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HGDT 0.5 online

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: jimmy101 » Sat Jun 07, 2008 5:35 pm

D_Hall wrote:The beauty of pneumatics isn't so much in their performance, but in their clean and simple operation.

If you have access to a suitable compressor.

A combustion is probably simpler and cheaper to build and operate. With some pvc, glue, couple screws and a $4 long handled piezo "fire place lighter" you've got everything you need to make a functioning gun. Add another $10 and you've got a chamber fan and highly accurate metering system (and you've pretty well max'd out the performance of a standard combustion gun).
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Unread postAuthor: Lentamentalisk » Sat Jun 07, 2008 5:40 pm

A ten dollar union and a crappy bike pump doubles your power too... but back on topic ==> HGDT
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Unread postAuthor: ramses » Tue Jun 24, 2008 2:06 pm

I don't know if this has been brought up already or not, but at 1x it is telling me the pressure rise for propane should be .59psi, and for MAPP, it should be .29psi. Doesn't MAPP have a higher ratio than propane? It also assumes that the fuel displaces air at 1x. that is not necessarily a bad thing, but something worth mentioning. i don't know how the messed up pressures will effect the accuracy of the calculator, but whatever.
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Unread postAuthor: D_Hall » Tue Jun 24, 2008 11:26 pm

ramses wrote:I don't know if this has been brought up already or not, but at 1x it is telling me the pressure rise for propane should be .59psi, and for MAPP, it should be .29psi.

No, it's telling you that you'll have to *REMOVE* 0.59 psi worth of air if you want an unvented 1X mix in that chamber. Similarly, you'll have to *REMOVE* 0.29 psi of air if you want an unvented 1X mix.

Remember, HGDT was designed for hybrids. As such, it's fueling tool assumes a sealed container, yada yada. Is this ideal for simple combustion gun fueling? Nope.

Good news is that there are plenty of fueling tools for simple combustion guns.

It also assumes that the fuel displaces air at 1x.[/quote]
Umm.... Fuel displaces air at every mix except 0x.
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Unread postAuthor: ramses » Wed Jun 25, 2008 3:06 pm

What you are saying makes sense now. If the pressure rose, it would be like a 1.02x hybrid or something random like that. :oops:

The main problem that I noticed is that it thinks that the percentage for MAPP combustion is half that of propane. It tells me to fill the meter pipe to ~104psi for propane, and ~52psi for mapp. From the wiki, the ratio for MAPP is 4.6% and the ratio for propane is 4.2%, with pressure rise (4.02$ without). I'm sorry about all the confusion, I just thought it was worth mentioning.

I am also running version 0.5.4. I don't know if that has anything to do with the problem
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