Chamber Venting with compressed air.

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
User avatar
ramses
Staff Sergeant 2
Staff Sergeant 2
United States of America
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm

Sat Aug 15, 2009 9:22 am

GalFisk wrote: using vacuum from the projectile in an overly long barrel).
The long barrel is not necessary if a piston valve type thing is used as a burst disk. My piston hybrid pulls a lot of vacuum when I open the fill valve. This is because the valve closes at say 10psi while the air is at a high temperature. When the gas cools, it contracts, leaving a vacuum.
POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
GalFisk
Specialist
Specialist
Sweden
Posts: 113
Joined: Mon Feb 28, 2005 4:06 am
Been thanked: 4 times

Wed Aug 19, 2009 4:10 am

The thing is, pulling a vacuum is not enough because we need to fill the entire chamber with fresh air for s sustainable cycle. If we have hot exhaust gasses that contract to 10% of their original volume, only 90% of the chamber will fill with fresh air and the next shot will only be at 90% power. This will mean even less air and less power for subsequent shots, until there's not enough air left to sustain the cycle.
we know that a regular valved pulsejet will draw in enough air for a sustained cycle, the question is if the projectile hindes this cycle or helps it.
User avatar
ramses
Staff Sergeant 2
Staff Sergeant 2
United States of America
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm

Thu Aug 20, 2009 4:14 pm

GalFisk wrote:This will mean even less air and less power for subsequent shots, until there's not enough air left to sustain the cycle.


No, the gas from cycle 2 will also draw in 90% of the chamber volume, too. then all the gas would be heated, contract to 10% and so on until the chamber heated up to the point where, yes, the cycle would stop. So an active cooled metal chamber would be a great idea.
POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
Moonbogg
Staff Sergeant 3
Staff Sergeant 3
United States of America
Posts: 1733
Joined: Mon Oct 13, 2008 10:20 pm
Location: SoCal
Has thanked: 160 times
Been thanked: 100 times

Thu Aug 20, 2009 7:09 pm

Actually, Ragnarok, I believe the CO2 causes the slowing of molecules, which in turn bores the pants off the fire, causing it to go to sleep.
User avatar
chenslee
Specialist
Specialist
Posts: 147
Joined: Thu Jan 29, 2009 2:25 pm

Donating Members

Thu Aug 20, 2009 8:24 pm

Moonbogg wrote:Actually, Ragnarok, I believe the CO2 causes the slowing of molecules, which in turn bores the pants off the fire, causing it to go to sleep.
THAT'S NOT WHAT HAPPENS YOU ARE STUPID.

It blows out the fire like the big bad wolf, actualy the one in Ragnarok's user pic.

Image

I mean just look at that triple fire suppression wolf breath.
GalFisk
Specialist
Specialist
Sweden
Posts: 113
Joined: Mon Feb 28, 2005 4:06 am
Been thanked: 4 times

Fri Aug 21, 2009 4:44 am

ramses wrote:
GalFisk wrote:This will mean even less air and less power for subsequent shots, until there's not enough air left to sustain the cycle.


No, the gas from cycle 2 will also draw in 90% of the chamber volume, too. then all the gas would be heated, contract to 10% and so on until the chamber heated up to the point where, yes, the cycle would stop. So an active cooled metal chamber would be a great idea.
Wouldn't cycle 2 draw in less air, because it has less fuel and therefore generates less heat/expansion/vacuum?
User avatar
ramses
Staff Sergeant 2
Staff Sergeant 2
United States of America
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm

Fri Aug 21, 2009 1:52 pm

cycle 2 would draw in less air, but every cycle after it would draw in as much as cycle 2 did. Actually a bit less as the chamber heats up, but that can be controlled.
POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
Davidvaini
Sergeant 4
Sergeant 4
Posts: 1315
Joined: Tue May 29, 2007 8:58 pm

Fri Aug 21, 2009 2:01 pm

chenslee wrote:
Moonbogg wrote:Actually, Ragnarok, I believe the CO2 causes the slowing of molecules, which in turn bores the pants off the fire, causing it to go to sleep.
THAT'S NOT WHAT HAPPENS YOU ARE STUPID.

It blows out the fire like the big bad wolf, actualy the one in Ragnarok's user pic.

I mean just look at that triple fire suppression wolf breath.
yeah and thats not what happens here. We dont like people who insult. Calling someone stupid, especially in all caps is not accepted here. This is a peaceful community that likes to share knowledge and have fun.

regardless if the person is wrong.. you don't call them stupid. You point out they were wrong and let them know why.
User avatar
chenslee
Specialist
Specialist
Posts: 147
Joined: Thu Jan 29, 2009 2:25 pm

Donating Members

Fri Aug 21, 2009 3:04 pm

chenslee wrote: THAT'S NOT WHAT HAPPENS YOU ARE STUPID.
I apologize. I was trying to be sarcastic and funny and I guess it came off ruder than I intended. In addition to this, I was blatantly hijacking the thread.

My previous post should have read:

That's not what happens, you are insufficiently informed. Unless I am mistaken (and I often am) fires do not have pants.
Post Reply