The new diagram shows the connecting cable as Dyneema, the piston (10 square centimetre in area) being an oval shape in what must now be an oval bore. Previously the piston was a cylinder sliding in a cylindrical bore with flanking side tubes that contained pressurized air and were cross-connected to the central tube at the front, the cross-section of the alloy barrel being similar in shape to what is used in the Sporasub "One Air". Otherwise the concept seems to be unchanged, this version having just the one roller axle and cable wishbone. The vacuum at the rear is necessary as if water filled the barrel tubing after the piston advanced against the air pressure in the front end of the gun then on the piston's return journey during the shot the water would have to be pushed out of the tube thus greatly slowing the shot. Thus for the gun to work the barrel needs to be a completely sealed system at both ends, the piston not being exposed to ambient pressure and no air transferring across the piston from front to rear. The dark spaces at the gun ends on the new diagram are not openings to the tubing as the roller/drum axle must be located in the pressurized area and for that reason I think the same applies at the rear end, i.e. it is closed off. Otherwise the gun would have to push a large column of water rearwards when it fired.
The compression ratio of the gun needs to be considered; with air from the central cylindrical bore being forced into the crescent shape cross-section side tanks by the piston forward movement a realistic compression ratio is possible, but if the oval piston version has no side tanks then the compression ratio will be higher. The edges of the tank shown on the diagram may still indicate voids or chambers on the sides, however their volumetric capacity will be reduced by an oval-shaped central bore.
For the investment required in producing specialized barrel tubing and the fabrication of spiral track winding drums or "CVT" rollers the "Dreamair" gun seems an unlikely business proposition given the prospect of low efficiency in its operation and the potential for unreliability where the various cables connect to these drums or rollers.
The compression ratio of the gun needs to be considered; with air from the central cylindrical bore being forced into the crescent shape cross-section side tanks by the piston forward movement a realistic compression ratio is possible, but if the oval piston version has no side tanks then the compression ratio will be higher. The edges of the tank shown on the diagram may still indicate voids or chambers on the sides, however their volumetric capacity will be reduced by an oval-shaped central bore.
For the investment required in producing specialized barrel tubing and the fabrication of spiral track winding drums or "CVT" rollers the "Dreamair" gun seems an unlikely business proposition given the prospect of low efficiency in its operation and the potential for unreliability where the various cables connect to these drums or rollers.