Thanks for the link JSR. I am starting to get used to the idea that all my "new and innovative" thoughts are old hat! I lolled at myself this morning.

Thank for the links to the ammo JSR. I didn't know it existed. As to my proposed idea (the drawing I did) I thought about the projectile needing fins especially because its short with a large diameter. That's why, in the drawing you see material inside at the back of the projectile in my drawing. I ...

You'd need rifling for them to fly straight though...

That must depend on design surely?

While we are on the topic of a projectile center of gravity, I have a design consideration. A hollow projectile driven by a pusher ( plus you can play add infinitum with the projectile dynamic) . Low mass, little drag vs large barrel diameter. Is there any merit to this? I was sure I had found the h...

No. The "tail" causes drag at the back, which allows the projectile to fly straight.

You would like to make the drag as little as possible though as it eats up velocity. Yet still have the projectile fly straight. Do you get my meaning!

Edit: sorry I didn't see this was an old thread. Here is a link to a 1960 patent of a compression ignition gun. Patent US2947221 - COMPRESSION IGNITION GUN - http://www.google.com/url?q=http://www.google.com/patents/US2947221&sa=U&ei=9yCIUe-0NrCp0AWbs4DgCQ&ved=0CBcQFjAA&usg=AFQjCNGUrf8w51TuPWHjs_kId...

"In any case, there is much to be said against conceiving of a theoretical system which you then couldn't afford to build." Prototyping can become a very costly venture. Better men than I have ruined themselves that way. All I was saying was I think I can get a lot closer to viability in design befo...

Touche! For therein lies the rub! :) A thousand dollars equates to just under nine thousand rand (our currency). There is an arsenal of really amazing weapons to be had for that price. It's not about that for me though. So what I am going to do rather than go the exploratory route is to get to know ...

"Just a thought about N 2 O, all it does it provide more oxygen to the mix." That is true when its in its liquid phase. In its gaseous phase it can decompose into N and O2 under heat and pressure. It is an exothermic reaction. I was sure you had picked that up. Sorry, perhaps I should have made that...

To JSR: " Fair enough but it's smacking of "free energy" to me..." That is exactly the thought that has been running through my mind this morning. With CO2 it can in reality be nothing more than a conversion of energy. I suppose what keeps catching me is that the heat/pressure relationship with CO2 ...

Well no matter what I build its going to cost money and time. More money than time because I will have to outsource everything. So in that case why not work on something that offers the spudding community something new to work with? It keeps things alive and interesting I would think. A 50x mix requ...

To JSR: "A simpler way to achieve it would be to charge the chamber with 20% oxygen, 4% propane and 76% CO2..." Very elegant! Yes that is! What you suggest would simplify the piston and chamber design, for sure. On the other hand it would probably be a pretty complex feed setup. An oxygen source and...

please excuse the double post. I thought that it may make more sense if I added a second pic of the design in the open position.

Both CO2 and N2O are sensitive to temperature. (N2O much more so). For instance CO2 at 70 degrees Fahrenheit has a pressure of 856 psi. At 300 degrees Fahrenheit the pressure is 5076 psi. At 600 degrees Fahrenheit the pressure is 13658 psi. N2O at 70 degrees Fahrenheit has a pressure of 762 psi. At ...

Is it? I don't think so. And if perchance it were truly to be dying then it would be a shame. On all of us. There are intrinsic, inherent flaws in the forum that can't be helped. Like for instance a noob going through thousands upon thousands messages trying to find info with regard to the specific ...