Me and Larda were tossing around an idea a while ago using this idea, minus the heating effect. Although it was far too long ago for me to remember the specifics, it was essentially a solid fueled hybrid (the fuel being a flammable powder like flour or icing sugar, possibly mixed with volatile liquid hydrocarbons for ease of ignition, depending on initial results). The fuel would be held in the main chamber and a blast of high pressure oxygen (>2kpsi) dumped through it from a secondary chamber, distributing and igniting the fuel simultaneously. That was the theory at least. The amount of difficult and expensive testing required to make it work effectively and safely meant that neither of us got around to it.
It did, however, carry the potential to generate rather high pressures while doing away completely with the fuel metering system (very expensive on high mix hybrids). While not capable of the extreme velocities CLGGs are, it would certainly be worth a try. The major concern in such a system would be the valve to dump the oxygen; almost any conceivable seal would be destroyed either by chemical interaction with the O<sub>2</sub>, or the post-ignition conditions in the propellant gas. A BP actuated burst disk would likely be the most affordable option for initial testing (for certain totally unrealistic values of "affordable"
![Rolling Eyes :roll:](./images/smilies/icon_rolleyes.png)
).
As to the construction of what was proposed initially: a moving piston to compress the gas rapidly enough would be a necessity. Modeling how the piston moves during the gun's operation is a nasty job indeed, and an excessively fast or rebounding piston can severely stress or completely destroy the launcher. This not to mention how the piston's seals would fare. The application of this design to anything other than small plinkers is getting into some very difficult design territory, which probably isn't tremendously beneficial. However, as always, if you've got the money and inclination to try it anyway, I'd be happy to help with the design.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.