Chief Delphi - Drum shooter?

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Re: Drum shooter?

I agree, a drum, roller, wide wheel, what ever you call it that accepts and discharges multiple balls should work. There will be a trade off between accuracy and width. So, 2, maybe three wide is about the limit is my guess.

Re: Drum shooter?

Quote:

Originally Posted by pipsqueaker (Post 1630485)

Drum shooter is absolutely the way to go (unless anyone can design a high-capacity catapult, 1678?)

I for one would love to see a robot that launches the entire contents of their hopper with one shot of a catapult.

Re: Drum shooter?

Drum/roller shooters work pretty okay I guess...

Especially when coupled with a constantly-recycling hopper.

Re: Drum shooter?

Quote:

Originally Posted by pipsqueaker (Post 1630485)

Drum shooter is absolutely the way to go (unless anyone can design a high-capacity catapult, 1678?)

You leave us out of this! Just because I am well versed in catapults does not mean we can build any catapult.

Re: Drum shooter?

Quote:

Originally Posted by Kevin Sevcik (Post 1630253)

Okay, 74g ball. Call it 8 m/s muzzle velocity. Let's assume rolling without slipping out of the shooter, we'll call it a ring so I don't have to look up inertia of a wiffle ball. So 1/2mv^2+1/2mr^2(v/r)^2. So r cancels and mv^2. Each shot has about 5j. Yes inefficiencies and all that. Say 10% efficiency, so 50j per shot. A properly geared CIM would put out 334W, so 6.5 shots per second without slowing. So with those assumptions, a 2 CIM drum shooter could put out 13 shots per second without slowing.

That math works out but we have to think of things in terms of instantaneous vs average ROF. Back in the bad old days of paintball before the more sophisticated hoppers and good, high flow regulators we would run into this all the time. Your math would run very similarly to what you just did. You then try and implement that solution and you have problems of inconsistent shots or misfeeding. Then you would realize that you only have so much control over your ROF. Very rarely would you be able to get the feeding so that each shot is evenly spaced in time. If your goal is to be able to handle a real world 13 fps average over a load of fuel, you need to be able to push quite a bit more than the theoretical numbers for 13 per second. The reasoning is while your average may be 13 per second over 2-5 seconds, you may see spacings between fuel characteristic of much faster rates of fires. Say, the first 3 might be actually 1/20th of a second between the fuel while the last 3 might be 1/6th of a second between shots because the system feeding the shooter loses efficiency when the hopper gets low.

What I just said starts to fall apart if you have a completely linear indexing system for the fuel where it will not have to go from bulk storage to single file. This means we can index the feeding uniformly throughout the firing cycle. Unfortunately for us, this will reduce the number of fuel a robot can carry per unit volume which is not good for cycle efficiency.

Re: Drum shooter?

Quote:

Originally Posted by viggy96 (Post 1630149)

Does anyone here think it would be reasonable to shoot balls using a spinning drum, rather than a wheel, so that you could shoot 2 or 3 wide?

Our current plan is more or less inspired by 148's 2009 bot, Tornado, (though without the fancy ball storage) (https://www.youtube.com/watch?v=aCVLZFyEI1Y) and we were trying to see if we could put a shooter on it as well, to shoot for the high goal. Being able to empty the hopper faster would be very beneficial.

Instead of doing a shooter that is 2 or 3 times as wide, you could fit possibly two to three shooter that handle one ball each. It can increase your accuracy and may only take up a little more space.