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another hgdt question

Posted: Sat Apr 19, 2008 10:15 pm
by pat123
look at the chamber temperature is that right? over 3500 degrees fahrenheit :shock:

and what is chamber burnout?

Posted: Sat Apr 19, 2008 10:40 pm
by D_Hall
Yeah, propane burns hot, ya know.

Chamber burnout = The point at which all fuel/air in the chamber have burned. Note that this is NOT the same thing as all fuel/air in the entire system.... When the disc bursts, unburned fuel/air is pushed into the barrel. This fuel/air is NOT burned at the time of chamber burnout.

Now, I'll give you three guesses as to what the meaning of Bar Burnout is. ;)

Posted: Sat Apr 19, 2008 10:49 pm
by pat123
can a sch 40 steel pipe handle 3500 degrees?

Posted: Sat Apr 19, 2008 10:55 pm
by bigbob12345
Well what does everybody use to make hybrids?
And do they have problems with the heat?

The high temp happens so shortly that even pvc chambers wont be affected at all(other than the fact it may burst from the extreme pressure generated :roll: )

Posted: Sun Apr 20, 2008 6:33 am
by SpudFarm
steel can handle the temp..
it is in a very few ms.

Posted: Sun Apr 20, 2008 6:57 am
by VH_man
whats with the "insulation" part? my FPS increases significantly when i insulate my chamber........... wich kind of baffles me.

Posted: Sun Apr 20, 2008 9:19 am
by DYI
whats with the "insulation" part? my FPS increases significantly when i insulate my chamber........... wich kind of baffles me.
Insulation decreases heat loss, all pressure in chamber is heat, etc...

And I'll bet that the reason the burnout messages came up is because your chamber is so ridiculously oversized in comparison to your barrel. Something to do with the fact that the gases haven't fully burned until quite a while after the projectile leaves the barrel.

Posted: Sun Apr 20, 2008 10:14 am
by pat123
And I'll bet that the reason the burnout messages came up is because your chamber is so ridiculously oversized in comparison to your barrel.
probably 28.5:1 c:b ratio

Posted: Sun Apr 20, 2008 10:19 am
by boilingleadbath
The wall never gets very hot, because the gases don't transfer heat to the wall very fast, at least compared to the rate of heat conduction inside the wall. This holds true even in plastics.

Posted: Sun Apr 20, 2008 11:01 am
by jimmy101
Not only do the gases transfer heat relatively slowly, but more importantly, there just isn't that much energy in the gases. Doesn't really matter how hot the gases are, the mass of the gases is so small compared to the mass of the gun that the temperature rise of the gun is minimal.

Even in a closed chamber plastic has no problem handling the heat in the combustion gases. A moderate sized PVC chamber buring 1x propane in air only heats up couple degrees C. The thin layer of PVC in actual contact with the gases gets hotter, but it still isn't hot enough to affect the plastic.

Posted: Sun Apr 20, 2008 7:12 pm
by JDP12
2 things: 1) what is ignition number? number of spark gaps?

2) why is there a blue line as well? Whenever i run it i only get a red line