airguns: Sporasub One Air 2012!!!

[tromic]

That I am still not entirely sure of.

I sense from the Italian forum, that Sub Fireman is extremely respected and obviously knows a lot about pneumatic guns. Actually, more than most. Also, I have seen some truly amazing guns he has built (I think).
And perhaps it is a "forum cultural" thing, but I have not yet in the limited time I have spent on DeeperBlue seen any examples of a designer of one product being the one to point out alleged faults of a competing product.
He posts one video of what seems to be a faulty One Air and then posts a promo video about his own product, perhaps even two videos if the last one is a Evo-Air muzzled gun as well.
Again, I hope he is just doing it to be helpful and of course the circle of people who really know this stuff is not huge and some of them are bound to actually have designed some of these solutions, but it stills just feels like there should be other ways to address this.
I don't recall Tomi ever trashing a competing product. He might say he feels his is a better option but then he will go on to explain in technical details why he feels that is. What I remember is him and his son going to great lengths to tell me what other viable options were on the market.

I don't think any of the products are 100% perfect (I have only tried two), but I like both. I like the STC design (One Air) so far and have had no problems with the muzzle or shooting power at all. And I like the Evo-Air despite it being more cumbersome and I suspect much, much harder to load (I was surprised how hard my gun is to load at 17 bars and I am still not sure whether 13mm/40mm guns are just that much harder than One Airs or if it is truly the increased friction from the o-ring in the Evo-Air design).
OmerSub has taken a lot of flack for the delays and issues with the One Air. Some of it justified and maybe this is as well, maybe not, we just don't know. What I do know, is that it would be nice to hear any critique from users and not from the competing company as that makes all sorts of alarm bells go off for me - and not in regards to the One Air...

With regards,
David

David, maybe you missed my explanation:
http://forums.deeperblue.com/pneuma...ns-sporasub-one-air-2012-a-20.html#post902457

Your experience, using two guns concurrently, is very valuable, especially because they both had to have about the same loading effort. 18 bar - 13 mm piston, and 25 bar - 11 mm piston. In both cases about 24 kgf, not taking friction. Even I had not think about loading effort differences before. I believe friction force might be at least 4 kgf, otherwise O-ring would not be "movable" on higher depth (more than 20 m). I do not know the design details, like dimension of O-ring seat, so this is just my estimation.

Regarding loading the gun with Evo-Air it is not irrelevant (as Sub Fireman said) whether to omit step "1." or not. You were doing it right way. I would do it same, including step "1.".

It is true the were some problems with first version of x-power. Ive read there were some problems with Evo-Air in beginning too. My fist Tomba also had some problems. The slider was made in stainless steel and was heavy. TombaF7 had higher friction during loading.

 

[Sub Fireman]

David, I get notifications from the Forum for two years and have never tripped while reading it constantly until yesterday when my friend Tomi with which we exchange a lot of advice has informed me of this specific topic.

I showed up just declaring myself available for my own experience.

I felt it was seen that there was talk Sporasub and Evo-Air and misunderstandings on his load to write some tips to help avoid confusion.

That 's why I posted the video on its operation and Pierino 50ino the tube 13 that despite its small size has exceptional performance.

The video with the problems of Sporasub hoped would help give many signs for those who had requested and in fact I expressed myself clearly on his problem.

Now reading some work with the translator I have a feeling that this one actually is understood and I'm sorry, continue 'to read limiting my comments .... good continuation.


Annulla modifiche

Alpha

 

[popgun pete]

This stuff is not exactly rocket science, but perhaps I can explain a little more. When the spear tail is first inserted in the muzzle it will simply push water aside that is already in the muzzle until the muzzle seal takes up on the shaft body. If the spear tail has already pressed on the piston face and began moving it back even a tiny amount then the volume of trapped water inside and behind the muzzle seal will just be that which fills the available gaps around the shaft tail and in front of the piston when that contact is made. So that water volume inside the muzzle is fully "accommodated".

