"SC3650" In-Line Piston Hybrid Cannon

Harness the power of precision mixtures of pressurized flammable vapor. Safety first! These are advanced potato guns - not for the beginner.
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Moonbogg
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Wed May 22, 2019 8:05 pm

This is the SC3650 In-Line Piston Hybrid Cannon. The entire build log from beginning to end is in the link below. I'll just show the cannon here and keep it simple.

http://www.spudfiles.com/hybrid-cannons/topic26921.html

[youtube][/youtube]
[youtube][/youtube]

EDIT - June 5th, 2019: Fueling improvements increased performance.

first 2 shots are full 12oz soda cans
3rd shot is a potato
4th shot is a golf ball
[youtube][/youtube]

Here's the money shot!
[youtube][/youtube]
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Last edited by Moonbogg on Thu Jun 06, 2019 12:43 am, edited 2 times in total.
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jackssmirkingrevenge
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Thu May 23, 2019 4:39 am

Glad it finally paid off :D are you sure it's a mixing issue and not a air:fuel ratio issue?
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Moonbogg
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Thu May 23, 2019 9:46 am

jackssmirkingrevenge wrote:Glad it finally paid off :D are you sure it's a mixing issue and not a air:fuel ratio issue?

I'm not sure, but I am leaning toward fuel/air mixture. I was pretty careful about measuring volume, although I'm not 100% sure what the volume is inside my meter pipe. I took into account the ID of the pipe and the length and just gave it another 2 inches to estimate the volume for the fittings on it, so it's close, but not perfect.
It could be a lack of oxygen on some of the shots for not fully venting the chamber. I'll need more time with it on the range, but I'm for sure going to do something to help the mixing.

Also, on the first shot of the "hybrid shots" video, listen to that smooth breech clunk softly as it closes. I swear, the best thing about my last two cannons is adhesive backed UHMWPE, lol. I absolutely love the hell out of that stuff. It makes amazing makeshift bushings and protective surfaces. That's what's in the ID of the barrel guides and it works amazing. One installation of that stuff has worked perfect for 10 years on my last cannon.
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jackssmirkingrevenge
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Tue May 28, 2019 6:38 am

Moonbogg wrote:
jackssmirkingrevenge wrote:I took into account the ID of the pipe and the length and just gave it another 2 inches to estimate the volume for the fittings on it, so it's close, but not perfect.
If you underestimated the volume of the meter it would make it rich. One way to get an accurate reading would be to fill it with water taking care not to leave any air gaps and measure the volume used, I had done it for my shock pump.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Tue May 28, 2019 12:48 pm

You know what, I think you might be onto something with this issue. The reason is because I am using the same meter pipe that I use for my venom cannon. That Canon has a chamber volume about three times as large as this new cannon has. So it would be much less sensitive to inaccuracies in meter pipe volume. However this new Cannon would be much more sensitive to inaccuracies in meter volume since the volume of that chamber is so much smaller. So I will definitely be measuring the meter pipe with water to get it accurate. Thanks for pressing the issue because my brain auto-ignored it since that pipe was working well for a decade, just with a different and much larger cannon!
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