Here is my test, in this old video, but applied to an engine for an airplane. Very, very cool! I also like how your family seems willing to help with filming around devices that sound like they could explode at any moment :D Is it possible that the pressure generated inside the combustion chamber b...

Impressive performance and also a great look

You should try filling the cans with water, although not recommended indoors, in my experience the hydrostatic shock usually pops the cap off and makes a mess

Interesting concepts shown in the drawings. Which of these did you try? Which one worked best? I'm afraid it's all theoretical, I never actually prototyped any of these designs. I proposed something similar here . One possibility to organize the bbs and save air, is as follows. The holding oring on...

I made a prototype to test the viability of a 3mm HPA launcher for my sentry gun project, basically a tube fed detent type launcher. Sadly the rate of fire is far higher than I expected, in spite of the tight detent, I guess it's a result of tube as opposed to cloud type feeding, which puts the BBs ...

"Outer Diam" is the inner diameter of your chamber tube.

"Inner Diam" is the outer diameter of your barrel for a coaxial cannon.

If your design is not a coaxial, the "Inner Diam" should be zero.

Great to see you're still around and boooooooooooooo!!! to Aussie gun law

That was a great watch. this almost made me tumescent.

Found time to do some testing and an overview of the mechanism:

What does the chamber look like on these things? You should be able to tell from the photos but here is a simplified diagram of the internals: https://i.imgur.com/Iu04Ne8l.png Green arrow shows where the air is filled from, this is then closed off and another valve is opened at the red arrow to emp...

Most of the pneumatic projects on this forum use dump valves that essentially empty the chamber for every shot. Semi-automatics based on quick exhaust valves piloted by 3 way valves look something like this: https://i.imgur.com/JW8LrsI.gif A main chamber feeds a firing chamber, with the latter being...

Very nicely done! I really like the magazine lid.

A practical implementation of the valveless/popoff concept.

pdf here: https://archive.org/details/Caselman_Ai ... 9/mode/2up

another version: https://ia800207.us.archive.org/18/item ... prints.pdf

In my experience it amplifies the noise significantly for the shooter too.

In this specific case, 1.8K means 1.8 psi x 1000, it is 1800 psi, about 124 bar. Thanks for your answer. I confirm that is the case, a 1800 psi burst disk is typically one you will find on the exit side of a 850 psi regulator on a paintball bottle. A 3000 psi bottle will typically have a 5K disk, a...

Voila with a 1 meter barrel:



50cm barrel gives 319 m/s and 43J, 66cm gives 356 m/s and 53J

The blow forward bolt definitely works and is relatively easy to build:



What projectiles are you looking to fire though?