If the muzzle seal takes up on the shaft before the spear tail starts pushing on the piston then a hydraulic lock develops and that pushes the piston back until the spear tail takes over and fully engages the piston. Now the water inside the gun will be slightly greater than the volume accommodation provided by the physical gaps around all the parts involved, so this extra water is an "excess" amount beyond what would be the "accommodated" volume. When this sequence is reversed at the end of the shot as the piston slams into the shock absorber, that small hydraulic lock is revisited, but the spear tail jerks free of the piston giving the "excess" water another way out of the muzzle. Tromic's suggestion for the "Evo Air" was to leave the muzzle nose initially un-tightened to allow that "excess" water to escape before muzzle loading effort commenced, thus when the piston strikes the muzzle on the return trip to the shock absorber there will be no chance of that hydraulic lock momentarily occurring (unless there is a subsequent leak!). The smaller the duration of the hydraulic lock and the less "excess" water involved then the less of a problem it is.

If the muzzle seal leaks slightly after the gun is cocked then more water will be gradually sucked inside the inner barrel creating an eventual hydraulic lock inside the gun with the piston now short of the muzzle during the shot, once the water consolidates into an annular column. The fast moving piston will have shoveled the water along the inner barrel in front of it without too much resistance until the water forms a solid incompressible plug, at which time the piston is abruptly braked as the trapped water cannot escape the muzzle seal quickly enough. The high hydrostatic pressure then created inside the muzzle should blow the spear tail free of the piston, although the shaft momentum will probably jerk it free anyway. That momentary high hydrostatic pressure spike may send water back to the other side of the piston, it will be a tiny amount each time, but incremental, so you will not be aware of it for quite some time.

With Tromic's "Tomba" system the muzzle seal is blown free of the muzzle, so any trapped water has a way out, albeit restricted, provided that there is not too much "excess" water involved. With captive seals, i.e. the seal is always fixed in the muzzle, there is no way out unless the seal can move in its seat and let water get out around it.

If a vacuum barrel gun leaks badly enough to fill the inner barrel completely with water then the hydraulic lock will occur even as the piston departs the sear catch, but the piston cannot now get up to high velocity and so the very high hydrostatic pressure spike does not occur and a slow shot results instead. If the muzzle seal was absolutely perfect (we will just assume for the moment that the water got in some other way) then the hydrostatic pressure in the inner barrel would equal the air pressure in the gun and that would blow the spear tail out of the piston, the gun virtually becoming a hydropneumatic gun like an "RPS-3", except that as the spear departed the piston would be close behind it as the trapped water now had a way out, everything then being pushed along by the air pressure behind the piston.

So with a vacuum barrel gun you either have to keep water inside the inner barrel to a minimum (you need some water for lubrication of the piston and muzzle seals) or you have to provide it with another way out of the gun if too much "excess" water gets into the inner barrel beyond the muzzle "accommodation" volume.

 

[popgun pete]

This simple diagram shows how a shaft is pushed out through a muzzle seal by a hydraulic lock condition. Hydrostatic pressure operates in all directions inside the flooded muzzle under the influence of the moving piston, which is not shown here. The surrounding fluid pressure exerts forces which act radially inwards onto the shaft body and which all cancel each other out, but the force from the hydrostatic pressure acting on the spear tail is not matched by the pressure existing outside the pressurized vessel when looking inwards. That force imbalance causes the shaft to be pushed out of the muzzle while the hydrostatic pressure inside the muzzle is greater than the ambient pressure outside.

 

[tromic]

Thaks Pete for your detailed explanation! That is what I have been talking about...

