Best way to get more oomph in pneumatic retracts
When working with heavy retracts, what's the secret to getting more bang for your psi? Multiple valves, i.e. one for main and another for nose gear or even one valve per wheel? Larger diameter tubing? Smaller tubing? Which seems counter intuitive, but I know BVM uses that tiny 2mm tube and it still works on large models like the 1/5th F-16 and F/A-18.
I don't want the gear to slam up and down, but I do need a little more power to raise some stout gear. And I've seen some larger planes with heavier gear operate flawlessly with a pneumatic system so I know it can be done, but what are the best practices when working with such a setup?