1212 pneumatic catapult prototype

[azcalg]

Originally Posted by Dave Otis

Any advice based on your successful launch?

I didn't do the pneumatics on the prototype, I just built it with some others, so I don't know a whole lot about pneumatics but from what you said, you may need to either use more pistons or a bigger piston. Your setup actually sounds pretty similar to our initial attempt, after which we got it shooting better with a larger piston, after which we got it shooting better with multiple smaller pistons. Sorry I can't help you much on the pneumatic side of things. On the mechanical side, however, I can help a bit more. If you need more speed, you can either attach the piston closer to the pivot point or make the catapult longer. If you move the piston half the distance closer, you will get twice the speed but it will require twice the force. Another idea is to make the angle between the catapult and piston smaller. As Jeffy said, it seems that the pressure builds before it shoots like this. I made a picture for you

[Hoffer5236]

Originally Posted by falconmaster

Here is our pneumatiuc shooter
http://www.youtube.com/watch?v=fljCP...ature=youtu.be

How did you get the varying pressure for the pistons to make them shoot different heights? We cannot figure out how to do that.

[Ether]

Originally Posted by Hoffer5236

How did you get the varying pressure for the pistons to make them shoot different heights? We cannot figure out how to do that.

I wonder if you could treat the solenoid like a MOSFET and PWM it. Has anyone ever tried that?

[Oldbikerider]

Originally Posted by Ether

I wonder if you could treat the solenoid like a MOSFET and PWM it. Has anyone ever tried that?

This is how the turbo boost control works on my Subaru. Or at least how it used to work before I built my own boost controller.

A quick test should show if the valve can respond quickly enough - listen for the chatter and find the frequency it stops chattering.

Another idea for catapult distance adjustment would be to open the valve for a varying time. A slower valve that cannot be pwm'd may still be fast enough for one opening and one closing within the filling time.

Graham.