Linear Shooters - How did you do it?

[Leav]

My team experimented with a Pneumatic Piston Shooter similar to that of Simbotics but we barely got the ball to clear a 20cm (~8") barrier, let alone the overpass from 2-3 meters away....

How did simbotics or any other similar team make it effective?
(Was it even pneumatic?)

<edit>
Just noticed that Simbotics was not pneumatic - but how did it work?
did anyone manage a linear shooter with pneumatics?
</edit>


just curios...

-Leav

[Matt H.]

The make a linear pneumatic shooter you must latch down the cylinder. By allowing it to extend 1/2way and then latching it in place your manage to store energy to later by used in firing. Similar actuating the cylinder stores very little energy where you need it and hence doesn't shoot the ball very far.

Note: It is actually better to allow the cylinder to extend about 1/3 of the way then latch it for maximum energy imparted. This can be seen by setting up an integral for the pressure vs volume graph.

[Curt Henderson]

Team 1501 took a different approach to the shooter design. We use pnuematic cylinders to pivot a monocoque constructed sail which telescopes out the rails (chrome-moly tubing) to tension surgical that is attached to our sled. A tilting action on the sled is created by the pivoting of the sail which use to pick up the ball for launch. We have posted videos on youtube.com that demonstrates our design. We went in this derection for two reasons, first, as a means to build a safe energy device to eliminate injuries and secondly, it is a cool mechanism that works very effectively.

We also have a unique device to remove the ball from the overpass which we have intensionally kept from display.

[Leav]

Very cool robot from 1501: http://www.youtube.com/watch?v=D5OC-Y-af74

just to satisfy my curiosity: are any teams using pneumatic pistons to directly launch the ball?

-Leav

[Dgrez]

Team 612 uses two pneumatic pistons to directly launch the ball and it is rather effective. They drop out once the elevator reaches the correct height and fire.

http://youtube.com/watch?v=VbGBxKjMlh0

[dpc131]

We have a different approach. We are using two 2" Cylinders to put force into compressing a set of springs. We then latch the springs and retract the cylinders to prevent them from dampening the spring force. Lastly, we release the latch and use the spring energy to fire the ball.
http://www.chiefdelphi.com/forums/at...0&d=1203646429

[AndyB]

For the sixth time...


Simbotics does not use pnuematics to shoot the ball. They tension it using surgical tubing and wind it back with a motor. The only pnuematic shooter I saw was 1024. The lifted the ball to about a 5' level before shooting it with what appeared to be 4 3/4" bore pistons.

[martin417]

Team 1771 uses pneumatics to launch. We are acquiring and holding with a vacuum device. When we launch, the vacuum holds the ball until it develops sufficient force to break the vacuum. It works very well.

Video here:

http://www.youtube.com/watch?v=QeQSGmFnKAE

More details here:

http://www.chiefdelphi.com/forums/sh...highlight=1771

[Jherbie53]

I believe we are using either 2" or 1 1/2" bore cylinders, most likely the 2" bore, that have a 6" stroke. We used three storage tanks right before the cylinders, they all tie together after the valves. I don't have any good pictures, but I do have a youtube video.

If you want to see us on a field, you can watch our matches from St. Louis on the blue alliance site.

[1086VEX]

we (1086) uses 4 8" stroke 3/4" or 1" bore(im not sure) pistons to launch the ball. we can launch the ball around 10' in the air and a pretty far distance as well (like over our overpass from our opponents side of the field ). it just took some time to find the right hight for the launcher and the right angle for the piston mounts. it is deffinetly very effective.
you can check us out this weekend at VCU!!

[JesseK]

Originally Posted by 1086VEX

we (1086) uses 4 8" stroke 3/4" or 1" bore(im not sure) pistons to launch the ball. we can launch the ball around 10' in the air and a pretty far distance as well (like over our overpass from our opponents side of the field ). it just took some time to find the right hight for the launcher and the right angle for the piston mounts. it is deffinetly very effective.
you can check us out this weekend at VCU!!

Yea I'll come check you guys out tomorrow. Can't figure out how any of this pneumatic launcher stuff works. It seemed like all of our prototypes of a pneumatic launch were just doomed from the start.

[gurellia53]

We're using 2 CIM motors to launch. I guess everyone else is afraid of them.
Is ANYONE else using motors to launch?

And...
here's a video: http://youtube.com/watch?v=NfoPwtG1UGI

some pics:
http://www.chiefdelphi.com/forums/sh...ad.php?t=64406
http://www.chiefdelphi.com/media/photos/30380

[thefro526]

At the end of the season I kicked around building a trackball catapult as a possible project in school and the way I was going to do it was to have a piston retract the catapult and pull some surgical tubing tight. to get the piston to extend with the surgical tubing fast enough I was just going to leave one of the ports open which effectively makes it a spring return style piston. I figured that when you switch the direction of the piston it will almost instantly compress and shoot the ball. I'm not entirely sure it would work but if it did it would be kinda cool.

[jfc358]

Originally Posted by Leav

My team experimented with a Pneumatic Piston Shooter similar to that of Simbotics but we barely got the ball to clear a 20cm (~8") barrier, let alone the overpass from 2-3 meters away....

How did simbotics or any other similar team make it effective?
(Was it even pneumatic?)

<edit>
Just noticed that Simbotics was not pneumatic - but how did it work?
did anyone manage a linear shooter with pneumatics?
</edit>


just curios...

-Leav

We originally had a linear cylinder on our arm to push the ball over the overpass. We did some tests with different cylinders, but were not happy with the results. We never tried the latching technique as we decided to build a "drop kick" device. This mechanism used a 1 /12" bore cylinder to kick the ball shortly after it was dropped from our arm. After some debate, and some time lapse photos we realized we had more of a Jai-alai stick. After a few small modications, we came up with a result we much happier with. This mechanism allows us to throw the ball from about 8 feet from the overpass, while we are moving. This gives us enough time to drop and go under overpass without slowing down. It also turned out to help us cradle the ball, before the pickup. This video has been posted before, but for those of you who haven't seen this:

We can't wait for CTR later this week.

http://www.youtube.com/watch?v=N1BZAsH-RYA

[danshaffer]

we use a plain pneumatic shooter, with a twist: a lever arm for a 7:1 mechanical advantage, so that we get more speed and less force.