Why can't I do this in backmount DOUBLES? Word on the street says I can. Just pick the right agency, get mentored before you show up, and all is good. Uh, step one is to find an unpaid mentor of completely unvetted abilities and or teaching skills to dial me in? Pass. Who are you kidding?

Epic fail on fundamental principles. Job one is to hang in trim. Show me an agency that offers a formal course/clinic that promises just that. Come to us as a scuba dolt and leave as someone who can hover in trim. Anyone? But how hard is that?

Why is that funny? Unless you can hang in trim without effort, you are screwed with respect to absolutely anything and everything more advanced. You are set up to waste endless funds seeking advanced skills that remain beyond your current level of physical abilities. Resolve and determination will not garner success, they only will only magnify your abject frustration.

So, hanging in trim without doing anything is physics. Nothing more. Let's do that.

You can be neutral in any sort of trim. The lead/ballast that is needed determines neutrality. Trim is another issue altogether. Thought experiment: take a pool noodle and put two weights on it that will cause it to just sink. Does it seem logical that simply adjusting the placement of those weights will cause it to hover in any trim you desire?

So back to wings. We design a scientific rig of a mass similar to a diver that can be zeroed and add a wing. Add weights, inflate wing to exactly counteract them. Slide weights until rig is exactly horizontal. You can now determine the exact center of rotation of the wing at various inflations (pounds lift). You have defined the wing. You can model it.

Define the diver. This was quite difficult and very imprecise until I added the backplate to what is the diver. Now I can find and reproduce my center of rotation to within a half of an inch. Tanks and reg sets are easy. When all of the centers of rotation (moments) cancel, you are in trim. A simple buoyancy correction will then allow you to hang in trim. Any tanks, any exposure gear, any wing. Yes, some combinations are "undiveable".

Best part of all this: If you aren't in trim, you know it is YOU. Contorting oneself can counter a lot. Maddening. Nice to start from balanced and trimmed gear, no?

Why does one have to figure this out for oneself? Shouldn't this be a formal course? Or is it just so stupidly easy and obvious that it doesn't need to be taught at all?

What is really useful is to match your wing's progressive shift to counter your cylinder's...

So, bottom line, How do you manufacturers "define" your wings? Or do you just make something that looks cool and let advertising run with it?

https://vimeo.com/131498481

 

[tbone1004]

most wings have 3 mounting holes, this allows you to adjust the wing for "you" in relation to the tanks and backplate and what not. The problem is not everyone wears their plate in the same spot, not all plates are identical, not all tanks are identical *remember that an AL80 has a very different trim profile than a LP104*. Wings have to be designed around loose parameters so that nothing is wildly out of control, but can be adjusted within reason. The position of your legs controls up to a few pounds of trim weight, especially in doubles where you are usually wearing heavy fins. If you think about it, a set of Scubapro Jet fins is a few pounds negative, you are now moving this close or father aware from center which is a radical change in the moment arm.

Now, also think about this. If you are diving a balanced rig, which you should be or at least close to it, you are only trying to counter the weight of the gas in the tanks, you aren't using the wing as a trim device, or at least shouldn't be. You should have the rig positioned so that with no air in the wing you are able to get trim and the wing will provide a lift point that is centered to the tanks, nothing to do with the diver. This is the main issue with sidemount wings that have lift at the shoulders. If you are diving properly, the first stages are under your arm pits so why would you need any lift above that?

Your issues in backmount likely have nothing to do with the wing, but more with having the rig positioned properly, and trimming the rig on its own instead of blaming the wing. I.e. same reason why some wetsuit sidemount divers have trim weights on their shoulders, many find a 2lb tail weight on doubles to be exactly what they need to trim them out properly but few use them.

 

[lowviz]

most wings have 3 mounting holes, this allows you to adjust the wing for "you" in relation to the tanks and backplate and what not.

Yes, so my reference point is always the bottom most hole on the wing.

The problem is not everyone wears their plate in the same spot, not all plates are identical, not all tanks are identical

Frog position is different than flutter, hand position counts...

Not everyone wears their plate in the same spot and not everyone has the same buoyancy characteristics. But, most everyone puts their plate on in the same place each time. Trimming out is a personal thing. AND it depends on what you are wearing, can lights, on and on. But it is easily definable if you know the underwater weight and center of rotation of everything you add.

*remember that an AL80 has a very different trim profile than a LP104*.

Yep, my twin LP 72's don't act at all like my dual HP 119's. But I know their underwater weight and center of rotation.

Wings have to be designed around loose parameters so that nothing is wildly out of control, but can be adjusted within reason.

I wonder about that. If so, then wouldn't there be strongly forward buoyant wings and strongly rearward buoyant wings to choose from?

The position of your legs controls up to a few pounds of trim weight, especially in doubles where you are usually wearing heavy fins. If you think about it, a set of Scubapro Jet fins is a few pounds negative, you are now moving this close or father aware from center which is a radical change in the moment arm.

