Silencing

[mmezz]

Hi,
I have finally built my dream spud cannon but it is WAY too loud! However, it does fire at least 350 yds.
Here are the specs:
-14 inch barrel
-metered propane injection (i'm currently using 37psi of propane according to the online SpudTool) http://advancedspuds.com/propane.htm
-bbq starter ignition (stun guns aren't legal in new york)
-sweet chamber fan
-4 foot 2.5" tennis ball barrel (the tennis balls fit extremely tight so I use liquid soap on them to reduce friction)

The problem with it being too loud is that I have neighbors that hate loud noise I have previously seen 2 pictures of people's tennis ball cannons where they use only a 2 foot barrel with propane and they claim that it's silent.
Should I cut my barrel down to that length to cut the noise down?? If so, will it also reduce my distance?
Or should I use less propane to cut the noise down?
Does using liquid soap on the tennis balls create the loud noise?
OR is there anything else at all that will limit the sound?

OK, any help at all with this would be greatly appreciated!
thankx

[CS]

Muzzle break to allow that high pressure spike to realese over a period of time rather then all at once when the tightly fitting TB exits the barrel. Or you always can go with a supressor. (everyone dont flip shit since we know why it is being used) Lengthing the barrel is always a option, but not really for existing cannons.

[pyrogeek]

Adding a silencer would be good. Changing the amount of propane won't really help, since you need the correct mix otherwise it won't work at all or the gun wont fire very easilly, especially with a grill ignitor. Maybe you should look into an ignition using a disposable camera or flyback, then mess with changing the fuel:air mix.
I don't know for sure, but I have a feeling that the tight fitting tennis balls are contributing. Would it be possible to find some old, worn down tennis balls to test and see if they would be quietter?

[SpudStuff]

I hade the exact same problem. i solved it by drilling 1/8" hiles in the barrel. i drilled them in the end of the barrel to vent it. it is still loud but it helps. the other option is to get a 2.5 inch tee and drill a 2.5 inch hole exactly where the ball would pass through. i used that on a mini and it is amaing the differance.

It is like 106 degreese today. it is so FUCKING HOT

[Dom]

Bringing up this post..

So if I drill holes in the end of the barrel it should make it quieter? Will this affect performance?

[FiveseveN]

It depends on the size of the holes and where you drill them. Holes mean you have less acceleration, but the same amount of friction (even more if you don't clean up the holes).
Having huge holes starting from the middle of the barrel will cut your performance down quite a bit.
On the other hand, tiny holes just near the muzzle won't make much difference in performance or loudness, unless muzzle velocity is transonic.

You have a couple of options:
- a bunch of small holes at the very end of the barrel (no more than 20% of total barrel length). The total area of your holes should be equal to your caliber or slightly larger. Slightly flaring the last inch or so might also help but be very careful not to offset the axis.
- one of various suppressor designs, such as a reflex suppressor. Here's how I made mine:



A is the outer barrel (only relevant to my gun; you can ignore this)
B is the barrel
C is the expansion chamber, made by combining two upper halves of PET bottles. They slide onto the barrel and are held by friction (electric tape). It provides about half a litre of volume, which is quite enough in my case.
D is the muzzle brake. It consists of two holes (transverse to the barrel's axis) 4 cm from the muzzle. Their total area is around 1.7 times the caliber.

[LucyInTheSky]

Would adding a Tee with a hole drilled in the same size a the bore work like this?

[MisterSteve124]

why do people not like the loudness that is one of the best parts jeez

[Dom]

Maybe because I am near a military base, RCMP buildings, a small Cessna airports (so it's considered has violation of airspace)..

[djt]

that doesnt have anything to do with the noise...

but i can see why you wouldnt want it to be loud. if it was at night, you wanted to fire it in dead silence and you had neighbors that could get pissed off...then you definately woulndnt want it to be loud.

[Dom]

As for the RCMP, yes, it has a lot to do with noise. I live very near Sussex Drive in Ottawa, which is where our nice Prime Minister lives..

[MrCrowley]

LucyInTheSky - i heard that only stops muzzle flash not the noise,well not by much anyway.

[guitarfreak]

I would extend the barrel by a foot or so, just do what I did; Find a bit of pipe that fits snugly over the barrel, Ddrill holes through it and setscrew it to the end of the barrel. Works for me

[FiveseveN]

Yeah, that would act pretty much like the flanging I was talking about. Same idea as a silencer, but not as effective.
A muzzle brake is meant to increase accuracy and decrease recoil. It has nothing to do with noise, unless used in conjunction with some other system. I wouldn't trust drilling a hole in a tee like that. It's a critical place and if you're off by just a fraction of a milimeter, you're doing more harm than good.

[MrCrowley]

yeah i was thinking about that if the projectile deviated at the last slit second and you didnt cut a big enough hole in the tee it could clip it.