Why use a manifold?

[ollien]

Originally Posted by GeeTwo

Based on some number crunching I did during build this year, it appeared that the fastest cylinder performance would be to have a large tank (at least twice and preferably three times as large as the cylinder capacity) on the working pressure side of the regulator, then feeding directly from the tank to the solenoid valve to the cylinder. We did not get to test this, as it turned out the valves we were using had much too low a cv for this to make a difference.

Is there a reason for this? I had heard this once our season ended and I was annoyed that we hadn't tried it to fix our shooter.

[GeeTwo]

Originally Posted by IndySam

I can tell you from experience this is true. This is how we plumed our soccer ball kicker on our Breakaway bot and it made a big difference.

Always good to know that the math gave the right answer!

Originally Posted by ollien

Is there a reason for this? I had heard this once our season ended and I was annoyed that we hadn't tried it to fix our shooter.

Essentially, the air on the working side of the regulator is already there, ready to work. The air on the high side has to filter its way through the pressure regulator, which is not as fast. The tank needs to be significantly larger than the working piston so that there is not too much pressure drop in the supply during the stroke.

Also note that if you are going for a fast stroke, your cylinder should be large enough to move the load (slowly) at a rather low pressure, somewhere around 35psi/(desired acceleration + gravity), with acceleration measured in gees. There will be around 20 psi drop going through the solenoid valve, and pressure reduction as the cylinder extends (or retracts); the remainder is F=ma. (I am assuming here that your fast stroke is for the purpose of working against gravity to throw a ball or other object.)