4L Propane Inline Cannon

[MDSpudderButter]

Hello all! New member here but have been lurking for a few years. Just finished up my latest build on a metered propane combustion. Specs are as follows:

4 foot 2" diameter barrel

3,990 mL

40 mL meter pipe

80mm chamber fan

2" quick vent ball valve

"400kV" ignition module running at 6V input

9V running the chamber fan.

No reinventing the wheel on this one but I had a blast building it and it shoots well thus far! Wish I would have taken more pictures during the building process.

[mark.f]

Nice, well executed combustion launcher! I myself am slightly partial to them.

I'd be curious for some more details on the electronics, along with more closeups of the chamber. Banjo couplings are a nice touch. Can't tell if that's rubber under the hose clamps or the sling.

Good job!

[MDSpudderButter]

Thanks mark! Appreciate the comments. I have a 1" sprinkler valve pneumatic as well but hated that I was married to the compressor so the portability of propane was a huge draw for me.

The heart of the electronics is the 400kV high voltage generator I got for around $9 on amazon. That is powered by (4) AA batteries wired in series to give roughly 6v on the input side. This has a master toggle safety then a momentary push button for firing. The fan is just running off of a single 9V. It's funny because I was curious if I could run 2 9V batteries in series for the PC fan and you were the only one who vaguely mentioned it years ago so I would love some input on that.

That is rubber electrical splicing tape under the hose clamps. I have found so many uses for this stuff since I used it wiring a 12v power supply into my motorcycle this summer. Excellent stuff and very forgiving. The sling is from an old airsoft sniper with a broken bolt.

I am currently working on reworking the camlocks for a pass through 1.5" barrel and also use it as a burst disc coupling for a golf ball barrel. I will continue to update this post with pictures as I keep working.

[mark.f]

The fan is just running off of a single 9V. It's funny because I was curious if I could run 2 9V batteries in series for the PC fan and you were the only one who vaguely mentioned it years ago so I would love some input on that.

Indeed, I have a page on it. https://www.spudstalker.ninja/home/spud ... stion/mix/

The simple version: two 9V in series works fine. Add a 12v regulator in series with the fan to tame it down to 12v.

[MDSpudderButter]

Thanks Mark. I figured a linear 7812 would work but was hoping I could just run strait 18V in short bursts. Attached are some more detailed shots of the chamber. I give the cleanliness credit to the new to me Oatey Fusion. I was a little apprehensive about an all in one but the spec sheet was identical to regular medium cement so I figured I would give it a shot. I will post some more pictures of the pass-through barrel once I cut the double bevel on it tomorrow. If any one has any specific questions feel free to ask! I am hoping this build will encourage others to continue spudding as well.

[MDSpudderButter]

Got to do a little more work on the cannon today. Pictures show the fittings and double beveled pass through barrel. The PVC fittings only took 15 minutes to sand out but the black camlock took over an hour and a half. I also switched the camlock on the chamber to come through a SCH80 close nipple which allows the barrel to pass through good and snug. Working on a latke style trigger as well.

Does anyone have inputs on a 12V source like this...https://www.amazon.com/HitLights-Rechar ... pack&psc=1

My thoughts are to run the 12V to the fan and use the 5V USB port as the input for the HV generator. At about $10 each time to replace batteries, I am tempted to go this route especially with the fan getting closer to its correct voltage.

[MDSpudderButter]

Had a day off Tuesday and it was 70 degrees here so it was the perfect day to give the new launcher a shakedown. Attached are some pictures of damage that cannon did from varies ranges. Also embedded is a youtube video of a few shots. Just now learning to use the go pro studio so I apologize if the slo mo seems over the top. All in all the gun shot great and had no issues tearing through all sorts of targets.

[youtube][/youtube]

In addition I went ahead and ordered a used 0.7A (8.4W) 80 x 80 x25mm PC fan from ebay as well as a new small project enclosure and the Hitlights 12V rechargable pack shown above. Once I assemble these I will review this setup for anyone looking to go this route in the future. I have located a local plumbing supplier that carries both 1.5" SDR 21 as well as 2" SCH80 PVC so a golf ball barrel is in the works.

[200BAR]

Great build and damage pics/vid.
Thanks for sharing.

[jackssmirkingrevenge]

That looks like a fun day out, great job! Was this just with spuds or did you use something more solid as a projectile?

[MDSpudderButter]

Believe it or not this was just spuds. I thought the potato would explode instead of splitting the 2 x 4 but it hammered right through. The plywood wire spool acted like a taught piece of paper and they punched right through as well.

I have attached a few pictures of the updated electronics with the switches relocated to the edges and the battery pack velcroed on top. So far a quick bench test shows that the fan is spinning much faster and the spark sounds as strong as ever. My only worry is that the high kV module will draw too much current but it shouldn't matter in short bursts.

[jackssmirkingrevenge]

Believe it or not this was just spuds.

Easy to believe on this forum, velocity is king even if your projectile is softer than your target.