Infinitengines "Dreamair" pneumatic speargun

[popgun pete]

I have also discussed this gun in the "band gun world" here http://www.spearboard.com/showthread.php?t=191119&highlight=Dreamair and here http://spearfishing.world/spearguns...atic-invention-traction-roller-dyneema-4.html

The main advantage is no muzzle loading as you cock and load the "Dreamair" from the rear end.

"I would like to see the gun succeed, but it faces a number of problems, including potential inefficiency. Rather than the power angle I think the greatest benefit is that risky muzzle loading is eliminated, but I say that as a spearo who has fired and loaded all manner of pneumatic spearguns for many decades. However on occasion there have been some near misses (personally) and a few unlucky individuals have received a spear in the head when carrying out this task, often being complicit with their own stupidity, e.g. using a tin can as a hand loader."

 

[Diving Gecko]

Steady performanse regardless of the time under tension;
no aging of rubber bands; no need for bands at all;
there is no friction of bands in water...

Tomi, why on earth should we compare it to a rubber gun... haha;-)
Joke aside, I do get your points, and perhaps this is what the inventor thinks, too - it looks like a bandgun and loads like one, so perhaps that's who he is targeting.
But when compared to oleos, if you can't store more energy in this gun than in, say, a vacuum muzzled traditional gun, then I don't know how it can be more powerful?

 

[Diving Gecko]

I have also discussed this gun in the "band gun world" here http://www.spearboard.com/showthread.php?t=191119&highlight=Dreamair and here http://spearfishing.world/spearguns...atic-invention-traction-roller-dyneema-4.html

The main advantage is no muzzle loading as you cock and load the "Dreamair" from the rear end.

"I would like to see the gun succeed, but it faces a number of problems, including potential inefficiency. Rather than the power angle I think the greatest benefit is that risky muzzle loading is eliminated, but I say that as a spearo who has fired and loaded all manner of pneumatic spearguns for many decades. However on occasion there have been some near misses (personally) and a few unlucky individuals have received a spear in the head when carrying out this task, often being complicit with their own stupidity, e.g. using a tin can as a hand loader."

Got you... but if that advantage comes with a drop in outright power, then for me, it is not worth it. Also, it is quite a complex gun. Especially, the inner drums have to spool up nicely and never ever kink - otherwise, it is a full tear-apart and pumping it back up to get it back to work.

I guess, it comes down to how much energy one can actually store in this gun. Can we load it with more energy than a traditional pneumatic gun or a rubber gun, then it might have a chance. If not, then it is still a very beautiful but over engineered solution to a problem that is not really that big...;-)

Once I have a proper Gecko Mirage up and running, that should be more powerful as that gun offers a way to store more energy than a traditional oleo but so does a multi-band rubber gun for that sake. (THANKS for the PM poem, btw!)

 

[popgun pete]

Remember that you can use both hands working together on the wishbone to load it, whereas with a loading bar you can usually only use one hand, unless you have a double-handed loader and can put the gun butt on something else.

 

[Diving Gecko]

Remember that you can use both hands working together on the wishbone to load it, whereas with a loading bar you can usually only use one hand, unless you have a double-handed loader and can put the gun butt on something else.

With 'loading bar', you mean a hand loader for pneumatics? I sometimes need two hands on it at the end of the loading effort, just before latching. By then, the spear is deep in the shooting barrel and thus well supported anyways there's no risk of it bending.

 

[tromic]

Tomi, why on earth should we compare it to a rubber gun... haha;-)
Joke aside, I do get your points, and perhaps this is what the inventor thinks, too - it looks like a bandgun and loads like one, so perhaps that's who he is targeting.
But when compared to oleos, if you can't store more energy in this gun than in, say, a vacuum muzzled traditional gun, then I don't know how it can be more powerful?

I agree. It can not store more energy neither be more efficient regarding energy than your Mirage. It has more energy losses on additional parts not present in regular pneumo-vacuum spear gun.

 

[popgun pete]

With 'loading bar', you mean a hand loader for pneumatics? I sometimes need two hands on it at the end of the loading effort, just before latching. By then, the spear is deep in the shooting barrel and thus well supported anyways there's no risk of it bending.

