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First Timer w/ a metering system??

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: SpudBlaster15 » Fri Mar 07, 2008 1:36 pm

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Unread postAuthor: DYI » Fri Mar 07, 2008 1:48 pm

Yeah, I know.

I don't really think that it harmed anything very much though, did it?
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Unread postAuthor: SpudBlaster15 » Fri Mar 07, 2008 2:04 pm

It didn't really harm anything, but significant figures can really come back to bite you in the ass should you ever desire to take a high school science course.

I usually stick to Pressure = ChamberVolume*0.042/MeterVolume*AtmosphericPressure for regular combustion guns, because in my experience, potatoes form rather terrible seals, and the incoming propane volume will force 4.2% of the chamber's original atmosphere past it. Calculating what the original chamber volume is (100-Fuel%)% of is useful for hybrid launchers though. Keep in mind however, that to be as close to accurate as possible (well, assuming no mixing of the residual propane in the meter and the chamber gases), the rise in chamber pressure should be calculated, and that pressure should be added to the propane meter pressure to compensate for the increase in residual volume (unless of course you use my original hybrid design, which I don't use any more on account of "absurdly large fuel meter volume" syndrome affecting my mix accuracy at higher pressures).
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Unread postAuthor: Spitfire » Sat Mar 08, 2008 4:20 pm

BigGrib wrote:Math Hurt Head..............................................


A unfortunate truth. But one cant live without it.
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Unread postAuthor: q » Wed Mar 12, 2008 7:47 am

crap...

well i just inspected my wye fitting and it si in fact a dwv fitting. With a combustion chamber of this size should I be worried about this and scrap the project or what????? :oops:
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