Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 76 users online :: 4 registered, 0 hidden and 72 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

another hgdt question

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.
Sponsored 
  • Author
    Message

another hgdt question

Unread postAuthor: pat123 » Sat Apr 19, 2008 10:15 pm

look at the chamber temperature is that right? over 3500 degrees fahrenheit :shock:

and what is chamber burnout?
  • 0

Attachments
big hybrid hgdt.JPG
User avatar
pat123
Colonel
Colonel
 
Posts: 514
Joined: Sat Dec 23, 2006 10:08 pm
Location: S.C.
Reputation: 0

Unread postAuthor: D_Hall » Sat Apr 19, 2008 10:40 pm

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. ;)
  • 0

Simulation geek (GGDT / HGDT) and designer of Vera.
User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: pat123 » Sat Apr 19, 2008 10:49 pm

can a sch 40 steel pipe handle 3500 degrees?
  • 0

User avatar
pat123
Colonel
Colonel
 
Posts: 514
Joined: Sat Dec 23, 2006 10:08 pm
Location: S.C.
Reputation: 0

Unread postAuthor: bigbob12345 » Sat Apr 19, 2008 10:55 pm

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: )
  • 0

User avatar
bigbob12345
Major General
Major General
 
Posts: 1516
Joined: Sat Dec 01, 2007 9:13 am
Location: Mercer Island,Washington
Reputation: 0

Unread postAuthor: SpudFarm » Sun Apr 20, 2008 6:33 am

steel can handle the temp..
it is in a very few ms.
  • 0

"Made in France"
- A spud gun insurance.
User avatar
SpudFarm
Donating Member
Donating Member
 
Posts: 2563
Joined: Sat Nov 04, 2006 9:39 am
Location: Norway Trondheim area
Reputation: 0

Unread postAuthor: VH_man » Sun Apr 20, 2008 6:57 am

whats with the "insulation" part? my FPS increases significantly when i insulate my chamber........... wich kind of baffles me.
  • 0

User avatar
VH_man
Major General
Major General
 
Posts: 1827
Joined: Sat Dec 09, 2006 6:00 pm
Location: New Hampshire
Reputation: 1

Unread postAuthor: DYI » Sun Apr 20, 2008 9:19 am

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.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Sponsored

Sponsor
 


Unread postAuthor: pat123 » Sun Apr 20, 2008 10:14 am

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
  • 0

User avatar
pat123
Colonel
Colonel
 
Posts: 514
Joined: Sat Dec 23, 2006 10:08 pm
Location: S.C.
Reputation: 0

Unread postAuthor: boilingleadbath » Sun Apr 20, 2008 10:19 am

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.
  • 0

User avatar
boilingleadbath
Moderator
Moderator
 
Posts: 1642
Joined: Sat Mar 12, 2005 10:35 pm
Location: Pennsylvania, USA
Reputation: 0

Unread postAuthor: jimmy101 » Sun Apr 20, 2008 11:01 am

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.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3128
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: JDP12 » Sun Apr 20, 2008 7:12 pm

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
  • 0

"Some say his pet elephant is pink, and that he has no understanding of "PG rated forum". All we know is, he's called JSR. "
User avatar
JDP12
Major General
Major General
 
Posts: 1943
Joined: Fri Mar 30, 2007 8:34 pm
Reputation: 0

Return to Hybrid Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], Yahoo [Bot]

Reputation System ©'