Yep, all part of the system. But wouldn't it be nice if everything were adjusted so I could achieve balance with my jets in perfect frog position? I can always bend my knees to adjust trim...

Now, also think about this. If you are diving a balanced rig, which you should be or at least close to it, you are only trying to counter the weight of the gas in the tanks,

Yes, this is what this is all about. A balanced rig that you can assemble on paper and it magically works underwater.

you aren't using the wing as a trim device, or at least shouldn't be. You should have the rig positioned so that with no air in the wing you are able to get trim and the wing will provide a lift point that is centered to the tanks, nothing to do with the diver. This is the main issue with sidemount wings that have lift at the shoulders. If you are diving properly, the first stages are under your arm pits so why would you need any lift above that?

Bolding is mine, words are yours. I couldn't agree more. But knowing where that point is for both the tank and wing is really good to know. Now add the diver in his/her underwear of choice and drysuit. Doing so messes up the wing/tank balance. However, you can move either the wing or tank to counter the diver's characteristics.

Your issues in backmount likely have nothing to do with the wing, but more with having the rig positioned properly, and trimming the rig on its own instead of blaming the wing. I.e. same reason why some wetsuit sidemount divers have trim weights on their shoulders, many find a 2lb tail weight on doubles to be exactly what they need to trim them out properly but few use them.

The wing is nothing special. This is all about balancing a system and the wing is just part of it.

However, the wing is a rather difficult piece to define. Thus my post.

 

[tbone1004]

so how do you propose this is done? With the three holes, you have the option to adjust for tank trim. Your 119's should behaving better with the wing more centered or biased to the bottom, but the 72's will play nice with them on the bottom hole because they need more lift up top.

The point of my post is that the wings are there to keep the rig balanced, not you, and they do a pretty good job at it. The plate helps to offset the weight of the manifold and regulators so you don't want all of the lift up top, and you can't put it up there because there isn't enough room for the lift required. Now add in the fact that their trim characteristics change when the tanks get empty, so there is no real way to design a wing to that degree of precision because there are too many variables involved.

I can hover motionless in doubles, if you're good, your body compensates for it without thinking about it and it can counter quite a bit subconsciously if you have trained it to do so. The wing is pretty low on the list of variables to change to achieve that level of trim. Rig position on your back first, fins second, trim weights third, then if it is still really bad you look at the wing.

Now, that isn't the end of the story though because wings behave in certain ways.
https://www.deepseasupply.com/index.php?product=1325
This design will bias the air to the center of the wing because that is the highest point on both sides.

SCUBA Diving Equipment for Technical, Sidemount, Rebreather, Wreck and Cave Diving: Dive Rite, Inc - Product Catalog - Rec Series
This wing will bias the air towards the butt because that is the highest point. Not a good choice for AL80's, LP72's, Faber 85's, etc that are butt light when empty, not a bad choice if you're diving in a wetsuit though where your legs will be somewhat heavy.

So certain wings do have certain design considerations, and you should choose accordingly, but as a whole you can't put a lot of real math to the puzzle because the variables can't be defined during the design process

 

[PfcAJ]

So are you guys using a different wing and or readjusting your harness every time you use a different set of tanks? Or doing that every time you use a deco bottle? Or a stage? Or two? Or a bigger or smaller can light? Different undergarments?

the diver dives the gear, not the other way around.

 

[lowviz]

... but as a whole you can't put a lot of real math to the puzzle because the variables can't be defined during the design process

I believe that all the big ones can. I have a rack that bolts onto my 10# custom Fred Tagge backplate. So I get into frog position under a half inch stainless steel bar that is held down with two 50# plates. No air in my drysuit, shop vac on the exhaust port. Find my center of rotation with nothing in my drysuit.

I know how much weight will exactly sink me. Add five pounds, shoot five pounds of lift into my drysuit. Back on the rack, now I can define the bubble.

I disagree. It is all simple physics. Everything can be determined to a reasonable degree without all that much effort.

 

[tbone1004]

it is all simple physics for YOU with THAT gear. It is impossible to define for all divers in all exposure suits, with all tanks, with all manifolds, with all regulators, with all fins, with all can lights, *this can go on for quite a while btw*. The point is what AJ said is exactly right, it is literally impossible in doubles to do this process from a manufacturing standpoint, all they can do is make it close enough with no egregious errors. I.e. don't dive a Dive Rite Nomad wing with double AL80's because you'll be boring a hole into the sand. With most setups, with most wings, a good diver can trim the rig out without thinking about it. You can go and move AJ's canister to his butt, swap AL80's for 104's and back again, change Apeks DST's to little Apeks flight first stages *this one is surprisingly large actually about 3lbs*, and change Jet Fins for Avanti Quattros and within 10 seconds his body will naturally adjust to maintain trim, *never met AJ, I'm sure we'll try to kill each other then buy each other a beer afterwards when we do, but he's a good diver and that's what matters*. You can do the same to me, I've had it done. Backmount is a VERY forgiving system compared to sidemount when it comes to trim.

