Quote:
Originally Posted by Zephyranthes
So I did some math calculations and I found some interesting results. I wanted to see if bore-up cylinders were really necessary for long barrels like thePSG-1 (650mm). The volume of a barrel using the equation for the volume of a cylinder V=pi*((d/2)^2)*l, where d is 6.05mm and l is 650mm. I found the volume to be 18685 cubic mm. I then took measurements of an AEG cylinder (check me if my measurements are wrong), and I found the diameter to be 24mm and the length to be 72mm. Using the same equation above, I found a cylinder's volume to be 32572 cubic mm. That means a type-0 no hole cylinder has 175% the volume of the longest barrel on the market. This makes me question why bore-ups are necessary, considering their purpose is to increase the cylinder's volume to fit the barrel. However, I understand the entire volume of the cylinder is not used because the piston head and cylinder head take up some room inside the cylinder. I also understand that aeg's are not 100% efficient. This still doesn't justify to me the need for a bore-up cylinder when it's volume is 75% more than the barrel. Cylinder volume should not be an issue even with these considerations.
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Many people have done your same calculation and have come to the same conclusion, however:
1) You are not factoring in the "dead" volume of air between the piston head and the tip of the nozzle (when extended) where it touches the BB.
2) You are also assuming a perfect system with zero air loss due to air seal inefficiencies. A lot of air is lost due to such inefficiency. Losses occur around the piston head, the cylinder head, the connection between the cylinder head and air seal nozzle, between the nozzle and BB, and finally, air escaping around the BB as it travels through the barrel.
Your assumptions are only theoretical, but practice shows that in real world scenarios, bore up cylinders ARE required for barrel lengths that long.