A Few Ideas...

[Labtecpower]

I have drawn up a plan.



How does this look to you?

[Technician1002]

Too much gas can compress into the yellow fitting on the bottom which will remove much of the avaliable energy that should go into the barrel. Other than that, I like it.

I would have lengthened it for a longer stroke so the piston speed could have been higher. One design on paper I was playing with had a 4 inch chamber with a 10 foot length. It would be powered by air from a small pumpkin cannon. The last 1/2 foot of travel will provide a high compression pressure into a golf ball barrel. In theory the piston could be moved with a 200 PSI source and provide over 600F air onto the golf ball due to compression heating and > 20 Bar pressure. This would provide the light gas for a local SOS above normal.

[shiny455]

Alright im confused now you's aren't making the hybrid inside a hybrid are you. If you are making this you have to explain how it works. What technician1002 was saying makes it sound like a two stage kind of pump not a gun

[Crna Legija]

you ignite the mix behind the piston, that makes the piston move forward fast
which makes the air fuel mix in front heat up until it get hot enough to explode. pushes the round down the barrel. i think thats it.

[shiny455]

oh ok so you use a hybrid to create a diesel effect yeah?

[jackssmirkingrevenge]

Balanced piston that avoids the need for a detent, I like it!

My initial though was that the "autoignition" hybrid mix would start at atmospheric pressure but this is even better!

The idea definitely has potential, though again, it's a needless complication if you have the option of filling more than 1 atm of propane.

[Labtecpower]

I don't completely understand what you're saying. Would the hybridhybrid be a needless complication when you're able to get very high mixes? in this design, you could put 30x mix on both sides, getting a very high pressure diesel effect on the other side.

[saefroch]

Have you done any calculations to support the assertion that you can reach appropriate autoignition temperatures?

[Technician1002]

Propane has high ignition temperatures. Oil is much lower and can be used as a starter. A oil wet scrap pf paper could start it.

[POLAND_SPUD]

I hate to be that guy who says something that questions the practicality of the whole idea but...
Can't you just build a high mix hybrid ? like 20-30X or so ?

[jackssmirkingrevenge]

I don't completely understand what you're saying. Would the hybridhybrid be a needless complication when you're able to get very high mixes? in this design, you could put 30x mix on both sides, getting a very high pressure diesel effect on the other side.

The hybridhybrid has the potential to reach ridiculously high mixes, but effective chamber volume is reducing proportionally at the same time, and you have no idea at what mix it will actually ignite - it can be calculated with some effort.

The point is, imagine a 2 inch diameter 10 inch long chamber.

You put a thin piston in the middle and make a hybridhybrid, with 20x on both sides.

When the piston compresses to 3,9 cubic inches, you'll get an 80x mix - but will this give more power (and if so, enough of a worthwhile increase) over simply using a 20x 31,4 cubic inch chamber?

It's a complex thermodynamic calculation, I suppose one just needs to build it, in such a way it can be tested with and without the piston fitted.

[Labtecpower]

I think it will give an increase in power anyway. When the piston is slammed forward, it may give a 4 times smaller chamber, but also a 4 times higher mix with significantly more force, and just as much gasses as in a 20 x mix. Wouldn't the combustion heating combined with shock heating increase the gas volume, and lowering the gasses SOS even more than in a 20 x mix?

And, if it doesn't work, just take out the piston, and put a 30x mix into it

[jackssmirkingrevenge]

And, if it doesn't work, just take out the piston, and put a 30x mix into it

That was the gist of the last sentence

[shiny455]

i am probably wrong but if you had two lets say 20x chambers after the first one ignites and pushes the piston forward wouldn't the second ignition put at least half of its energy into pushing the piston backwards rather than the projectile out of the barrel as the area behind the piston only has whatever pressure the ignition of the 20x gives and the detent in the barrel would have to be at least more than that or the projectile will leave the barrel before the second mixture diesels. what i just said may be redundant depending what JSR meant by saying

Balanced piston that avoids the need for a detent, I like it!

.
and now that i think about it this gun it should give the ultimate power possible from a hybrid 'the ignition point of propane' this is true right?

[jackssmirkingrevenge]

wouldn't the second ignition put at least half of its energy into pushing the piston backwards rather than the projectile out of the barrel as the area behind the piston only has whatever pressure the ignition of the 20x gives and the detent in the barrel would have to be at least more than that or the projectile will leave the barrel before the second mixture diesels

The man makes a good point, a heavy piston is a must.