1212 pneumatic catapult prototype

[azcalg]

http://www.youtube.com/watch?v=YDuA0...ature=youtu.be
So we actually improved it after I took this video but I didn't record it. The metal bit in the middle is the height of the goal.

[Jeffy]

Very Nice!

Did you select that starting angle for the cylinder on purpose? It seems like a good way to get around flow restrictions without added mechanisms.

It seems that is is what is happening:
1. The cylinder has a very short lever arm at the starting stage
2. Because of this, pressure must be very high for the cylinder to start moving
3. Once the arm starts moving, the cylinder gains leverage (the lever arm is longer) and moves the ball very quickly.

[azcalg]

Originally Posted by Jeffy

Did you select that starting angle for the cylinder on purpose?

To be completely honest, we chose that angle because we didn't want to make it any taller or it'd be harder to herd the ball (and a bit of laziness on our part), it was really just a happy accident. And your comment actually enlightened me as to why our other attempts weren't working so well, thanks!

[Donut]

Looks nice, I've wondered how the pneumatic launchers that worked in 2008 got the pressure build up needed for a quick fire without any fancy mechanisms and that video gives a good view of it.

[Jeffy]

Originally Posted by azcalg

To be completely honest, we chose that angle because we didn't want to make it any taller or it'd be harder to herd the ball (and a bit of laziness on our part), it was really just a happy accident. And your comment actually enlightened me as to why our other attempts weren't working so well, thanks!

Glad I could help! Thanks to you for posting the video!

[Hoffer5236]

This is really impressive. My team is also using pneumatics, but we have two with long arms. We're still trying to figure out how to decrease the length while keeping the power. Currently we have two c-channels as arms and a stainless steal rod for the basket. You guys seem to have figured out and it's awesome.

[Uncle Paul]

Thanks for the video and information. Any chance you could provide the spec's on the cylinder you used? Stroke, bore, etc?

[safiq10]

I'm in awe right now that was just fanstatic keep up the good work.

[falconmaster]

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

[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.

[azcalg]

Originally Posted by Uncle Paul

Any chance you could provide the spec's on the cylinder you used? Stroke, bore, etc?

Unfortunately, I'm at home now and we don't meet till Friday so I can't be terribly specific. Today we changed it so it's 2 11 inch pistons with 1.5 inch diameters, but that's all I remember, we actually hit the ceiling with that setup. The one in the video is pretty beefy, if I were to make a rough estimation, it's around 15-20 inches long with a 3 inch diameter, I don't know beyond that, we did this fairly haphazardly without any calculations or anything and just stumbled upon something that worked.

Originally Posted by falconmaster

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

Wow! That's very impressive you guys got it to work so well so early, thanks for sharing

[Hoffer5236]

Here is our shooter: http://youtu.be/r-9v9loC2As. Right now we are trying to make it shorter, and we don't really have a way to do that. Currently the cylinders on there are bimba 1.5in's, but I'm not sure the stroke on them.

[Trey178]

Originally Posted by azcalg

http://www.youtube.com/watch?v=YDuA0...ature=youtu.be
So we actually improved it after I took this video but I didn't record it. The metal bit in the middle is the height of the goal.

What is your supply set-up like? What was your air pressure and what solenoids did you use for such quick air flow?