Re: Best Way to Shoot the Balls??
 

One of my teammates had the idea to have two spinners (like in old Hot Wheels tracks) in the barrel to accelerate the ball and prevent spin from killing accuracy.

Re: Best Way to Shoot the Balls??
 

Actually a spin on the ball will improve accuracy, probably backspin or spiral would be the best. In baseball the erratic behavior of a knuckleball pitch is due to the fact that it has little or no spin. It has to do with turbulence of the air around the ball, but since I don't use that stuff at work (and its been a LONG time since I was in school) I am unable to regurgitate any specific details.

Re: Best Way to Shoot the Balls??
 

Really? I assumed that, if you spun the ball one way, it would veer off to one side once out of the barrel. Or you could make a long barrel, which would have problems of its own. Maybe it was my analogy at one meeting that the balls were like musket balls. Maybe I just need more sleep.

Re: Best Way to Shoot the Balls??
 

I agree with Eria, because when you think of spin on something like a football, that helps to prevent different faces from being on the front, and thus pose different amounts of drag, causing the ball to tumble even worse. In the case of one of these balls, it is unclear if it will act like a baseball, because these have far less mass per unit of volume, and thus when accelerated have less momentum keeping them going forward. As the physics aren't totally clear, I asked my physics teacher about it, and he said to stay away from spin on this kind of ball. He didn't see the exact ball though, and I think the most definitive way to know how the ball will react to spin is to mock up a shooter and try it, which is what my team hopes to accomplish this weekend, among a million other things.

Re: Best Way to Shoot the Balls??
 

More video footage of Poof Balls being launched through a flywheel.
Our team borrowed the volleyball serving machine from our athletic department and you can see the footage HERE.

Re: Best Way to Shoot the Balls??
 

617 has so far made a prototype with AC drills driving the top and bottom wheels on the softball-style shooter, with the top one smaller than the bottom wheel. The bottom wheel was the 12ish inch pneumatic wheel from two years ago, and the top "wheel" was two 5 inch diameter wheels duct taped together on a shaft so that there was a depression between them. The speeds that we shot at were right around max depending on the speeds of the wheels. We got some major backspin and can hit the goal's center consistantly from midfield.

Good luck to all.


<edit>
we have a 4-inch wide channel to feed the ball through the shooter also. that probably helps with the straightness of the shot.
</edit>

Re: Best Way to Shoot the Balls??
 

ditto

Re: Best Way to Shoot the Balls??
 

We thought about rifling which could be introduced by a series of small, slightly angled, opposing wheels, but realized there is a problem. These balls are not equally balanced. They always roll to their heavier side where the injection point is. Spinning the ball will most likely produce an unpredictable wobble depending on where that heavier side is when it goes through the shooter.

The Trebuchet would definitely be cool, but difficult to load! The counter weight is a problem too. Maybe a dangling compressor.

Re: Best Way to Shoot the Balls??
 

whilst we are not using the catapult it would be pretty cool if someone did
and it wont be that bad of mechanism
it will be VERY percise, but will only shoot I guess 2-4 balls in 10 seconds

the thing is we wanted to do it like a gear in a car, it shoots, but the motor leaves the catapult when it hits the angle, so it falls back down (after it hits a bumper or whatever also)
we didn't go that way eventually
but it would be cool to se someone do it =)

Re: Best Way to Shoot the Balls??
 

We have some major backspin as well, but without a wheel moving on top... In our case the backspin also causes a very accurate shooting mechanism. There was no need for extra barrel.