How do we launch this thing? 2014

[MMahoney]

I built a quick prototype pneumatic launcher today and was disappointed by how weak it shot. We did a variety of tests at different angles (~10 degrees, 45 degrees, and ~75-80 degrees) and found that the ball flew about 6-7 feet at highest. Barely enough to clear the truss.

[MrForbes]

Interesting....I saw video of a different pneumatic launcher that today shot the ball briskly into the 10 ft high ceiling.

My guess is that you were not using the best geometry, cylinder size, valve type, or something.

[BenCogs]

I am very interested in seeing this video, could you please link it for us?

[jman4747]

Originally Posted by MMahoney

I built a quick prototype pneumatic launcher today and was disappointed by how weak it shot. We did a variety of tests at different angles (~10 degrees, 45 degrees, and ~75-80 degrees) and found that the ball flew about 6-7 feet at highest. Barely enough to clear the truss.

What were the cylinder specs?

Originally Posted by MrForbes

Interesting....I saw video of a different pneumatic launcher that today shot the ball briskly into the 10 ft high ceiling.

can you link that?

[Canon reeves]

We are planning on using a catapult with surgical tubing as our strength, a hexagon to cradle the ball, and a shift and winch system. We also are planning on having a long kitbot with a high geared six motor drive train. One thing we are also weighing through is our floor feeder needs to be able to take hits and not shear off. And since we plan on having a long base, the ball is wider than our robot so a floor feeder above the ball will be hard to keep within the frame. We thought about two wheels on the side that grab it, than lift it into catapult, this would allow it to start in bumper zone then the feeder shoots down, we drive forwards, shoot, pull feeder up and maybe have three different programs that send the bot to different zones. I think several teams won't plan for this so we might see some breakage. One difference this year is that one robot can do it all (excluding goalie), all that is needed 1st is something that can shoot the ball into the high goal and over the truss, 2nd is the ability to pick balls up off the ground, 3rd is to be able to catch. I am thinking of putting bars up around the hexagon that aid in backstopping and catching, it will also help with defense?

[RRLedford]

Originally Posted by MMahoney

I built a quick prototype pneumatic launcher today and was disappointed by how weak it shot. We did a variety of tests at different angles (~10 degrees, 45 degrees, and ~75-80 degrees) and found that the ball flew about 6-7 feet at highest. Barely enough to clear the truss.

One issue with a pneumatic cylinder launcher is the peak piston velocity being restricted by the rate at which air ahead of the piston can exit the cylinder.

Ideally, the space in front of the piston disk seal would be a vacuum, and offer no resistance. This could be accomplished by sealing both ports of the cylinder with the piston extended.

Then by mechanically pulling the piston back into the cylinder so as to build up pressure on one end and partial vacuum on the other piston exit end, you can make it into a "gas spring"
Releasing the hold on the compressed piston would fire it at a higher speed than when there is air ahead of the piston.

This may not be legal though. There are many safety issues. Too much piston retraction could build up pressure in the cylinder exceeding its limits.
Also, piston can overshoot inside cylinder and impact the head at the exit end, damaging it.

-Dick Ledford