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Infinitengines "Dreamair" pneumatic speargun

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.
Happy New Year! I wish you an experiment with a gun from the refrigerator! Based on the results of this Experience, it will be possible to conduct further discussion, possibly in a separate Topic! Health and good luck to all!
Another advantage of the "Dreamair" is the gun is unaffected by ambient pressure as the compressed air and sliding piston system is totally enclosed. It will have more frictional losses than a standard pneumatic speargun, but has the big advantage of loading from the rear. Many spearfisherman who are more used to bandguns don’t like muzzle loading, especially with one hand, but this is often because they have never tried it.

At 800 euro the gun is not that expensive, I paid much more for my carbon fibre Seal 130 inverted roller cable gun. However I look forward to the aluminium version if and when it is in production.
Some recent photos showing gun accessories and the mounting position for a reel.
accessories for dreamair.jpg

reel mount position.jpg

cocking position.jpg

cocking procedure.jpg
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Extra photos are appearing each time a gun goes to a customer, 2 guns appear to have gone out recently, one in late December and one at the end of January. Both are Dreamair Unreal 100 cm models with the single aluminium barrel embedded in the carbon fibre body. That barrel is for the piston to slide back and forth in
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Another gun delivered yesterday and with it a photo showing the pumping table for this 100 cm model.
pump table for alloy tube model.jpg

Note the long body tube for the hand pump.


  • pump table for alloy tube model.jpg
    pump table for alloy tube model.jpg
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The basic advantage of this speargun design is that it combines the much more efficient energy storage of a pneumatic system with the ability to load the gun with both hands. On a normal pneumatic gun you need one hand to stabilize the muzzle while you pull on the loading handle and if needed can only employ the other hand once the spear is nearly fully inserted and the gun is no longer in danger of pivoting off your foot where the rear handle is pressing.

The big diameter piston of 500 mm squared cross-section means that internal start pressure can be relatively low while providing a high level of force for spear propulsion. As water never gets inside the gun the piston has pressure on one side and a near vacuum on the other in what is a sealed system, so it is completely unaffected by ambient pressure at depth.

Rather than the piston pushing the spear it pulls it via a cable drive using an axle in the muzzle. The only other pneumatic guns with rearward travelling pistons as they shoot are the hydropneumatic guns, but facing water braking inside the gun they require very high start pressures or multiple loading strokes to drive shooting pressure up. This makes for a lowered operating efficiency compared with standard pneumatic guns, while the Dreamair's high efficiency will only be offset by friction of the piston seals and the need to wrap and unwrap the cables and spin the pulley/drum axle. A big loading effort can be used as the spear is no longer transmitting the force to the piston during loading as like band guns loading and gun cocking are two separate tasks.

Pneumatic guns combine loading and cocking which is very efficient while the gun body and spear are short, but drops away if cocking requires several pushes to complete the charging of the gun for shooting when the gun is much longer.
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To obtain a piston cross-sectional area of 500 square mm the diameter of the piston has to be slightly over 25 mm, therefore it is about double the size used in most pneumatic guns of a conventional layout. An even larger piston of double the area was used in the oval bore alloy guns which were essentially monotubes.
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A three barrel carbon fibre 100 cm gun has been delivered, which is the top specification model.
3 barrel carbon fibre 100 cm.jpg
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Did you get one, Pete?

If so, tell us how it goes please.
No, I am waiting for the alloy gun, I don't need another carbon fiber gun. However if that gun never eventuates except for those early alloy prototypes then I will need to reconsider. Carbon fiber is not my preferred material for an air tank.
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