 

[pigna79]

Hi guys,
I'm the owner of this video about one air. I think it's right to explain all the facts: the problem is due to the piston, but it's not the original Sporasub piston, it is a X-Runner from STC. I tested it on my Omer Airbalete and i though it was ok also for Sporasub, but IT'S NOT! So the problem is due to the replacement of the piston with another one that's not compatible with the One Air. Despite of this the assistance of Omer/sporasub changes immediately the piston of the airgun, with a fast and complete assistance. I'm really satisfied of this airgun, you can see in my other videos how it works, tahnk you,
Andrea

 

[Diving Gecko]

David, maybe you missed my explanation:
http://forums.deeperblue.com/pneuma...ns-sporasub-one-air-2012-a-20.html#post902457

Your experience, using two guns concurrently, is very valuable, especially because they both had to have about the same loading effort. 18 bar - 13 mm piston, and 25 bar - 11 mm piston. In both cases about 24 kgf, not taking friction. Even I had not think about loading effort differences before. I believe friction force might be at least 4 kgf, otherwise O-ring would not be "movable" on higher depth (more than 20 m). I do not know the design details, like dimension of O-ring seat, so this is just my estimation.

Regarding loading the gun with Evo-Air it is not irrelevant (as Sub Fireman said) whether to omit step "1." or not. You were doing it right way. I would do it same, including step "1.".

It is true the were some problems with first version of x-power. Ive read there were some problems with Evo-Air in beginning too. My fist Tomba also had some problems. The slider was made in stainless steel and was heavy. TombaF7 had higher friction during loading.

Hi Tomi,
Yes, I missed it the first time around.
OK, well if the physics say that they should be the same (not including friction), then that's interesting. In reality, the Evo-Air is a lot harder to load. If I had to take a guess, I'd say 15-20%, perhaps more, harder to load. So, in a way, with a different system, I could make it 15-20% more powerful and still load it. So, Evo-Air has drawbacks as well. Like most systems.
Also, I noticed that the hole in the elastomer for which the spear passes through was very generous. I don't know if this is good or bad? I'd say that it was at least 9mm. Which was kinda good as it was not centered and it would not have been cool to have it rub against the spear...;-(. But I don't know if one would want it as small as possible to have as little water as possible there or maybe it doesn't make a difference? I know the hole will likely become a bit smaller for a moment when the pistons slams into the elastomer and you don't want it to get in touch with the spear, but it seemed oversized?

Best,
David

 

[Diving Gecko]

Hi guys,
I'm the owner of this video about one air. I think it's right to explain all the facts: the problem is due to the piston, but it's not the original Sporasub piston, it is a X-Runner from STC. I tested it on my Omer Airbalete and i though it was ok also for Sporasub, but IT'S NOT! So the problem is due to the replacement of the piston with another one that's not compatible with the One Air. Despite of this the assistance of Omer/sporasub changes immediately the piston of the airgun, with a fast and complete assistance. I'm really satisfied of this airgun, you can see in my other videos how it works, tahnk you,
Andrea

Hi Andrea,
THANKS so much for elaborating on your video and the causes behind the malfunction. It was still unclear to us, which was why I was curious about why it had been posted.

I think it is fair to say that OmerSub can not be blamed for this malfunction and it is nice to learn this.
OmerSub has also been very helpful in their communications with me and it's good to hear you had good experiences with them as well.

Great to hear your gun is up and running again and that you are happy with it.

 

[bmwgsboy]

Hi guys,
I'm the owner of this video about one air. I think it's right to explain all the facts: the problem is due to the piston, but it's not the original Sporasub piston, it is a X-Runner from STC. I tested it on my Omer Airbalete and i though it was ok also for Sporasub, but IT'S NOT! So the problem is due to the replacement of the piston with another one that's not compatible with the One Air. Despite of this the assistance of Omer/sporasub changes immediately the piston of the airgun, with a fast and complete assistance. I'm really satisfied of this airgun, you can see in my other videos how it works, tahnk you,
Andrea

Thank you for your reply
I have been talking with Mark(sporasub US)
He has been very helpful in explaining the one air
He has had 5 guns returned for that reason.( stc piston)
Its best to follow the Manufacters instructions.
I don't understand why sub fireman decided
To show a video and just said it was no good
Instead of saying it was the piston. If sub fireman is looking for a my
Product is better than yours fight. He should be going after
Stc not sporasub. He knew all along the problem was
The piston why didn't he just say it??

