The barrel is what slides rather than a bolt, and when the breach is open, the checkvalve opens at the butt to allow 5 second exhausting of the chamber before reloading.
In the video, I did not switch on the fan before injection, so that would have been a misfire!
Re: New member... my baby, Big Red
Posted: Sat Apr 25, 2020 6:14 am
by mark.f
What's the construction? Using pure oxygen + fuel in plastic piping isn't a great idea. Maybe that's why you didn't actually fire the thing in the video.
Re: New member... my baby, Big Red
Posted: Sat Apr 25, 2020 10:46 am
by KannonKing
"pure oxygen" and fuel? Maybe you noticed the vacuum pump hidden in the battery box that evacuates the chamber before filling it with "pure oxygen and fuel".
Re: New member... my baby, Big Red
Posted: Sat Apr 25, 2020 12:58 pm
by Moonbogg
It looks great. I was also wondering about the oxygen use regarding its safety in a PVC cannon.
Re: New member... my baby, Big Red
Posted: Sat Apr 25, 2020 2:58 pm
by KannonKing
I have not had any problems shooting with additional oxygen. I have completed calibration using propane and mapp, but have not had enough shooting time to test with oxygen.
With plain fuel air mix I have achieved about 700 joules muzzle energy (only a 5' bsrrel, so chamber/barrel ratio is high), but some testing with an 8-foot barrel extension showed promising results).
I've cooked rounds with added oxygen (about 1/20th pressure relative to fuel) which I calculated would increase O2 content in chamber to about 22%. I fired about 20 rounds using remote trigger (2 boards and a string, pull string, board drops on igniter). I did not have the Chrony that day, but I noted a sharper rapport and a significant increase in muzzle flash.
Due to my current residence, I have nowhere to safely fire this unit (at least with this barrel and golf balls) so any further testing is off. Sadly golf balls are the least safe ammo due to the infinitely variable angles of return. And with over 800 yards range, I ain't taking that chance here.
"pure oxygen" and fuel? Maybe you noticed the vacuum pump hidden in the battery box that evacuates the chamber before filling it with "pure oxygen and fuel".
I didn't notice much of anything since you just posted a video.
You sound pretty smart, we just tend to get nervous when people post pictures of plastic guns with oxygen tanks attached. I'm sure you're limiting it to a relatively tame amount of "enrichment" but there are tons of people on the internet who don't.
Overall good execution, and shame you can't get out to test it some more.
"pure oxygen" and fuel? Maybe you noticed the vacuum pump hidden in the battery box that evacuates the chamber before filling it with "pure oxygen and fuel".
If you're pulling a vacuum before injection, what *else* would you be using?
Re: New member... my baby, Big Red
Posted: Mon Apr 27, 2020 1:14 pm
by KannonKing
My apologies, I was being a little facetious, I would never consider detonating such a fuel/oxidizer mix. I thought the "miniature vacuum pump" was my obvious tell... I'll be sticking to a high nitrogen content with this device thank you very much. And I'll cancel the snark until you get to know me.
I'm a graduate of the University of Burnt Latke, and Imperial College, so my credentials are pretty good.
This is pretty much exactly what I am seeing with the above described fueling. 588 fps was my fastest clock round
It's like to think that with the barrel extension, I could get up here...
To be clear, this is not a hybrid cannon, just using HGDT with it's most appropriate settings.
Re: New member... my baby, Big Red
Posted: Mon Apr 27, 2020 4:11 pm
by Moonbogg
Welcome to the forum! I saw Burnt Latke and knew you were a true spudman. We are united by the potato starch in our blood and propane in our lungs. Together we shall breathe fire and cough out tater tots.
Pickle me grand mother.
"big belly laugh".
Dunno about ya tech thing variables golf balls.
Yeah 750 mtr range...
I av golfer, smak em 240 mtrs.
When I get onto em , Its "Anzac" on the tee.
One minute of silence, that is.... Gahahaha.
I'd Rekon I give big red, prob 5 mins of silence after seeing it in action.
It looks promising, not many combustion repeaters out there.
Re: New member... my baby, Big Red
Posted: Thu Jun 04, 2020 10:46 pm
by jimmy101
"Burnt Latke", ah, those were the Days...
Don't need a vacuum pump to run pure O2. Just flush the chamber with the O2 before adding fuel, not all that hard really, but might get expensive. But pure O2 is up around 5x the power of propane+air.
None the less, it looks like you know what you are doing and the "launcher" looks sick.
Pickle me grand mother.
"big belly laugh".
Dunno about ya tech thing variables golf balls.
Yeah 750 mtr range...
I av golfer, smak em 240 mtrs.
When I get onto em , Its "Anzac" on the tee.
One minute of silence, that is.... Gahahaha.
I'd Rekon I give big red, prob 5 mins of silence after seeing it in action.
One of the nice things about using a extendable SDR-21 barrel and golf balls, since the barrel droops somewhat under its own weight, the ball actually starts to roll along the top of the barrel causing backspin on the ball and a perfect "drive trajectory" with that beautiful arched rise....and then it's gone, never to be seen again.
And when you shoot it straight up, it takes the ball around 25 seconds to return to Earth... Count that out!
Sadly golf balls are the least safe ammo due to the infinitely variable angles of return. And with over 800 yards range, I ain't taking that chance here.
