Paintball

[wingbatwu]

Originally Posted by alpha434

Is this the right thread for this conjecture?

I was, in a non-obvious way, responding to the video posted at the start of the thread... you don't see the round spin that much.

[PistolRogue]

Originally Posted by wingbatwu

I was, in a non-obvious way, responding to the video posted at the start of the thread... you don't see the round spin that much.

It spins up once it leaves the barrel. Since you only see the first few feet it hasn't had much time for the spin to accelerate. Without a high-speed of the round impacting at range it's a little premature to guess at its ultimate rate of spin.

[wingbatwu]

Originally Posted by PistolRogue

It spins up once it leaves the barrel. Since you only see the first few feet it hasn't had much time for the spin to accelerate. Without a high-speed of the round impacting at range it's a little premature to guess at its ultimate rate of spin.

So what we are missing is someone who has access to a Phantom high speed camera, and is willing to film the last few feet in front of a target shot with FS rounds?

[tymcneer]

Sounds good... Now all we need is the camera

Ty

[alpha434]

I don't think it's premature to guess...

The rate of spin at 20 feet out is equal to the flute angle on the fins.

Boom.

What was the question?... Oh. How can we get the round spinning at speed before it leaves the barrel?

[tymcneer]

More verbal surgical precision, Alpha

I have the twist rate calculated, but I want to do some other tests.

I am considering building a small CNC lathe/rifling machine to further this discussion. I will have the cash available in a few days.

Ty

[wingbatwu]

Originally Posted by alpha434

What was the question?... Oh. How can we get the round spinning at speed before it leaves the barrel?

I also had the nutty (genius?) idea of a spinning barrel... imagine if a cordless drill had sex with a paintball marker and had a weird-*** child...

[Nightstar]

Tom Kaye did that back in the day though I don't think he used a cordless.

I was dreaming up a way to do this. A bycycle headset spaced to the ends of the barrel/freak insert and an air tool turbine in the air path of the marker's discharge. Voila!

Now one of you skilled airsmith/machinists go make it.

[alpha434]

If you can tell me how to make it, without ever using the word 'just' or the phrase 'all you have to', then I can make it for you.

[Nightstar]

All you have to do is just remove those limitations and I can describe the mechanism easily.

I'll try to do it within the limits imposed.

The barrel suspended between a pair of bearing races probably doesn't need any explanation. Bicycle headset races because they are available inexpensively in high quality and about the right ID.

As for the spin drive I envision a pneumatic die grinder turning a rubber wheel tensioned against the side of the suspended barrel.

The trick is timing the spool up with the shot, as well as determining what pressure and volume is required to produce the desired RPM. Perhaps separate air circuits with independent regulators and dump chambers so that timing and RPM are adjustable independent of the projectile propellent. Bolt position times the spin by triggering a discharge either mechanically or via hall effect.

Alternatively we could wind a constant force spring using a gas powered cyclone type mechanism with a release tripped by a sear in the bolt path.

I probably made myself clear as mud :/