Infinitengines "Dreamair" pneumatic speargun

[Diving Gecko]

So, going back over some roller gun research I once again read Chris Coates' roller gun tests from a few years ago. Looking at vids of Chris, he looks pretty buff and with decades of experience in the water, I think he has his loading technique sorted, too.
Chris mentions he has set up the rollers with max 60kg at the last sharkfin/notch. He says: "... the 60kg is fairly hard to load and not everyone will be able to load a gun like this. (Approximately the same as loading a conventional 130cm gun with a very short 20mm rubber)".
BUT as for pretensioning, which decides the force needed to pull the bridle off of the muzzle he stays between 15-20kg without a load assist and seems the max he goes up to with a load assist is 32kg.
Personally, I still don't really think I can pull 60kg at the rear and certainly not double that at the muzzle. Part of me think Andreas overdid it on the theoretical power a standard spearo can put into the gun and when he realized, he came up with the loaders and especially the pulley loader. We have had the 120kg/60kg force diagram pretty much since day one, but as far as I can judge from the timeline, it took a while before the pulley loader appeared.
Anyhow, I think we are in for a bit of a wait before Pete gets his hands on an alu barreled gun as it was all put on hold when Andreas started working on CF gun. His latest statement was that now that the CF gun was sorted it was time to get back to the alu one.

 

[Diving Gecko]

Earlier on in this thread it was claimed that carbon tubes slowly leak when used as pressurized containers. With anecdotal experience of my own, I stated that my Chinese tubes had not leaked as far as I could tell. Now, I thought, I'd share an update. The last time I used my long Mirage with a very cheap Chinese tube was in March of last year and then I stored it with friends. Just today, 9 months later, I took a reading and the gun still sits at the 28 bar I left it at. So, yeah, I think it is safe to say, that they hold air.

 

[popgun pete]

It was not so much that carbon fiber tubes would leak, it was that they may crack which could lead to leaks. Alloy tanks are unlikely to crack unless they have been flexed at a dent which has subsequently been straightened out which would fatigue the alloy through rapid work hardening. It really depends on the knocks that the tank endures and how thick the tank wall is. One advantage that pneumatic guns have is that they are not too heavy and impacts if dropped are much less than say with a scuba tank which is a relatively heavy object. Pneumatic guns don’t often have things dropped on them, but judging by the dents in some guns it happens. The old sinking guns had quite thick tanks as in their time pneumatic guns were not thought of as ever being floaters. That awaited the introduction of plastic parts and buoyancy chambers in gun handles.

 

[Diving Gecko]

The comments I referred to were not yours but they definitely were about leaking. And I just wanted to put that rumor in the ground.

 

[popgun pete]

A new photo of the "Dreamair Unreal" has just been added to the site. It appears to not have the outer drums fitted as you can see the ends of the axle.

 

[Diving Gecko]

All he did was swap his banner image on Facebook. No words, no updates, still no resurrection of his website. Will be nice once the Unreal actually becomes real.

 

[popgun pete]

Well any change was better than nothing, at least it shows things are still going. I check each day and when I first saw the changed banner I thought that there would be more, however we will just have to wait and see. Scaling up for production requires some idea of the volume and the likely sales that will be generated as that sets the parameters for the production facilities and how much of the gun can be farmed out to sub-contractors.

 

[Diving Gecko]

A new video dropped today - carbon gun again.
(And... it's funny how people who like heavy metal rarely seem to understand that not everyone does).



Running 20bar, so he must surely have gone to a much smaller inner barrel.
Oh, I guess we already talked about that but with the low frequency of news on this gun, I find myself constantly forgetting about it.

Is it me or does it look like the wishbone winds onto the underside of the drum?

 

[popgun pete]

I just watched it and the drive cable, which here looks a blue shade, does seem to wind on from the bottom of the drum. The shooting line is yellow and now the gun has its name on it in white lettering. After the shot you can see the wishbone flopping from side to side under the nose of the gun, which makes me wonder if the cable has fully wound on the drums.

This patent drawing shows the drive cable winding from on top of the drum.

 

[popgun pete]

Well I inquired and apparently some earlier shots were with the drum winding from underneath, including the alloy barrel gun, but it was not easily seen in the videos. I certainly never noticed it. My assumption is that if the cable pulls from on top of the drum then it keeps the cable off the gun body and eliminates wear and friction there, even if it was minimal with the lubricating effects of water.

 

[popgun pete]

Still dreaming!

 

[Diving Gecko]

Yeah, I noticed that flapping wishbone, too. Even it is fully wound on and the cable is a tad too long perhaps it flapping around like that increases the risk of it coming off the drum.

The shot itself looked quite powerful.


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[Diving Gecko]

Oh, he actually did name the gun 'Dreamair Unreal' for real... Brave man. Now, it certainly can not become vaporware as that would just be... hmm... harsh karmic justice/punishment...?

Well, here's back to cheering for him and all the hard, continued work.

 

[popgun pete]

This is how it was originally set up. The drums have to rotate in the opposite directions if they pull from on top.

 

[popgun pete]

The gun and its victim.

 

[ECK]

When I look at the drawings of this gun, my hair starts to move on my head. But on the gun, the drums look quite compact. Using a pneumatic motor offers many advantages over rubber. I am for pneumatics! Perhaps Andreas made the tackle difficult?

 

[Diving Gecko]

To me the question I am looking to have answered is if there’s any real world advantage over a well designed, efficient pneumatic gun...?
Does he have any issues or power losses we don’t know about or will it outshoot a normal pneumatic?
There are a few advantages to his design but so far they are mostly theoretical.


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[ECK]

Air rifle cannot use long thin shaft

Shaft airgun must have Line RETAINER SLAIDER

 

[popgun pete]

The big piston should be a source of drag, the inertia of the drums and spinning them up to velocity is something you don't have in other guns, but then it can have a large engine with more air pumped into it to store a lot of energy. Bar any leaks that engine should have a constant output, something that rubber is not very good at. What makes rubber useful is the low number of shots put through it which gives the rubber a chance to recover.

A key aspect is consistent cable winding on the drums, that has to repeat flawlessly for the gun to shoot straight.

 

[ECK]

Charging the "Dreamair Unreal" looks very uncomfortable for a long time. This is very similar to how he charged his Mirage Diving Gecko Can he tell how good it is?