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Unread 23-03-2014, 23:38
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Re: Additional questions about improving pneumatic catapult

Quote:
Originally Posted by TheHolyHades1 View Post
Hello.
4. The pistons start off approximately half extended and end fully extended (they have an 8" stroke).
This is a problem, to get a fast reaction time, you need to have cylinders at the bottom of the stroke. So this is a problem if you are not using a latch and pre-pressuring the cylinder prior to launch.

Think of a drink cup, it has a lid, you poke two straws in the lid, one is the input and one is the output. Put your finger over the output and blow on the input. How long do you have to blow before you can't blow anymore? Now make the cup twice the size, how long? Now eliminate the cup, and hold the other end of the straw. Buy starting the motion with the piston in the middle of the cylinder, you have a large cup between the input and the output. To move the cylinder, you need to pressurize the whole volume to the psi above the load to move. Moving large volumes of air through a straw takes time, reduce the volume reduce the time.

Try to remount the cylinder to use the first half of the stroke and not the last half for speed.

If you go with the latch method, they that volume of air in the cylinder, is basically a low pressure storage tank, which would be beneficial to that system.
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