Clide...That would be great.
I'm a Mac guy so ggdt is off limits to me.
The C:B ratio for a combustion cannon has been beat to death pretty good but I don't hear much discussion on piston ratios.
The other thing not talked about is how far the valve really needs to open....
and....
Fluid dynamics around the barrel entrance.
There was an article I read about deep well drillers and their discovery with the flow of fluid through pipes.
One of the worst flows possible available is into any square cut pipe....the end of a pipe exactly like that in most every spudgun.
They had pictures of vortexes and back eddies that form during high flow periods and discussed how much flow actually chokes the pipe off...and it is really significant! I would think especially with piston valves.
The fix is really easy which is like a venturi insert into the pipe....which actually makes the pipe inside diameter smaller but because the insert direct the flow...it stops the back eddies and allows much more flow.
Basically I am saying most cannons could benefit from installing a simple insert.
We purchased carbide nozzle inserts used for deep well oil drilling...only we used the nozzles for another application. In one the boxes we ordered was some literature about flow into pipes. I think it was Smith International or Smit International, a company in Texas that makes all sorts of drilling applied tools and such. One thing they were offering was these weld on inserts for pipe ends to increase flow in a pipe.
So...after writing this...it occurs to me the the chamber sealing valve has an advantage over say a coaxial.
Sure like to view others thoughts on piston ratios.