With sidemount, very little of what you had done is due to the wing, sorry but I guarantee you that whatever manufacturer you bought from didn't go through all of the math for the wing design. Most of trim in sidemount is positioning the tanks themselves. You can't do that in doubles because you have to be able to reach the valves so you go as low as you can comfortably reach, so you adjust in other ways. Conveniently in backmount you are also biased to trim head down, which means that you can extend your legs ever so slightly and increase that moment arm and bring yourself back to flat. In sidemount however you have a bias to be foot heavy, which is very difficult to compensate for because your arms don't weigh all that much. If you have a wing like the stock SMS100 or the Nomad, they have too much lift in the shoulders which makes this problem worse, they have now fixed most of that, but it makes for an exaggerated problem because now you are fighting the wing. This is very uncommon in backmount where you are normally fighting a fixed weight up towards your head instead of a variable one that is pulling on your hips.

 

[lowviz]

So are you guys using a different wing and or readjusting your harness every time you use a different set of tanks? Or doing that every time you use a deco bottle? Or a stage? Or two? Or a bigger or smaller can light? Different undergarments?

the diver dives the gear, not the other way around.

You guys (being me) are indeed diving a huge collection of gear. Double 72's, 100's, 119's, and 120's. Somewhere around seven different wings including a monster DIR wing. Yep, it's DIR. Says so in blue. Wetsuit, two very different drysuits. Three backplates, two custom (10#SS and 3#AL) and one OMS. Stage bottles are 40's, travel bottles are 80's, pony is a 19. Monkey rig.

The GUE un***k yourself and stick with a working rig just doesn't apply here. I enjoy diving a collection, sometimes I dive just to mess with gear, mostly I dive to forget about gear (and everything else) and enjoy being underwater.

... The point is what AJ said is exactly right, it is literally impossible in doubles to do this process from a manufacturing standpoint, all they can do is make it close enough with no egregious errors.

I see that, and near the end of the dive it almost doesn't matter what wing you are wearing.

I.e. don't dive a Dive Rite Nomad wing with double AL80's because you'll be boring a hole into the sand. With most setups, with most wings, a good diver can trim the rig out without thinking about it.

Yes and no. I can come up with a couple of bears.

You can go and move AJ's canister to his butt, swap AL80's for 104's and back again, change Apeks DST's to little Apeks flight first stages *this one is surprisingly large actually about 3lbs*, and change Jet Fins for Avanti Quattros and within 10 seconds his body will naturally adjust to maintain trim, *never met AJ, I'm sure we'll try to kill each other then buy each other a beer afterwards when we do, but he's a good diver and that's what matters*. You can do the same to me, I've had it done.

Ha! No problem. I like a spirited discussion. BTW, thanks for several insights along the way.

Backmount is a VERY forgiving system compared to sidemount when it comes to trim.

I find the reverse to be true. Unless you mean change in trim with respect to tank position, then maybe yes. But once dialed in, I find that sidemount is ever so much more stable.

With sidemount, very little of what you had done is due to the wing, sorry but I guarantee you that whatever manufacturer you bought from didn't go through all of the math for the wing design. Most of trim in sidemount is positioning the tanks themselves.

Can't argue that.

You can't do that in doubles because you have to be able to reach the valves so you go as low as you can comfortably reach, so you adjust in other ways. Conveniently in backmount you are also biased to trim head down, which means that you can extend your legs ever so slightly and increase that moment arm and bring yourself back to flat.

Yes, my drysuit and heavy undergarments do limit positioning. Gloves don't help either.

In sidemount however you have a bias to be foot heavy, which is very difficult to compensate for because your arms don't weigh all that much.

Fixed that by going to DR fins from Jets.

If you have a wing like the stock SMS100 or the Nomad, they have too much lift in the shoulders which makes this problem worse, they have now fixed most of that, but it makes for an exaggerated problem because now you are fighting the wing. This is very uncommon in backmount where you are normally fighting a fixed weight up towards your head instead of a variable one that is pulling on your hips.

Interesting. I'll watch for that in sidemount as my tanks drain.

Thanks

 

[tbone1004]

backmount being forgiving is because of the location of the weight and all of that it is much easier to find "good trim" in backmount without screwing with gear, point was to emphasize that within reason, you can make just about any change to a good divers rig, and they can trim it out. You can take the best sidemount divers out there and do something as small as change their fins from Dive Rites to Hollis F1's, and they're f*cked because no amount of positioning can change the fact that you just put 4lbs of weight on their feet and they have no ability to counter it without trim weights up front. As seen by you switching from Jets to Dive Rites, which is exactly what I do and quite a few others. Backmount the fins help, and might be the difference between your legs being perfect 90* or slightly obstuse at the knee, but in sidemount, the wrong fins change it from "I can hover motionless", to "not a prayer"

 

[lowviz]

OK.

In all fairness, I have to give you that one...