Creating pneumatic launchers

[ToddF]

Originally Posted by billbo911

Perfect example.
1 1 1/2" dia. cylinder with 60psi of air pressure applied produces 106Lb of force.
2 1 1/6" dia. cylinders with 60psi of air pressure applied produces 106Lb of force.

Note that with the same stroke length, it takes the same volume of gas to fill both of these configurations. With only a single solenoid valve supplying the gas, they fill in exactly the same time. The thing that allows the second configuration to fill faster in a FIRST robot is the ability to use two valves to fill the same volume.

In the real world, using a single large cylinder and filling with two valves would be more weight efficient than the second configuration mentioned. I hate seeing people tossing around generalities like "larger cylinders are slower" without stating the underlying assumptions behind the specific application that makes it so. I fear we're teaching our students design "rules" which are only true in the restricted world of FIRST robotics, but are completely reversed in the real world.

Another approach would be to use the single cylinder from configuration 1, and use a faster flowing valve, a perfectly valid option this year. People are finding legal valves with more than twice the flow capacity than previously legal valves.