That is the idea, because golf balls have well known aerodynamic principles my thought was to do just that, but in real life the pneumatic cylinder has too much slop even when used in a double valve setup, so in the future I will be moving to a threaded rod elevation, possibly using the cilinder to ...

Thanks! Still working on testing

Built this one awhile ago, sch 80 PVC, 150psi shoots a golf ball at 1000fps (measured) Uses a 35in pneumatic cylinder for elevation, and an 8in pneumatic cylinder to actuate the rear valve Coaxial with a 10ft 2in diameter sch80 pvc barrel and a 4ft by 4in (I think?) chamber 4700ft hypothetical range...

Thats a shame. I may have a new summer obsession now...

yes you could split it up

FYI for all the barrel is going to have to be something like 8-10m long (26-32 ft) long for the acceleration i was talking about with close to liner progression until then (it has decreasing returns after that)

Highlighted areas with combustion
This is of course uper rough

Edit: finished some preliminary math from some papers I read and found out that we are talking about exit velocities hovering around mach 10 (3,402.9m/s)

This is the latest design based on papers and my own influence and results (i will try the non stabilised one next because right right the projectile is in there for something like .00789 seconds with a 8ft tube (w/o acceleration due to combustion) Edit: With open air flight (it too was an influence...

ramses wrote:As I remember, Autodesk CFD doesn't simulate compressible fluids.

CFD can do compressible fluids and supersonic flow along with tones of other stuff however it cannot do 2 essential things
Temperature increase due to gas compression
Burning/Ignited gas or fluid

Well I did a little digging and Autodesk CDF cannot simulate the shock wave in sutch a small space as the tube, so the shock wave would impart enough energy on the gas to ignite it, at least according to what I read. I will have to brush up on my, well everything. Edit: here is one of the papers tha...

I would love to see this built and played with I think it could be a new era for spud guns (that of the ridiculously expensive projectiles shot at extremely high speeds just because you can) Edit: After duble checking my math you would need pressures in the 190,000psi to get the oxygen/hydrogen gas ...

The projectiles are 2in in diameter and by blow back i mean it would ignite the gas in-front of it blowing the projectile back into the gun

This is what happens when it moves too fast (it ignites the gas in front of it) blow back seems like it would be bad...

It has charastics of both but more similar to scramjet

Edit: It looks like it ill flw well with the fins

But it will make an epic shockwave

idk i will do some free flow sims today