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Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: DYI » Fri Apr 11, 2008 10:42 am

If you measure the volume of an unprotected steel chamber with water, it will cause accelerated rusting if it's exposed to air again (which it will be on a regular basis in this case). If the steel is galvanised, all you have to worry about are the threads.

For a 500mL chamber at 4x, you will need a total of (500 x 4) 2000mL of air.

To find what volume 2000mL is 95.98% of, divide by 95.98, and multiply the quotient by 100, which gives you ~2084mL. That means you need 84 mL of propane going in to the chamber.
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Unread postAuthor: Modderxtrordanare » Fri Apr 11, 2008 1:39 pm

So I'm getting to think that I'm be better off setting it up as a genII (if that's something people are still doing) with a 2000mL filling tank and inject the 84mL of propane into said tank. Followed by displacing it all with water through a line/check valve, that should force the 2000mL of air + the 84mL propane into the 500mL chamber ready for a 4x shot, correct?

It's galvanized steel by the way, and I only did it once, I should be fine right? I'll make sure to use something else for any more measuring.
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Unread postAuthor: DYI » Fri Apr 11, 2008 3:44 pm

The thing with Gen II systems is that they really aren't infinitely adjustable in terms of mix, unless you can pull a vacuum on the firing chamber, or fill it with an inert gas before fuel injection.

And you don't even understand the principles behind this, which is a good indication that you haven't done enough research. If you filled a 2000mL mixing tank with the matching amount of propane, and displaced all of it into the chamber, you would have 2500 mL of air in the chamber, not 2000. And if you did your idea properly, you'd still have only one shot before you had to refill the tank, defeating what small advantage that Gen II has over all of the better designs. Gen II isn't even a meter design for that matter, do you not realise that you'd have to build the same meter no matter what design you use (except mine, which is horribly expensive, and of little use for such low mixes).

Do you have any idea how this works?
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Unread postAuthor: pat123 » Fri Apr 11, 2008 3:58 pm

Yeah the threaded sch 40 steel is probably the easiest to work with. check out HCMP in my sig for fueling.

edit: just make a normal meter attached to your propane tank or whatever you are using. fill the meter to the pressure that will make the amount in the chamber correct.
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