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 51 users online :: 4 registered, 0 hidden and 47 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Why isnt this working?

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
Sponsored 
  • Author
    Message

Why isnt this working?

Unread postAuthor: Spudgun on Crack » Sat Apr 12, 2008 10:25 pm

Today i just finished building my big ass metal pistol. It looked like something out of a sci fi movie, plus it weigh around 3lbs......

I would post a picture but i lost my camera so i will have to looked for it.


I am having some trouble tho, i already got the spark to jump in the metal chamber just fine with a flyback cable but i hit a really weird problem.

My gun is built in the following order.

1in cap, 5in 1in pipe, 1in to 3/4in reducer, 2in 3/4in pipe, 3/4in 1/2in reducer, 2in 1/2in pipe, 1/2in to 1/4in reducer, 6in 1/4 barrel.

It is a really long pistol at around 2 feet.

Here is the problem

It doesn't have any power at all, it barley shot a spit ball 10 feet. (It sounds like a poof)

I have tried all types of fuel from propane, butane, hairspray and others but none seem to have any effect.

Is it a problem with my chamber or is it my sparker(Its a lighter sparker behind a trigger that makes a small spark 3mm)

Any ideas why this isnt working????????????????????
  • 0


Spudgun on Crack
Corporal
Corporal
 
Posts: 79
Joined: Sat Jun 23, 2007 4:43 pm
Reputation: 0

Unread postAuthor: DYI » Sat Apr 12, 2008 10:37 pm

Wait, did you really mean that the barrel is only 6" long? Because if it is, you're not going to get any power out of it without several thousand psi.

Try it at 30x. If you survive, you'll notice that power has improved to the point that it's almost as powerful as a small pellet gun.
  • 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

Unread postAuthor: bigbob12345 » Sat Apr 12, 2008 11:05 pm

Well DYI is completely right
make the barrel something like 24in long and I guarrentee it will work
  • 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: Spudgun on Crack » Sat Apr 12, 2008 11:52 pm

No problem, i can get the barrel up to 24in but i will have to buy 3 more 6in 1/4in pipes and 2x1/4in couples but other than that it should be fine.

I was almost at the point of mixing oxygen in with the mix because this is a metal chamber that can take a lot more punishment that pvc but that could be dangerous.
  • 0


Spudgun on Crack
Corporal
Corporal
 
Posts: 79
Joined: Sat Jun 23, 2007 4:43 pm
Reputation: 0

Unread postAuthor: Blitz » Sat Apr 12, 2008 11:55 pm

You can't get larger nipples? Most lengths of steel pipe are threaded on both ends. It would be much cheaper, practical, and more effective is the barrel is one piece.
  • 0

User avatar
Blitz
Colonel
Colonel
 
Posts: 621
Joined: Sat Apr 07, 2007 1:48 am
Location: West Chicago, IL
Reputation: 0

Unread postAuthor: TurboSuper » Sat Apr 12, 2008 11:56 pm

Also, 1 in is a pretty small diameter chamber. I've noticed that when you decrease the diameter, the power seems to go with it.

But increasing the barrel length should at least give it some decent range.
  • 0

"If at first you dont succeed, then skydiving is not for you" - Darwin Awards

TurboSuper
Brigadier General
Brigadier General
 
Posts: 986
Joined: Thu Jun 16, 2005 1:44 pm
Reputation: 0

Unread postAuthor: Blitz » Sat Apr 12, 2008 11:59 pm

Because the smaller the diameter, the less flow there is to the barrel.
  • 0

Last edited by Blitz on Sun Apr 13, 2008 3:19 pm, edited 1 time in total.
User avatar
Blitz
Colonel
Colonel
 
Posts: 621
Joined: Sat Apr 07, 2007 1:48 am
Location: West Chicago, IL
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: jrrdw » Sun Apr 13, 2008 4:38 am

Blitz wrote:Because the smaller the diameter, the less flow there is to the valve.


What valve? Did you mean flow through the barrel?
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6539
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: psycix » Sun Apr 13, 2008 5:52 am

Blitz wrote:Because the smaller the diameter, the less flow there is to the valve.


WRONG!
Its combustion matey!

The smaller the chamber diameter, the longer it has to be for a specified volume.
The longer the chamber is, the more the flamefront has to travel, thus the more ineffective your combustion will occur.
The optimal chamber shape is a spere with the ignition in the middle or in cillindric shapes, about the same diameter as length.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: Blitz » Sun Apr 13, 2008 11:51 am

Gah, yes I meant barrel. Edited. :P
  • 0

User avatar
Blitz
Colonel
Colonel
 
Posts: 621
Joined: Sat Apr 07, 2007 1:48 am
Location: West Chicago, IL
Reputation: 0

Unread postAuthor: D_Hall » Sun Apr 13, 2008 12:17 pm

psycix wrote:Assuming a single ignition point, the optimal chamber shape is a spere with the ignition in the middle or in cillindric shapes, about the same diameter as length.

I fixed your post. ;)
  • 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: jrrdw » Sun Apr 13, 2008 1:56 pm

Did you try different size spark gaps along with different amounts of fuel?
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6539
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: psycix » Mon Apr 14, 2008 5:34 am

D_Hall wrote:
psycix wrote:Assuming a single ignition point, the optimal chamber shape is a spere with the ignition in the middle or in cillindric shapes, about the same diameter as length.

I fixed your post. ;)


Agree! Thanks :)
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Return to Combustion Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'