 

[Diving Gecko]

This stuff is not exactly rocket science, but perhaps I can explain a little more...

THANKS Pete,
I got, finally got it all down in my head. I was close, but this made it happen.
The main issue has to do with whether the amount of water "trapped" is accommodated or whether there is excess water.
I keep thinking that Tomi is right in regards to the Evo-Air process as having the seal open on inserting the spear makes sure there is no excess water in the muzzle but only accommodated water. No matter what, I can't see that his loading process could harm at all.

Thanks,
David

 

[tromic]

Thank you for your reply
I have been talking with Mark(sporasub US)
He has been very helpful in explaining the one air
He has had 5 guns returned for that reason.( stc piston)
Its best to follow the Manufacters instructions.
I don't understand why sub fireman decided
To show a video and just said it was no good
Instead of saying it was the piston. If sub fireman is looking for a my
Product is better than yours fight. He should be going after
Stc not sporasub. He knew all along the problem was
The piston why didn't he just say it??

Interesting, but I was sure that such a slow motion shooting like that on video (it is now removed by the user) has nothing with the piston. It seemed like the barrel was full of water. If the piston had been broken loading of the gun would be very difficult (in case of crack in pistons body) or there would be no pressure in the gun at all. That is something that the user of the gun must notice.

 

[bmwgsboy]

Interesting, but I was sure that such a slow motion shooting like that on video (it is now removed by the user) has nothing with the piston. It seemed like the barrel was full of water. If the piston had been broken loading of the gun would be very difficult (in case of crack in pistons body) or there would be no pressure in the gun at all. That is something that the user of the gun must notice.

Good point
Maybe the piston broken when he shot it?!
Don't know I'm no expert.
But sub fireman did say he dident want to explain
Anymore and put up a fun video to watch.
I do know that they are having problems with the
Stc piston,5 that I know of including the owner of that
Video says it was the piston from stc, so one would think
That would be the problem.
All I'm concerned with is loading underwater
While on scuba.sporasub says its not a problem
We shall see.

 

[tromic]

I have not seen x-power for One Air, but it might be the safest kit to load under water. Maybe as safe as Evo-Air, but easier to use. My opinion is that these kits are safer for 11 mm barel than for 13 mm barrel. Still the safest method for any kit would be empting water before loding the gun. The only exception for free shaft will be, maybe (oncoming time will show), TombaF700HD (TombaF with hydro damper).

 

[Sub Fireman]

Interesting, but I was sure that such a slow motion shooting like that on video (it is now removed by the user) has nothing with the piston. It seemed like the barrel was full of water. If the piston had been broken loading of the gun would be very difficult (in case of crack in pistons body) or there would be no pressure in the gun at all. That is something that the user of the gun must notice.

Tomi response simultaneously with the registration of the person on this forum and its subsequent CANCELLATIONS Video occurred on at least two occasions in addition to the topic of the direct line to the company on the Italian forum is unequivocally declared the incompatibility 'of the piston not original to which attribusice full responsibility shall release of fact the product One Air.
I agree with what was said by Tromic in his speech.

 

[Diving Gecko]

Tomi response simultaneously with the registration of the person on this forum and its subsequent CANCELLATIONS Video occurred on at least two occasions in addition to the topic of the direct line to the company on the Italian forum is unequivocally declared the incompatibility 'of the piston not original to which attribusice full responsibility shall release of fact the product One Air.
I agree with what was said by Tromic in his speech.

I am not sure what this means.
Perhaps Tomi can help out with translating...? I know you can communicate in Italian as well.
Unfortunately, I am still not sure why Sub Fireman posted the video in the first place and followed up with 1-2 promo videos of his own product and then refrained to elaborate on why or what was wrong in the first video.
And now, we have the owner of the gun saying one thing (broken piston) and we have Sub Fireman saying something else (not sure what exactly) and Tomi feeling it is still a flooded barrel.
Might I propose that we let this rest for now? I think that is only fair.
For now, without fully understanding what Sub Fireman's arguments and reasons are, I keep thinking he (as the Head of Seatec's Tech department and Evo-Air designer) is not the right one to raise concerns over the One Air. And actually, he might not even be doing that(?).

