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Infinitengines "Dreamair" pneumatic speargun

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popgun pete

popgun pete

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Infinitengines "Dreamair" pneumatically powered, cable transmission/roller drive system speargun.

http://infinitengines.com/

A proposed pneumatic speargun of a very different layout, but maybe it works better on paper than it will in the real world where cables have mass and momentum and can deviate from where they are supposed to go in milliseconds. An imaginative idea even so, but not very practical as complexity always brings with it added potential for failure where only one part not functioning can bring down all rest.
 
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tromic

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This is not a new idea: roller-pneumatic. Design is very nice, but I am not quite sure how might it work to be reliable. I suppose the working stroke of the piston is 1/2 of barrel length. CVT might have average ratio of 1 : 3 so it can accelerate the spear on useful length of the spear gun. CVT part of guns design might be the most interesting, but the shaft holding the piston is for me the most puzzling. Is it stiff or flexible like a cable? If it is a cable how it is sealed in barrel? Maybe it is a cable wrapped in plastic? That might facilitate a sealing problem.
 
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foxfish

foxfish

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Lovely pictures!
I am still waiting for a model that has a small diameter barrel mounted above the air chamber....
 
popgun pete

popgun pete

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Inventor: Andreas Zournatzis, Patent Number: WO2014001825 A1 (note "2014001825" is the actual number, a Google search will find it). The patent explains how it is intended to work, but there are a number of areas that will be difficult to engineer and function reliably. Inefficiency will be a problem, plus how things "operate" on paper does not always translate to reality.
 
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popgun pete

popgun pete

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A page from the patent depicting the two axle version, with my added comments, plus a diagram of the inner cable layouts for multi-axle versions as I interpret them. The patent is rather lengthy and repetitive to read on the different axle versions, but I think this is a correct interpretation.
Air powered cable gun 2R
Inner cable system RG
 
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tromic

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I suppose the high pressure in a barrel (maybe up to 30 bar) must be on side between rollers and the piston. It would be much easier if it could be on oposite side, but it is imposible with configuration as on upper images.
 
popgun pete

popgun pete

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When the gun shoots the piston moves rearwards pulling the drive cable backwards and thus spinning the axles which wind in the cable wishbones on the outer drums or spindles/pulleys. The inventor claims that the multi-axle versions multiply the energy storage of the gun, but they do not as the travel distance of the piston and the pressure in the gun determine that total energy storage value, just as they do on any pneumatic speargun. For the same gun length and piston travel the guns store the same amount of energy regardless of the number of axles used in the drive system, but there will be more energy losses with the more complicated versions as there are more parts to move and spin up to velocity.
 
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tromic

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I also see an another problem. If the gun would have the max force of 120 kgf than the actual force on piston must be maybe 3 x ... about 360 kgf. What kind of cable might be that if it also should be wind around rollers like on image with very small radious? I suppose that cable could not last even a short time. When I did some first test with my easy loder, 2 mm spectra become damaged after very short time being winded on 8 mm shaft, under force of maybe 60 kgf. That is why I changed the OD of the shaft to 12 mm. I used the loader up to 30 gkf, but tested it up to 80 kgf.
 
popgun pete

popgun pete

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Yes, that is right, one cable, even though doubled up at the piston, has to take all that load. If you consider a multi-band gun then there are many cord wishbones to spread the loaded tension over, but this "Dreamair" gun in a sense has one inner wishbone functioning as the single "multi-band anchor". A medium power gun may be possible with one or two axles, but my guess is that it would be inferior in performance to much simpler weapons and would have low reliability.
 
popgun pete

popgun pete

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Lovely pictures!
I am still waiting for a model that has a small diameter barrel mounted above the air chamber....
Unfortunately it has already happened and the chance of finding one now will be slim, the original "Air' Balett".
AIR BALETT advert R
 
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tromic

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I got an idea how this gun might work pretty reliable, but I suppose it is different from authors idea.
If the OD of the piston would be 6 cm then on the 0 m depth due to vacuum behind the piston, the force on piston would be about 28 kgf. On 10 m depth force would be 28 x 2 = 56 kgf. In this design no compressed air would be necessary for operation. Loading of the gun would be very easy because loading on the surface would require only 28 kgf in two steps 14 kgf + 14 kgf (according to design on authors patent drawing). Also, I would make it without variable transmission, just using regular rollers.

1zn0geg.jpg
 
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tromic

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Here is a possibility how it could work:
302udjr.jpg
 
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tromic

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Another (theoretical?) design:

307m9zr.jpg
 
popgun pete

popgun pete

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Friction on a big diameter sliding piston will be a problem, especially if low pressure is used inside the gun to power it. I doubt that the "Dreamair" design will ever be a production gun, too many potential problems areas to derail its performance which will be inferior to much simpler designs even if everything works.
 
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tromic

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Friction on a big diameter sliding piston will be a problem, especially if low pressure is used inside the gun to power it. I doubt that the "Dreamair" design will ever be a production gun, too many potential problems areas to derail its performance which will be inferior to much simpler designs even if everything works.

Hi Pete! Have you a new laptop after burglary?
I think friction would not be very high. At 10 % compression of 4 mm cross section OR, and friction coefficient 0.1 it might be less than 3 kgf. With floating OR design even lower, maybe not more than 1.5 kgf.
 
popgun pete

popgun pete

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Hi Pete! Have you a new laptop after burglary?
I think friction would not be very high. At 10 % compression of 4 mm cross section OR, and friction coefficient 0.1 it might be less than 3 kgf. With floating OR design even lower, maybe not more than 1.5 kgf.
I am using a borrowed computer at the moment, it is pretty slow as it used to use Windows XP, but now runs Windows System 7 with not a lot of spare memory.

The standard of finish in the barrel/tank bore would also be a factor in determining any friction, hence finding suitable tubing for this gun may also be a problem. Pulleys and cables needlessly complicate a design which is going to be of a lower efficiency, so not really much more than a curiosity.
 
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tromic

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Yes you are right about the efficiency. But I like the idea to use a gun without having bands or needing to pump it with air.
With windows 7 you should have at least 2 Gb of RAM. I still use an old pentium 4 computer with xp and 1 Gb of RAM.
 
popgun pete

popgun pete

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I wonder when a gun will be produced and tested, as against the use of interesting computer 3D images and promotional diagrams.
 
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tromic

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From the new image I would conclude that on the left side of the piston is water, and on the right side is vacuum!?
There will be hydraulic ram action on the piston and additional recoil?
 
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