SpudFiles

So I had this idea for a cannon that worked by having a small wheel driven by a motor the spun in a small groove in the barrel propelling the ammunition out at a him velocity. I was wondering if such a device would work as I think it would be cool to attempt to build one. It works in a similar fashion to how those automatic pitching machines for baseball work, but on a smaller scale. So what do you guys think?

It would work but would have some pretty bad accuracy unless the motors are perfectly tuned like they are in batting machines. Have you heard of the nerf barricade? It also uses this type of propulsion system. A benefit of this would be that you could create hop-up like spin on the airsoft bb by tuning the two flywheels.

jackssmirkingrevenge wrote:http://www.oocities.org/pest3125/pest/pest.htm

Wow, has anyone tried to do this on a BB gun? This looks like another alternative to full auto firing

bookyle wrote:Wow, has anyone tried to do this on a BB gun? This looks like another alternative to full auto firing

It was contemplated as a full size weapon but nothing much seems to have come of it.

[youtube][/youtube]

I believe mythbusters had tried something similar.

Wow! I'm glad you guys have interest in this. Also thanks for posting those fascinating links to the PEST and the dread gun, those are very similar to what I have in mind. So if I wanted to build a device like what I have described, where should I begin?

The video seemed a little sketchy, as there was no animation as to how it would fire, or how it works.

the PEST design seemed like a good candidate, but I'm not sure if it is viable to use on the airsoft battlefield. To fire it, the motor has to be spinned for about 1 sec, not a very fast reaction time.

The motor could be spinning constantly, but that would drain the battery rather quickly, unless you are carrying a car battery on you.

It could work as a stationary turret.

Xenophile wrote:So if I wanted to build a device like what I have described, where should I begin?

- find the strongest fastest spinning motor you can get your hands on, and an appropriate power source

- make sure you are capable of making something that doesn't fly apart

Unfortunately, even for low power with these things you need some pretty high spec hardware, unlike say a cloud BB machinegun, that can be put together from rubbish and still do some damage.

I fully back up JSR's second point; I had a spinning object (made of PVC and metal) blow up on me and it wasn't cool. Make sure you build strong.

This might be of interest, its from a 1963 popular mechanics
http://boingboing.net/images/electricbbcannonme4.jpg

Xenophile

Have you considered the flywheel rpm's you'll need to achieve (based on flywheel diameter) to launch projectiles with even a modicum of speed?

that's an easy calculation, of course the flywheel speed will drop after each shot, the faster you want the projectile the less practical this will be, if I could remember rotational energy formula I could crunch some gestimates for actual muzzle velocities
I've seen plenty example of this in nerf dart launchers like this my guesstimate is that muzzle velocities of less than 150fps (~102mph) would be most practical, but the pest is definitely an exception to that

bookyle wrote:Wow, has anyone tried to do this on a BB gun? This looks like another alternative to full auto firing

I don't know but I think larger projectiles would be more practical

Lombard Centrifugal Gun circa 1918
Read about it in The Browning Machine Gun Vol 1 by Dolf Goldsmith

Claims it would fire 33,000rpm, cannot jam, had no barrel, and go through 3/8th boiler plate at 200 yards. First version was powered by a hand crank, then electric, then steam. It was tested during the US machinegun trials.

In reality, it did not really work that well, all the claims were false.





Lombard worked on the gun for 37 years...

Interesting! Though going through steel plate with something hand cranked is definitely stretching the imagination.

Ultimately, two questions:

1) Is the theory sound?

A: Definitely.

2) Can it be put into practice in a manner that is strong, simple, cheap and compact enough to be able to challenge the supremacy of barrelled weapons?

A: Not now in 2011.

It will be interesting to see what can be done using future materials and propulsion types, but here and now as I said before it takes some relatively high spec construction to challenge even a shíttily built compressed air powered BBMG.