Paintball Minigun...

[Evil Bob]

Was doing a search on the GE-M134 minigun and came accross this web site... http://www.montysminiguns.com/paintball.htm.

At the bottom of this page, there is a paintball minigun that looks fairly realistic, there is also a rather poor quality .avi showing both loading and firing. I've emailed the guy who makes it to see if he has anymore info about it. Apparently he's been building them on a per order basis starting last month.

-Evil Bob

[edweird]

Well Brad kayle and I have been shooting around ideas about a real paintball minigun based around the AGD valve. The ball is in brad's court but when I visit his casa in december I hope to lend him a hand on this.

[Wat]

physics

The site says

"Paintball miniguns are not the same size as standard miniguns due to the speed of the rotor & it's ability to pick up a static paintball, accelerate it then spin it in a 4 inch circumference at 1000 RPM all in just a few milliseconds. A paintball cannot handle +20g's in that fashion, even if it is frozen solid"

This is quite wrong. We're firing a paintball from rest to 300 feet per second in say, a 10" barrel.
Time to go metric
300feet = 91.44 meters
10" = 0.254 meters
G = 9.8m/s^2

Using the equation
Velocity^2 = 2 * Acceleration * Distance traveled

Acceleration = 91.44^2 / (2 * 0.254)
= 16,459 m/s^2 or
= 1,680 g

This is assuming constant acceleration in the 10" barrel. This we know is not true, but reality would be that the peak acceleration would be an even higher number.

How many G's does the rotating barrel induce?

I'm going to assume that he meant 4" diameter and not circumference as that would mean a radius of only 0.64 inches. Lets assume 10cm diameter or 5 cm radius.

1000 rpm = 16.667 revs/sec
1 Rev = 2 * pi * r = distance traveled
V = 16.667 revs/sec * 0.1pi meters/rev = 5.236 m/s

centripetal acceleration = v^2 / r = 548 m/s^2 = 56g's

So firing a ball is 1600g's while spining it at 1000rpm in a 10cm diameter rotor is only 56g's.

I think a loading mechanism similar to the AT85rs canceled megaloader could handle this kind of feed rate. What i'd do is have say, multiple loading mechanisms. Instead of having one loader feed every breach, you could have two that alternate.

[manike]

Interesting stuff. I thought about and started designing a minigun once upon a time. Maybe I'll get back to it eventually

I agree with Wat, you should be able to feed it faster and better than they try to make out.

Heck that one doesn't seem to be shooting very fast when it is firing at all...

[Matt_mg]

god... he puts on annoying music and disables right clicking...

The content somewhat redeems the suckiness of the web design

[edweird]

yeah we identifyed the speed of rotation as the primary problem as well... our counter for it is to simply slow it down.

with 5 or 6 active barrels in a system like this even a slow rate of spin will create a reasonable rate of fire.

With scenario rules as they are now this gun design would have to highly held back and require lots of special premission. But for gee wiz purposes just changing it from 3 rotations a second to 4 makes a grand leap of 15 BPS to 20 BPS w/ 5 barrles or 18 to 24 with 6.

Personally I dont worry much about the math of it. Once brad gets his built im sure trial and error will dicticate the outer limits of this... after all we arnt dealing with a real weapons system here and have the flexability to freely test this with no risk at all.

[vf-xx]

I wonder when he'll get a chance to start it. Brad told me about it almost 2 years ago when I was working in houston.

[BradAGD]

yeah, I'm lazy and busy at the same time. I need to get my butt in gear and get this project done. With Tom's interest in scenario games now, this would be perfect for him to make a statement.

If we can just get a motor for the dunebuggy I want to build too, we'll be in business.

and to Kayle...airmotor

laters

[edweird]

Brad... im working the Warthog angle atm... I think this may become my winter project if everything falls in place.

yes... I mean Warthog. (see Puma, Chupathingie, Halo uber truck of doom.)

[BradAGD]

coolio...this is going to be cool.

Guess the ball is in my court now. Better get going on it.

[Matt_mg]

hmmm will you use 6 (or 3 or 4 whatever) bolts or just one?

maybe we should move this to the workshop

[BradAGD]

There will be 6 complete mag valves in the back of the gun. If the gun turns at 720rpm, each barrel will shoot 12bps, thats 72bps overall and 4320 rounds per minute...

[manike]

Damn I need to get on with my mini gun also...

Then Brad and I can face off.

I think maybe we should wear full leather and motorcycle helmets though....

Brad how long till you get yours made? Just so I know what time to try and work within? Sounds like you have started already...

[doc_Zox]

just the thing for a california recall scenario:

http://www.pipersprecisionproducts.com/m134_6mm.htm

[Evil Bob]

No response from Tim Cruz yet, hoping to hear from him soon, I really want to see better video of his mini in action.

For those who want to build their own, you might find the following .mpg's at the bottom of this page inspiring...

Here is the link for the patent info for their M134 BB gun (dated 28 Dec 1998), may be some good info for you guys who are going forward with this project.

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=1&f=G&l=50&co1=AND&d=ptxt&s1='piper+paul'&OS="piper+paul"

(edit - last URL seems to be a tad toooo long to parse properly)

-Evil Bob