Help Building "V3" advanced combustion

[Combustion Monkey]

I agree with everything starman and Radiation have been saying. I just wanted to add that since you live in an area thats as cold as I do to consider this. If your tank is putting out between 90 and 110 psi at room temperature and your meter is setup to run at 60 ish psi, by the time your tank pressure drops to the point that you cant hit your meeter pressure its probably time to go in and warm the cannon up anyhow. As you probably know, cold temperatures make PVC brittle.

[metallover]

At 'Da Monkey, I plan to hold off doing most of my shooting until the summer. It's surprisingly hot here in the summer and can get over 100 a few days.

I thought about my propane meter today and I think I can use a 1/4" ball valve and some 1/4" elbows in place of some of the 1/2" pipe.

If you look at my cannon, The meter goes into the chamber at 1/8", then bumpes up to 1/4", and then finally goes up to 1/2". I can change everything from that to the T into 1/4" fittings and put a ball valve right before the 1/8" reducer. do you think that should work?

[starman]

If you look at my cannon, The meter goes into the chamber at 1/8", then bumpes up to 1/4", and then finally goes up to 1/2". I can change everything from that to the T into 1/4" fittings and put a ball valve right before the 1/8" reducer. do you think that should work?

Changing it to 1/4" will make the volume drop by 1/4 the previous volume...maybe going to 3/8" would be a better choice.

Oh and...be sure you measure the exact volume of your meter with the liquid method. For instance, 3/8" iron pipe is actually 1/2" ID.

[metallover]

3/8" going once!

Edit - Some paint skills. this is what I'm planning.

Fuel tool estimates - 125ci chamber, about 8" of pipe

53psi at 3/8" and 88psi at 1/4". I think 3/8 should do nicely. I would take my numbers as a ballpark estimate...

[Radiation]

Looks good, sounds good. Make it happen!

[metallover]

Ok final draft I will have a 1/2" ball valve going directly to the T which will have the preassure gauge and another 1/2" ball valve on the other side. On fueltool I got about 75psi.

I think I'll try it with a 90* street angle between the T and the preasure gauge at first which will bring it back down to abut 55-60psi. I don't know why but I'm worried I won't be able to have enough preassure.

I'll post some pics when I get it finished.

[starman]

To be sure you can fuel in cold weather, shoot for something in the 50-60 psi range. On a 50 degree F day, you'll find 75 psi to be barely achievable.

[metallover]

I got the meter finished. I'm going out shortly for some testing. Temp is 39f. It's NICCCCE out!

Old meter-


NEW meter



It's not centered perfectly but I'll fix that. It's also a little long for my liking but it should work great. If I can't get enough preassure I might go back to that pvc u thing I made.

[metallover]

I got about 10 shots off today. It was a little too loud for my liking. I shoot at the edge of town but I still have lots of neighbors.

As for performance, it was amazing. It performed much better than my old one. I shot at about 40psi. This is a good preassure imo. It is high enough and not all that low. I might try to get it higher once it gets warmer. I could only get about 45 if I waited awhile.

Tamp was about 45, maybe 50 in the sun. I tried firing it a little while ago, but it didn't work too well at all. I could only get maybe 20psi out of it as it had dropped to the freezing point.


Any suggestions to make it quieter? Do you think I can extend the barrel by about a foot using a coupler?

[Radiation]

You could add a coupler with no problem. Generally speaking if your gun is working at 40 you're not going to get any more from a higher psi. Propane has a very narrow window of functionality. in other words figure out what your exact psi requirement is at maximum firing ability and stick with it.

[starman]

Any suggestions to make it quieter? Do you think I can extend the barrel by about a foot using a coupler?

Longer barrel (actually more barrel volume) is your only option short of a silencer of some sort. You can actually get barrels so long that all you hear is the projectile and air speeding out of the end. The upside of a longer barrel is more velocity. The downside is, well, it's longer.... tendency to bend, harder to support and keep straight, harder to transport, etc etc.

Nah, you're pretty much stuck with the noise you have. Learn to love your noise, it can't help it....

[inonickname]

I'd just dodge a silencer..it's a legal black hole. If you want to make one, make it discrete (try make it look consistent with the barrel, not a larger diameter etc..)

[Combustion Monkey]

I'm glad you got it up and running! Now your into the inevitable and perpetual tinkering and tweaking faze. As for the noise, anything that would dull the report to a tolerable level would most likely be larger than you may want to cope with. There are many threads here discussing that. Now you like myself just need warm weather and fresh targets!

[metallover]

I've got lots of updates on this. Today I woke up and there was 3" of fresh snow on the ground at about 11:00. By 4:00 all the snow was gone and it was 60 degrees! 8) I got some shooting and picture taking done today and a little a few days ago.

The propane meter is working pretty good. A good shot is at about 35psi. Now that it's getting warmer I might take the fitting right before the preassure gauge off to take some volume out of the meter.

BUT I can answer questions later. Here are some pictures and videos









A crappy vid -

A short vid -

[Radiation]

That barrel is absurd and beautiful. Good stuff. You must have nice neighbors.