SpudFiles

Over the last two days I cut the restrictive valve off the front and welded in a 2" coupling and added a 2" union to open up the air way.

I relocated the blasting cap fitting and the fuel/air input and gauge location to the sides of the cylinder and test fired it tonight at 3X mix.

Using aluminum flashing for my burst disk, it cut the center of the disk out cleanly and I also recorded the shot on video which I put on youtube for you guys to see.

The best part was afterwards all the neighbors walked out into the street looking towards my house trying to see where the explosion came from! lmao One of them even yelled down to see if everyone was alright... I was also shocked at how loud it was. It was nowhere near what I was expecting, it was an amazing feeling when it fired on the first try and was it obviously has plenty of power to recoil the cylinder like it was nothing.

Its an awesome feeling






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I have been inactive for a long time but I recently received a halon fire suppression cylinder from my work place and noticed that it would make an awesome big bore hybrid cannon.



These are my measurements. Do you think it will work?

Cylinder 11" Diameter x 32" long

3042 Cubic Inches Chamber Volume

Meter Pipe Volume: 36 Cubic Inches

122 Cubic Inches Fuel Volume in chamber

Propane Supply: 50 PSI

Meter Pipe 2" x 12" is around 37 Cubic Inches in volume.

I will have to inject this mixture twice, to have a 1x mixture correct? I will have to inject it 4 times and pressurize the bottle to 15 PSI with a compressor to achieve a 2x mixture?

You've been away...
(lol at the outdated Ron Paul sig)


I think the first question to ask would be: is there a rating visible on the tank anywhere? With a few minutes research it seems this type of cylinder should be rated to at least 600 psi; it should be fine for anything under 5x or so, assuming you can verify this.

Too lazy to spoonfeed fueling math right now, sorry, but I'd consider using a manometeric meter on a chamber this size- Just get a very accurate(+/- 0.1psi) gauge, and add fuel directly to the sealed combustion chamber. Isolate the gauge when firing.

Also, what are you planning on for the valve? That's a lot of gas to move out.

11" dia? Did I read that right? Can you find out what its made of? Is it designed for pressure use? With that large of a diameter there will be a whole lot of stress on the chamber wall. Make sure first...

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Since this is a Halon fire extinguisher, just do a little searching. Google is your friend! The vapor pressure of the particular Halon gas used in Halon fire extinguishers (Bromotriflouromethane) is about 200 PSI at 20 degrees C. I would say the tank is good up to about 300 tops. I would hydro test it if at all possible just to be safe.

Mr.Tallahassee wrote:Since this is a Halon fire extinguisher, just do a little searching. Google is your friend! The vapor pressure of the particular Halon gas used in Halon fire extinguishers (Bromotriflouromethane) is about 200 PSI at 20 degrees C. I would say the tank is good up to about 300 tops. I would hydro test it if at all possible just to be safe.

I got a halon fire extinguisher for this purpose, but it was only rated to about 200 psi also. It now resides under the passenger seat of my car.

Thanks for the replys guys.

As for the rating of the cylinder.. I can't be sure of that. Or the wall thickness. I can tell you that this 32" tall cylinder weights 145lbs empty.

This type of halon cylinder stays pressurized at 360PSI for years and years using dry nitrogen to push the halon out of the bottle just like a big spray paint can.

My plan for firing this thing is to use a remote control car steering servo and receiver inside a project box to flip a toggle switch that will send voltage from a 1.3AH 12 volt battery across the powder charge of a GCA (Gas Cartridge Actuator) that will ignite the fuel/air mixture.

I should be at a safe distance behind something big and heavy when firing.

I have already constructed the meter pipe, there are somethings I would like to refine before the first shot. But I do like the direct injection method with a highly accurate digital gauge...

Here are some pictures of the setup so far.

Umm, you are going to need a bigger outlet from the tank. The flow restriction on that union and pipe will not flow enough volume to make use of over 90% of the chamber volume. That will flow a lot like poping the hose off a compressor. It will blow for several 10's of seconds. Only the first 0.030 of the flow or less will propel the projectile. A chamber 1/20th the size will have about the same performance on that barrel setup.

Yep I figured that also and I knew i would need a barrel a mile long to get the maximum from the chamber.

I also thought about something as I was writing the post earlier about the big spray paint can part.. There is actually a tube that extends from the opening where the barrel would go - alll the way to the bottom/back of the chamber. It's just like the straw in the spray paint can.

That tube will cause all kinds of problems.. from the mixing of the fuel/air and possibly bursting the burst disk before the mixture even ignites and creates any decent amount of pressure in the chamber..

So I relocated the detonator port to the side of the chamber - which I discovered is about 1/4" thick! I welded the port, and welded a 3/4" x 1/4" bushing in its original position that I will use for another gauge.

Going by what you have said and how the whole setup works when I fire it. I may cut the valve completely off the top/front and weld it up to the bottom/back of the chamber and weld in a 2" union up front for the barrel.. That should flow very well.

Hate to double post guys but I just wanted to let you know that I updated the first post with new pictures and a video of the first test shot at 3X!

:O wow! Nice job!

Very nice! I suddenly feel very inadequate with my measly 130 cubic inch hybrid

Wow, that thing is huge. Really cool stuff.

this is going to be good, real good!

"it works"

spoken like a true "boom" making scientist

surprised it didn't loop around the tree, nicely done