Ha, I spend all that time writing it out and someone beat me to it and more succinctly at that! Serves me right for being so wordy.
Quote:
Originally Posted by DonRotolo
Take two hypothetical 2" cylinders, each 30" long, using 60 PSI air and a solenoid valve for each. You have 8 large plastic storage tanks, fully charged. I am guessing it will take 15-40 seconds to fully retract those cylinders. Assuming you didn't run out all the air extending them....
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I just tossed this into our spreadsheet calculator and it's lots faster than 15 seconds in practice. Even at a very slow 3 GPM, it's going to take ~8 seconds or so to travel either direction. Flow rates of air are pretty dang high:
http://rapidairproducts.com/flowrate.asp
The solenoid is absolutely the slowest part but I think what limits most teams pneumatic speed is that they under tank the system. The pressure differential is a big part of how fast air will travel from the high to low side. When you have a lot of volume to work with in tanks and the differential stays high consistently, you get very speedy air flow and movement. It's when the differential gets low that things start slowing down very quickly. To make it worse, the compressors we use in FRC are very small and slow so assuming they can keep up with large cylinders is a huge mistake.
-Mike