A "loading bar" is the old term for the hand loader as spring guns used a "loading bar" and so did the early pneumatic guns by engaging a transverse hole located just behind the spear tip, or the threaded end tip on the shaft. Another term is "charging pin", as they all do the same job. Where you really need two hands is when you cannot budge the shaft and the loading length is still at SLL MAX!

 

[Diving Gecko]

Thanks for clarifying. I disagree a tiny bit, though;-). At SSL Max the spear is just dangling around and if you put both hands on the loader, and none on the muzzle you will def risk the shaft bending, right?
Except if it is such a long gun that you use an extended loader - which leads back to my earlier argument that they actually offer more support to the shaft (as you 'hold' it halfway down) and often makes loading long guns easier than a shorter ones at very high pressures.
Anyways, that is for another thread.

 

[tromic]

Easy Loader is the most appropriate loader for such tasks
https://forums.deeperblue.com/thr eads/air-gun-easy-loader.74889/page-4#post-881754

 

[popgun pete]

SSL MAX is when the spear tail is jammed into the face of the piston, the tail will not fall out, in fact you generally have to yank it free or stand on the opened-out floppers and pull the gun upwards to free the shaft from the piston. Metal pistons have a really tight grip, plastic ones offering less resistance, so they can usually be jerked free with a rapid movement provided you have a good grip on the shaft via the floppers, or use a perforated wooden block to catch behind them. The unsupported nature of the shaft at SSL MAX is what makes the use of a double-handed loader risky as nothing is stopping the muzzle moving around unless you push the shaft in axially and right on the centreline of the gun's support base. I loaded my Seabear MAK 103 that way as there was no other way that it could be loaded otherwise with over 400 pump strokes put into it! Anyway let us not make this a debate over extended loaders, here we are talking about the "Dreamair". Loaders have their own thread here: https://forums.deeperblue.com/threads/hand-loaders.106972/

 

[popgun pete]

I decided to draw the "cocked to shoot" and "discharged" conditions in separate diagrams as everything then becomes much clearer compared to having them both combined in a single diagram.

 

[tromic]

Yes, now it is much more clearer!

 

[popgun pete]

The "Dreamair" claims a victim!

 

[foxfish]

What is it? is there more of a story?

 

[popgun pete]

What is it? is there more of a story?

The successful hunt is featured on the web-site https://www.facebook.com/infinitengines/?fref=ts
as "First spearfishing with Dreamair by Trifon Bargaui. First blood. Congratulation!!".

I would expect that it has all been written up on a Greek spearfishing forum, but I have not yet looked for it.

 

[tromic]

Now when I look at the image of the gun I wonder what keeps the outer cable from being unwrapped from the outer drum? Is it some kind of spring cable?

 

[popgun pete]

That is a good question, just looking at it now the cable does not appear to be held in place by anything, but I don't think the cable itself is springy as such. If you look at the original sketches of the muzzle there appear to be shroud covers with a slot in them to pass the cable through. Maybe they will be fitted later.

 

[tromic]

To me it looks like the cable is held in grooves just by friction. It does not seems to be springy. Maybe the groove width is same as the OD of the cable? The deepness of the groove might be similar to its width. But in that case there is a possibility to be occasionally unwrapped at least on one side, maybe for just a few turns that should be wind back before loading the gun.

 

[popgun pete]

If you look back at the Operating Cycle diagram then you will see that the first wishbone draw moves the piston by 1/4 of the tank length and the second wishbone draw by another 1/4 which moves the piston to the half-way mark. Halving the volume will mean a doubling of the pressure, thus the compression ratio is 2.0. At the first wishbone draw the tank volume will be 3/4 of the original length and therefore the compression ratio will be 1.33. For a start pressure of 10 atm the end pressures will be 13.3 atm (after one wishbone draw) and 20 atm (after the second wishbone draw). Thus the "Dreamair" gun has two shooting powers depending on whether one wishbone or two wishbones are cocked. This "dual power" facility only applies to the twin axle version as cocking of that gun is staged, whereas the single axle version loads in one pull.

 

[popgun pete]

The high power/low power diagram for the "Dreamair" twin axle speargun.