Combustion Light Gas Gun
Currently a single stage combustion light gas gun, plan for a duel stage version in the future

The current version uses oxy propane and has a bore of 1 inch
I saw a video a long time ago of a hyper velocity CLGG at Texas A&M for hyper velocity impact testing and a similar one at NASA and was inspired to make a simplified version of my own and test different projectiles and chamber designs for the highest speed I could achieve.
Texas A&M (https://www.youtube.com/watch?v=FtbLTBGH62M)
We would set up slow motion cameras and calculate the velocity of the projectile from the frame rate and size of the projectile or know distance

Distance testing

Mach Diamonds 1

Mach Diamonds 2
One of the most impressive and exciting parts of this project for me was seeing mach diamonds (or shock diamonds), which suggests super sonic gas flow (the gas exiting the barrel is at a higher pressure (seen by how the stream expands immediately after the exit) but the expansion can overshoot the ambient pressure and cause a series of compressions (shocks) and expansions (fans). As this happens a number of times you can see the set of diamonds). This isn't helpful in any way to the system in fact it is harmful in terms of efficiency, projectile stability, and my ears. I mostly thought this was cool because of my interest in rocketry and jet engines and not with progressing the project. Also I was interested in how fast the gas was going.


Mach diamonds seen in an exhaust plume from the swiss propulsion labratory

Mach diamonds diagram