David

 

[bmwgsboy]

I am not sure what this means.
Perhaps Tomi can help out with translating...? I know you can communicate in Italian as well.
Unfortunately, I am still not sure why Sub Fireman posted the video in the first place and followed up with 1-2 promo videos of his own product and then refrained to elaborate on why or what was wrong in the first video.
And now, we have the owner of the gun saying one thing (broken piston) and we have Sub Fireman saying something else (not sure what exactly) and Tomi feeling it is still a flooded barrel.
Might I propose that we let this rest for now? I think that is only fair.
For now, without fully understanding what Sub Fireman's arguments and reasons are, I keep thinking he (as the Head of Seatec's Tech department and Evo-Air designer) is not the right one to raise concerns over the
One Air. And actually, he might not even be doing that(?).

David

Good call David
Do you have anymore vids
On your one air??

 

[Diving Gecko]

Good call David
Do you have anymore vids
On your one air??

No, sorry - still only have the first and only one so far from an earlier post (I am done with my spearing for this trip).
And it only has two shots caught on cam because I forgot to turn on the cam so many times. But I could not once track the spear with my eyes. It just shoots very fast and quiet. And unless there were rocks behind or under the fish, the spear went straight through them all.

Best,
David

THAILAND SPEARING 2013_03 - YouTube

 

[popgun pete]

Pistons are usually matched to the shock absorber anvil so that the high energy impact spreads the load evenly over their opposing surfaces. If the piston does not fit perfectly into the anvil, the profile may be very slightly different with respect to the curvature on the periphery of the contact areas, then the more localized impact can cause cracking of the components. With metal pistons and anvils any slight unevenness in the contact area gets hammered into shape as the metal can be gradually deformed to provide a perfect match, you can see this on older guns where the piston and anvil have created a perfect fit with each other after numerous shots through the gun. That will not happen with plastic pistons, or shock absorbers, they don't have any ductility, so mixing of components from other manufacturers needs the fit to be checked out before doing any swaps.

The elastomeric sleeve absorbs the energy, but the energy is transmitted by the piston contact with the anvil, so pistons and anvils should ideally be swapped in pairs. As the shock absorber has to fit the muzzle as well, this is not always possible, so mismatched parts may be placed into service which is not a very good idea. The reason that anvils have a hard face is to stop them being damaged by high energy piston contact that might tear up the face, the elastomeric sleeve being pushed in turn by a completely flat surface on the peripheral flange of the anvil body.

Just looking at the STC "X-Power" system again on their web-site, which is what is said to be used in the "One Air", I note that the shock absorber body has a rear face that appears to be made of some sort of urethane that should be more forgiving of the piston shape that slams into it. It does not appear to be a hard material like Delrin or Acetal. Does the Sporasub "One Air" have this same shock absorber body, or is it a variation of their own? I cannot find an STC piston on their web-site (now I have, it is on the "X-Runner" page, along with the shock absorber photos), but in what way does one differ from the standard piston used in the "One Air"? The STC "X-Power" system uses a captive special sealing washer, whereas the Seatec "Evo-Air" uses an "O" ring squeezed back in a tapered seat to radially compress it by a certain amount for loading. My guess is if you squeeze the "O" ring by just the right amount then the loading effort will be less and it will still seal OK, but if you cram it right down on the back of the tapered seat then the friction goes up and creates too much effort in muzzle loading. A thin washer behind the muzzle nose-piece may help in limiting how far back you push the "O" ring in the tapered seat when you tighten the "Evo-Air" muzzle nose-piece up, or you just don't twist it as much. Maybe put a mark on it to find the right amount of tightening so that the mark lines up with another one on the muzzle body at the best position for muzzle loading.

 

[Diving Gecko]

A thin washer behind the muzzle nose-piece may help in limiting how far back you push the "O" ring in the tapered seat when you tighten the "Evo-Air" muzzle nose-piece up, or you just don't twist it as much. Maybe put a mark on it to find the right amount of tightening so that the mark lines up with another one on the muzzle body at the best position for muzzle loading.

