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Infinitengines "Dreamair" pneumatic speargun
- Thread starterpopgun pete
- Start date
Thread Status: Hello
, There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
It can take a long time to get an up-to-date response or contact with relevant users.
On the Greek spearfishing web-site I found these interesting views of inside the barrel of a multi-axle gun as can be seen by the two sets of sub-pulleys being used. This would be a four axle gun as there are four cable strands running towards the muzzle, one cable per inner winding drum on each axle.
Finally got around to correcting this diagram as previously it was confusing as I had swapped the gearing indicators inadvertently. Start gearing may be 1.1:1 or 1.2:1 rather than direct, however you can judge for yourself using the winding drum axle assembly photo which follows.
Answer is given in post #241, the piston being pulled slightly forwards halts the spinning axle.
interesting gun, but i see one bad moment, when the cord inside of tube is going to broke the hunting day will be finish )
and then another moment comes out, how many times of changing cord the parts of gun will stand, an till it broke ? 50 ? 100 ? 200 ?
i doubt about aluminum and plastic parts will last longer then 50 times of disassembly and assembly
and then another moment comes out, how many times of changing cord the parts of gun will stand, an till it broke ? 50 ? 100 ? 200 ?
i doubt about aluminum and plastic parts will last longer then 50 times of disassembly and assembly
Thousands of test shots have been put through the guns and none of the above supposed events happened, the real question is will we ever see them as repeated queries to the inventor on this matter have drawn no response in the last few months. It is possible that financial problems have been created by a protracted development time with no gun sales to bring in any revenue. It was a mistake not to sell the alloy guns first, then do the carbon guns. Again if say a supplier wanted a firm order for specialist alloy tubing and the money was (or is) not there to pay for it at the time then this could have created an insurmountable problem with the alloy gun. I have been involved with many projects in my career and funding can be a stumbling block, unless the risk is taken to float the company and secure more financial backers.
yep ! definitely is a wrong way passing to carbon for pneumatic gun .. totally wrong for technical reason first and only then financial
it gotta be very high priced gun even with alloy barrel
It is just purely supposition on my part, but if there was no way forward on material supply for an alloy gun due to financial or supply problems then a carbon body gun would enable this to be totally circumvented. I know some carbon guns were built and they worked OK, but their barrels would require more steps in making them, whereas metal tubular extrusions are just cut off to the required length from a long piece of stock tube. For example a length of tubing may be enough for three alloy guns, but carbon fiber barrels would need to be laid up on mandrels to create each one. Basically one dependency is swapped for another with the danger that the market loses interest and perhaps patience. These guns were initially flagged for release in 2014/2015.
Even if the guns were say USD 800 to 1000 then I would expect that 200 or maybe 300 guns would have been sold by now as collectors would snap up the first 100 or so, followed by early adopters. There are tens of thousands of spearfishermen around the globe, so only a fraction need to buy these guns.
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I respectfully disagree with the "totally wrong" part as it almost sounds like it would/could never work;-).
Pete and I actually had this talk in private when he first learned of the change to carbon and though I couldn't come up with real world examples of carbon tubes being used with sliding pistons there are many carbon fiber parts are being made in molds these days with the top coat being sprayed into the mold first - not as final step after the part has been pulled from the mold.
This is what leads me to believe that it can be done on a mandrel, too for a speargun.
I don't know how it's being done on the Dreamair but just speculating that perhaps this is how they do it.
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that reminds me several same cases, when the skilled inventor of speargun started PR company on the web, and even produce and sale some guns,
but finally all stop, mostly on first prototype
very difficult to make production of complicated speargun with reasonable profit $ AND with stable quality, AND win a competitions with mass produced spear guns
and then gun is more complicated, than those 3 factors play harder
ps
i guess even with alloy barrel this roller gun will cost not less than 1,5k$ ! and with carbon not less than 3k$ !
and this gun doesn't have any type of shooting power reduce option on the action in water, like usual multi band speargun or roller gun or pneumatic gun can offer
which make this Dreamair gun not universal to blue water&reef type of hunting
is a few technical factors play against idea to use carbon like air tank and as cylinder for piston, yeah u can do it and it will work
but .... i see at least 4 factors against that way
1 air pressure will loose through carbon tube with time
2 significantly more friction in tube for piston and seals
3 significantly less strong barell for any damage
4 significantly high price in compare with alloy
in industry only metal used as cylinder for piston, or metal+ceramic as exotic )
I do agree with the difficulties an endeavor like this most likely run into. Just today I had a chat with a spearo friend about how many of the big name brands in Europe are possibly worse in quality now than before and yet people gladly buy them because of brand name and affordability. And I'm also beginning to think that 800 bucks might be naive of us to hope for. I think that number came up many posts back when we tried to figure out what people would pay for it.
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I have four or more guns with carbon fiber reservoirs by now. If they loose air it is so negligible I personally wouldn't mind.
Whether a carbon tank would loose air would mostly likely depend on the quality and thickness of the layup. Perhaps the resin content, too. I know "carbon scuba tanks" actually have an inner alu liner but isn't that to have a shape to actually lay the fiber onto? I'm fairly sure there are pressurized carbon tanks being done around the world without liners. I googled it a few years back and did get some examples though can't really recall what they were.
Friction? You can get some incredibly strong, mirror finish top coats now - of course the mandrel has to be perfect, too. And "duralumin" or whatever the alloy is that is regularly used for our oleo barrels isn't really that smooth. I have polished some of mine and made them a whole lot smoother but from the factory or anodizing tank they are honestly not super impressive. Also, a lot of people claim big efficiency gains by swapping to stainless barrels though I wish someone would properly test this.
