jook13 wrote:I screwed in a screw at the end of my barrel on top. It sticks in about 1/8 an inch. The golf ball catches the tip of the screw a bit then keeps on climbing.

So a little sheet metal or wood screw would work? Are you using the thin 1.5" pvc (sdr-21?) or the sch 80 2" with a burst disk?

I am part of the crowd that says 1800 feet is definately possible with a golfball at 1x. My combustion sends golf balls literally out of site. Of course my barrel is about 9 feet long and I use metered propane, as well as induce some serious back spin. That back spin makes all the difference.

How ...

I think it's believable to fire a golf ball 1800 feet. It's tough to do with ggdt, but it can't simulate backspin. And anyone who has ever seen a golf ball travel in a perfect line for over a hundred yards can tell you backspin is a pretty significant variable.

Therefore, the only way to tell if ...

I think it is the opposite. The narrow opening restricts flow, lengthening the burn time, which means a longer period of pressure.

This was confirmed by advanced simulations.

So what if it was falling sand....

I'm not denying your claim, but do you have a link or a file with the simulation ...

i was trying to model pressure front and what not with that little animation, but if you're good at analysis, you can see past all the faults of what i did and find some at least little useful information

I think there's some useful information to be gathered from your animation. It looks pretty ...

No helmet or protective clothing, steel cage...?.. :roll: Please don't do that again.

Well, not really. I parked the ATV at the edge of the runway next to a large tree. If the ball's heading was in my direction, I took cover. If not I tried to spot the landing. I doubt I'll do it again..... at ...

Aside from the fact that you're using a burst disk and a better fuel, I still can't see a golfball travelling 800m (half a mile) from anything 1x mix combustion. Maybe this venturi effect can make all the difference but it appears he's using the 'spray and pray' method, with a single spark from the ...

Well for starters, he's definitely not shooting 1800feet.

He most certainly is..... (well, 1770 measured via GPS). We shot the balls on a grass runway and the longest ball traveled 1770 feet. Most fell in the 1500 foot range, but consistently over 1500.
I've never heard of a golfball going ...

and gets a lot more distance (around 1800 feet).
Well for starters, he's definitely not shooting 1800feet.

He most certainly is..... (well, 1770 measured via GPS). We shot the balls on a grass runway and the longest ball traveled 1770 feet. Most fell in the 1500 foot range, but consistently over ...

While it would increase the surface area (therefore losing performance to heat loss), the first funnel would create a high(er) speed jet of burning fuel through the gun, as well as igniting the side branches on it's path. This would perhaps eliminate the need for multiple ignition points and a fan ...

So this would increase turbulence and therefore there would be more fuel ignited? its the only way i can see it working...

My understanding of the venturi effect was that it increased the speed of a fluid.. but decreases the pressure...

I guess it's behaving as a fan during combustion (mixing ...

I'm in the process of gathering info/parts for a 2.5" cannon for tennis balls. I've got a friend that has a cannon that he uses to shoot golf balls. In the past, he had a 4" chamber (roughly 20" long) and got good distance using an aerosol propellant (Tag body spray). Now, he uses a venturi shaped ...