Cannon Design!!!!!! >_<;

[James Slemons]

Originally Posted by Vikesrock

Another potential issue is compression.

I too think that is your problem there.

Back in 2006 we were prototyping shooters and ran into the same problem. The balls just spat out instead of shooting them and after moving the wheels closer together they went flying.

[XXShadowXX]

Paddle wheel is my solution, instead of compressing the ball it pushes it from behind, and since it's a circle it can reload faster then a pneumatic ram.

With wheels on the side you need at least 2, one for each side, if your using belts you can get away with one since the ball will be in contact for a longer time. The main issue with the wheels is friction (again!), compressing the balls increases the force of friction (which your going to want maxed out), so you might want to rap the wheels in hocky tape or velcro to increase friction between ball and wheel

[EricH]

Originally Posted by XXShadowXX

With wheels on the side you need at least 2, one for each side, if your using belts you can get away with one since the ball will be in contact for a longer time.

No, you don't. 1 will do just fine, if you have a back plate to compress against. 2006 showed that. Contact time has little or nothing to do with it.

I was thinking a bit (dangerous, I know), and had a thought: What if most of the chute didn't rotate, but just the top part did and had the launching wheels close to it? You could run a belt up to the top and have a slower launch speed because you no longer have to fight gravity for the full distance. You also have the ball moving when it comes in, so there is less motor speed loss, and you can shoot faster.

[ZakuAce]

This sounds a lot like what we're planning on doing. We used the 8" andymark traction wheels to shoot it up, with what I'm thinking is about 1 inch or so of compression. We're driving it with a 32 teeth drive sprocket and the sprockets on the wheels are whatever they come standard with. The gearbox is a banebots 4:1 planetary. I'm are trying to get a bigger (more teeth) drive sprocket, but I haven't found anything yet. I don't even know where we got these 32 tooth ones. We haven't tried shooting them up a chute yet, as we don't have material yet to prototype that. We got to shoot it vertically about 8 feet or so. Seems to be fairly consistent. Hopefully we can find something to prototype the chute with Saturday, because I'm worried about being able to actually get the ball out of the chute. I don't think we have quite enough power yet behind the launcher.

BTW, we also direct drove them from the cim motors. Don't do that. The speed is ridiculous, and it could probably throw the orbit ball a long way, but I bet the ball would get destroyed in the process. It already looks pretty battered.

Originally Posted by EricH

No, you don't. 1 will do just fine, if you have a back plate to compress against. 2006 showed that. Contact time has little or nothing to do with it.

I was thinking a bit (dangerous, I know), and had a thought: What if most of the chute didn't rotate, but just the top part did and had the launching wheels close to it? You could run a belt up to the top and have a slower launch speed because you no longer have to fight gravity for the full distance. You also have the ball moving when it comes in, so there is less motor speed loss, and you can shoot faster.

I was thinking about this as well, but mounting the motors and getting it all situated seems like it would be somewhat more complicated. If you just use the chute to direct the orbit balls, it can be extremely light, make of thin aluminum that could save you a decent amount of weight compared to mounting it on top of the chute, which would have to be made out of much stronger material.

[Kraftyman]

Greetings,

Try using 4 of the previous years traction wheels. Two by two really keeps the ball cruising and helps pick them up out of whatever hopper you have to store these things. I agree that the CIMs should not be used directly, as we had some trouble today. A geared or belt system running both sets of wheels will keep them spinning at the same speed and at reasonable speed. Direct drive with the CIM motors could clear 15 feet in our test, but that just bounces of the center post in the trailer. Good luck!!

[wilsonmw04]

Originally Posted by EricH

No, you don't. 1 will do just fine, if you have a back plate to compress against. 2006 showed that. Contact time has little or nothing to do with it.

From a Physics standpoint I'm not sure that argument holds water. With all things being equal, the amount of time that I apply a given force will directly affect the velocity of an object. The more time I have to apply the force the faster the object will travel. For example: compare the muzzle velocities of a pistol vs. that of a rifle.

[EricH]

Originally Posted by wilsonmw04

From a Physics standpoint I'm not sure that argument holds water. With all things being equal, the amount of time that I apply a given force will directly affect the velocity of an object. The more time I have to apply the force the faster the object will travel. For example: compare the muzzle velocities of a pistol vs. that of a rifle.

True. However, we are dealing with relatively short range, low velocity objects. As 2006 showed, teams that don't have a lot of contact time are about equal to teams that have more for this type of application. Especially this year...

From a practicality standpoint, it doesn't really matter. Use a rifle at 10 ft and a pistol at 10 ft. Sure, the rifle gives more speed. But at that range, the pistol is just as effective. Extend the range to a mile and the rifle wins, but we aren't talking that range here, we're talking a few feet.