Very good ideas indeed!
Since the Evo-Air design with the same size o-ring(?) has to accommodate spears from 6.5-7mm it makes sense that the bigger sizes will be held quite tight if the muzzle is tightened all the way down. I suspect, the fully tightened position would be needed for 6.5mm spears and with bigger spears, it just adds extra friction and not extra needed sealing.
I put a question mark after the "o-ring" as the kit does come with 2 extra o-rings but I am pretty sure, they are just replacements in the same size. The manual doesn't say anything else.
Seatec could actually have implemented one of three possible improvements:
1). Ship with three different sizes of o-rings, so that one could always just tighten all the way down and not have to worry about over-tightening (problems with marking o-rings to avoid using the wrong one)
2). Ship with different spacers (easy and clever)
3). Mark the muzzle (perhaps the cleanest option from a design standpoint)

On my next trip, when I take out the gun again, I may just try to bring different sized spacers and experiment a bit. Would be nice if it was easier to load.

 

[tromic]

Pistons are usually matched to the shock absorber anvil so that the high energy impact spreads the load evenly over their opposing surfaces. If the piston does not fit perfectly into the anvil, the profile may be very slightly different with respect to the curvature on the periphery of the contact areas, then the more localized impact can cause cracking of the components. With metal pistons and anvils any slight unevenness in the contact area gets hammered into shape as the metal can be gradually deformed to provide a perfect match, you can see this on older guns where the piston and anvil have created a perfect fit with each other after numerous shots through the gun. That will not happen with plastic pistons, or shock absorbers, they don't have any ductility, so mixing of components from other manufacturers needs the fit to be checked out before doing any swaps.

The elastomeric sleeve absorbs the energy, but the energy is transmitted by the piston contact with the anvil, so pistons and anvils should ideally be swapped in pairs. As the shock absorber has to fit the muzzle as well, this is not always possible, so mismatched parts may be placed into service which is not a very good idea. The reason that anvils have a hard face is to stop them being damaged by high energy piston contact that might tear up the face, the elastomeric sleeve being pushed in turn by a completely flat surface on the peripheral flange of the anvil body.

Just looking at the STC "X-Power" system again on their web-site, which is what is said to be used in the "One Air", I note that the shock absorber body has a rear face that appears to be made of some sort of urethane that should be more forgiving of the piston shape that slams into it. It does not appear to be a hard material like Delrin or Acetal. Does the Sporasub "One Air" have this same shock absorber body, or is it a variation of their own? I cannot find an STC piston on their web-site (now I have, it is on the "X-Runner" page, along with the shock absorber photos), but in what way does one differ from the standard piston used in the "One Air"? The STC "X-Power" system uses a captive special sealing washer, whereas the Seatec "Evo-Air" uses an "O" ring squeezed back in a tapered seat to radially compress it by a certain amount for loading. My guess is if you squeeze the "O" ring by just the right amount then the loading effort will be less and it will still seal OK, but if you cram it right down on the back of the tapered seat then the friction goes up and creates too much effort in muzzle loading. A thin washer behind the muzzle nose-piece may help in limiting how far back you push the "O" ring in the tapered seat when you tighten the "Evo-Air" muzzle nose-piece up, or you just don't twist it as much. Maybe put a mark on it to find the right amount of tightening so that the mark lines up with another one on the muzzle body at the best position for muzzle loading.

Pete, where did you find this information, that there is a tapered seat for the O-ring? I missed that information. Some time ago, in a post I supposed there was a taper for O-ring in Evo-Air, but actually I do not know if it is ture. The early version of Evo-Air had not tapered seat. But if the new version has it, your proposal might be a solution for easier loading. The problem will be to determin the optimal depth for O-ring for 6.75 and 7 mm shaft. This is not an easy task as it seems. You can not rely on "feeling". Only reliable way is applying measurement and O-ring calculation.