As for strength, the Dreamair won't run very high pressures - less than 10 bar if I recall correctly. I have had some of my regular 40.5mm cylindrical reservoirs up to 35 bar by now (1.25mm wall thickness and no-name chinese fabric and resin) and dropped them a few times while pressurized, too. They have been fine. Can't talk about long term issues as I only spear a month or so a year and the oldest one is just a few years old by now.
I probably agree with point 4;-). Thing is, an extrusion factory might have quoted a very high price to make the tooling and start production so for smaller runs, it might not have been viable. Dreamair is not really in the habit of sharing much info so we are all mostly guessing here...
As for what is industry standard probably has more to do with point 4 than anything else. I'd also speculate that uses where "exotic" ceramic materials come into play might sometimes be in high temp environments? Not really what epoxy does well.
Overall, I agree that alu would have been the safer/better choice for a first gun - I just happen to believe that technically, you can do it in carbon fiber.
Pete did a poll at one point about which option people would prefer. I didn't actually vote, haha. I love carbon but I would like Dreamair to actually make guns soon instead of me dreaming about which material it should be in. Or at the very least tell potential buyers (us) more about the holdups and challenges. Especially in this Internet age. But I have elaborated quite a bit on that earlier on in this thread.
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am really curious why anybody need four or even more, uncountable quantity of guns with carbon fiber reservoirs.
and what exactly models of carbon fiber reservoirs pneumatic speargun do u have and for what type of spearfishing u use it ?
what the benefit of carbon fiber reservoir on pneumatic speargun except is WOWthing?
Carbon fiber has become the material to use for stiffer band guns which are strong and relatively light as they have a central void or can be built on a foam core, however as pneumatic guns are coaxial spear shooters they don't have to resist bending from off-axis loading. Pneumatic guns need some mass for the usual conservation of momentum requirements as gun and diver need to be more massive than the projectile. The “Dreamair” is an exception as it is a pressurized vessel which is subjected to internal tank pressure and off-axial loading from the cable draw on the top deck. If I was manufacturing the “Dreamair” then I would produce an alloy tube gun by selecting an extrusion similar to the tank tube of the elliptic Omer “Cayman” as it has a smooth bore tube and a spear guide track on top. That can withstand off-axis loading in the band gun. Although it has no guide track the alloy tube of the Sporasub “One Air” also has a triple chamber tank that would do the job, plus it has a central cylindrical bore. Both these extruded alloy tubes would be available in commercial quantities.
For a carbon fiber gun I would use an alloy liner for the sliding bore and build the gun up on that thin wall tube as a fixed mandrel, in which case I could then have a composite tank wall as the tank wall would be carbon fiber with an inner sliding surface “core”. It is possible that the carbon fiber gun may be slighter lighter than the alloy gun and not susceptible to tank dents. If standard pneumatic tanks are dented, which is a thing to avoid, it makes no difference to gun performance, however if a tank was dented on an oval piston “Dreamair” then it would cause a problem for the big oval sliding piston sliding past the dent by creating a tight spot, a problem which would not occur with a three chamber carbon fiber gun as the inner bore would be completely isolated from external knocks.
The Omer tube is a difficult bore shape, however the matching piston would not rotate in the bore and thus avoid the inner cable twisting. Connecting rods on either side would hold the gun together, their screw threaded ends can be seen on the "Dreamair" photos.
For a carbon fiber gun I would use an alloy liner for the sliding bore and build the gun up on that thin wall tube as a fixed mandrel, in which case I could then have a composite tank wall as the tank wall would be carbon fiber with an inner sliding surface “core”. It is possible that the carbon fiber gun may be slighter lighter than the alloy gun and not susceptible to tank dents. If standard pneumatic tanks are dented, which is a thing to avoid, it makes no difference to gun performance, however if a tank was dented on an oval piston “Dreamair” then it would cause a problem for the big oval sliding piston sliding past the dent by creating a tight spot, a problem which would not occur with a three chamber carbon fiber gun as the inner bore would be completely isolated from external knocks.
The Omer tube is a difficult bore shape, however the matching piston would not rotate in the bore and thus avoid the inner cable twisting. Connecting rods on either side would hold the gun together, their screw threaded ends can be seen on the "Dreamair" photos.
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As a sign of maybe things nearing completion I now have a LM002 in black, and much larger than the silver one. Now I just need two "Dreamair" guns to lean against it for that photo.(post #128)
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It's a combination of just wanting to try it, some wow (I like the look) and because I really want my guns light in the water and though you don't save much weight, it all counts. Why four? Because I have customized around four guns by now. So, probably not much if any benefit other than the personal satisfaction of having done it. People like different things, I hope that's alright with you.
The number of guns was not to say I have lots of guns (I don't and it wouldn't matter anyways) - It was to tell you that I have not noticed air loss through the laminate in any of them. Whether it wouldn't happen over the course of, say, a year or so, I don't know. My feeling is that it wouldn't.
You can search my profile to see examples of some of the guns. It's just modified traditional guns. One short Sten, one Seac Hunter and a few Mirages by now
While I, personally, think Andreas (Dreamair) could have done a much better job at communicating through the years I applaud the energy and skill he is putting into the project. And while the gun may not suit me and while I still want to see that there really is a power advantage I try not to criticize things about the gun that I'm not very sure about.
E.g. I don't think one can categorically say a carbon reservoir will loose air. And honestly it's potentially a quite damaging thing to say about the design.
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