SpudFiles

Hi all,

back in the day when i was just starting out in spudguns i built a 9' long ball valve GB gun. Now as you can probobly imagine the power was not that great because of the 2" pvc ball valve

so..it leads me to this, go fork out 70$ for a 2" sprinkler valve (of which i need ideas for a pilot, preferably a manually operated one) or go with a 1" sprinkler valve.

Would i get decent power with this as 100 psi with the latter? Or would the flow of the 2" blow it out of the water?



the pipe for the chamber is rated to 18 bar and so is all of the fittings including the 2" to 1.5" reducing bell.

I know there is massive primer stains and even glue stains on it, but it was my first pvc welding job so bear with me.

Before you go telling me to make a piston, my resoning is i want to keep it as an inline and also i wish to make a smalller PV before i attemp at 2" porting one. I also do not wish to purchase of the net so no maulers or supahs for me.

Remember that area and therefore flow increases exponentially with diameter, therefore a 2" port has 4 times the flow of a 1" port, food for thought

yea forgot bout that JSR, who would know what to pump into GGDT for a 2" sprinkler valve?

Should get some decent power aye

Carlman wrote:Should get some decent power aye

Well if this is anything to go by

--

if you want it inline go ahead and make a coaxial;)

or if you has something against pistons do as dewey said but i would go with coaxial since it is an easy build and will give you more power

I still get decent power with the <A HREF="http://www.spudfiles.com/forums/viewtop ... 8">SG-V</a>. Have never measured the distance but looks like it shoots around 200 meters.

Hi

JSR, one little thing:

Remember that area and therefore flow increases exponentially with diameter

Naaah not quite. Area grows by the square of the diameter. Exponential growth is faster.

Example:

[n, 100 * n^2, 2^n]:
[0, 0, 1]
[1, 100, 2]
[2, 400, 4]
[3, 900, 8]
[4, 1600, 16]
[5, 2500, 32]
[6, 3600, 64]
[7, 4900, 128]
[8, 6400, 256]
[9, 8100, 512]
[10, 10000, 1024]
[11, 12100, 2048]
[12, 14400, 4096]
[13, 16900, 8192]
[14, 20400, 16384]
[15, 22500, 32768]
[16, 25600, 65536]

(the exponential function eventually outgrows the quadratic one, even if multiplying that by 100 .. (or any other number))

OK never mind....

(ever thought of why the standard sizes of fittings are about what they are? For each bigger size, the area grows by about the square root of 2. Going up 2 sizes doubles the area).

Carlman I'm afraid you can't get a golf ball into a 40 mm pipe. The ball is 42.67 or something like that. But build the gun anyway; 40mm is a good size, not too big (expensive, lots of pumping etc) and not too small (boring).

I have shot golf balls with an 1" sprikler and a 50mm barrel. It worked ok but it could have been better. Anyway shooting almost vertically the GBs got so high up that they were really hard to find again. I think an 1" sprinkler could perform very well with a 40mm pipe (its ID would be 35mm or so). You could try with an 1" first and then maybe try building a piston valve. The metric parts are wonderful for using end caps as pistons...

Regards
Soren

@dewey-1: Thanks for your input, like the Shock and Awe my valve comes to a point that would suit a 3/8" ball valve perfectly. The picture you posted looks like the pilot flow is constricted to 3/8" anyway so flinging open an easy ball valve shouldn't give that much of a performance drop.

spudfarm wrote:if you want it inline go ahead and make a coaxial;)

or if you has something against pistons do as dewey said but i would go with coaxial since it is an easy build and will give you more power

The point of getting this valve is to use the pipe i all ready had. The chamber is really thick and the barrel only just slides inside it, so no coaxial for this one .

MrCrowley wrote:I still get decent power with the <A HREF="http://www.spudfiles.com/forums/viewtop ... 8">SG-V</a>. Have never measured the distance but looks like it shoots around 200 meters.

I have seen your cannon before, at say 100 psi what thickness ply could it go through? The 1" seemed to have worked for you there but all i wonder is going with the 2" going to make a big difference.

dongfang wrote:Carlman I'm afraid you can't get a golf ball into a 40 mm pipe. The ball is 42.67 or something like that. But build the gun anyway; 40mm is a good size, not too big (expensive, lots of pumping etc) and not too small (boring).

I'm afraid i can get a golfball in 40mm cpvc pipe

It fits so well that if you block off one end of the barrel it will take approx 2 seconds to get to the other end!

Yes the 2in sprinkler will make a very large difference over a 1in one I would recomend you make a piston valve but you are not willing to do that. A 1.5in sprinkler will work fine and wouldnt get much less power than a 2in sprikler.
I guess you could also use a 1.25in sprikler but you wouldnt get as much power.
A 1in sprinkler on that size chamber would constrict flow tremendously.

yea i know there will be a large diference, it will actually cost more to have a 1.5" rather than a 2" because of pvc fittings i would need to bring it back down to size.

dongfang wrote:Naaah not quite. Area grows by the square of the diameter. Exponential growth is faster.

Right you are, my bad

dongfang wrote:
Carlman I'm afraid you can't get a golf ball into a 40 mm pipe. The ball is 42.67 or something like that. But build the gun anyway; 40mm is a good size, not too big (expensive, lots of pumping etc) and not too small (boring).

40mm PVC Pressure Rated pipe has an I.D of about 43.5mm. You're referring to the nominal diameter, which in some countries(UK I think) is the real I.D so I think that's where you are confused.


@Carlman

No idea, never used it for damage shots, except for the watermelon, after it blew the wastermelon up, it stopped dead, didn't hit my back stop about a foot or two away.

Hi McCrowley,

OK, if the pipe is large enough then.......

In here, an X mm pipe is ... taddaaaaaaa --- X mm in the outside. No more no less.

Regards
Soren

good for you dongfang

no seriously what was the point of that?

different places have different ways of measuring pipe.