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 37 users online :: 5 registered, 0 hidden and 32 guests


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

Registered users: Bing [Bot], Exabot [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

a spark question.

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

a spark question.

Unread postAuthor: stevenarroyo » Thu Sep 25, 2008 9:55 am

ok people i have a new question......
am going to use a electric BBQ ignitor and i spark plug. first do you think it can work?? and am planing on having it on the elbow before the barrel.
here is a picture of what an talking about....
<a href="http://s217.photobucket.com/albums/cc216/stevenarroyo/?action=view&current=IMG00295.jpg" target="_blank"><img src="http://i217.photobucket.com/albums/cc216/stevenarroyo/IMG00295.jpg" border="0" alt="Photobucket"></a>
my question for that is do you think it will work there?? if not where can i put it that will not get in the way??
  • 0

User avatar
stevenarroyo
Master Sergeant
Master Sergeant
 
Posts: 155
Joined: Sun Jul 27, 2008 7:50 pm
Location: Miami, FL
Reputation: 0

Unread postAuthor: psycix » Thu Sep 25, 2008 11:12 am

Why do you ask this question both in your existing thread AND in this one?


Yes, it will work, no matter where it is placed in the chamber.
Do note that when it is somewhere far away form the injection point you need to mix it well with a fan.
Also, burn rates are better when the gap is more to the center of the chamber.
  • 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: stevenarroyo » Thu Sep 25, 2008 11:27 am

o ok thanks

do u know what type of treads are on the spark plug??
  • 0

User avatar
stevenarroyo
Master Sergeant
Master Sergeant
 
Posts: 155
Joined: Sun Jul 27, 2008 7:50 pm
Location: Miami, FL
Reputation: 0

Unread postAuthor: jimmy101 » Thu Sep 25, 2008 11:37 am

Like psycix said. You probably want the gap on the central axis of the chamber (which a spark plug can't do since it is too short) and you want the gap near the front to back center of the chamber.

Oh, and it also helps if the gap is near the fan. As drawn, there won't be much movement of the fuel at the spark gap, even with a fan running.

But you probably want the fan near the clean out plug or else it'll get destroyed when the gun is fired.

Net result of all this? Do it the way 90% or all combustion guns are done when they have a single gap;
1. Use pointy screws (like fine thread drywall screws) for the gap, not a spark plug.
2. Position the gap at about the center of the chamber (you can ignore the volume of the elbows when determining the "center" of the chamber).
3. Mount the fan near the cleanout plug with the air directed at the spark gap.

Also remember that for an over-and-under design you need pretty good bracing between the barrel and chamber, the elbows aren't enough.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3129
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: stevenarroyo » Thu Sep 25, 2008 11:40 am

i know i need more bracing, am going to use wood or maybe some pvc i have around
  • 0

User avatar
stevenarroyo
Master Sergeant
Master Sergeant
 
Posts: 155
Joined: Sun Jul 27, 2008 7:50 pm
Location: Miami, FL
Reputation: 0

Unread postAuthor: nickz » Fri Sep 26, 2008 6:26 am

stevenarroyo wrote:o ok thanks

do u know what type of treads are on the spark plug??


Use A 1/4" NPT tap, It will fit tight.
  • 0


nickz
Private First Class
Private First Class
 
Posts: 32
Joined: Mon Mar 26, 2007 2:30 pm
Reputation: 0

Unread postAuthor: stevenarroyo » Fri Sep 26, 2008 5:22 pm

thanks nickz.

but will the spark plug work? cause i was looking on the site and some1 was talking about it not working?? and i want to know before i make a big hole in my cannon.
  • 0

User avatar
stevenarroyo
Master Sergeant
Master Sergeant
 
Posts: 155
Joined: Sun Jul 27, 2008 7:50 pm
Location: Miami, FL
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: DYI » Fri Sep 26, 2008 8:09 pm

Use A 1/4" NPT tap, It will fit tight.


I've never encountered a spark plug in my life that had 1/4" NPT threads. Not saying they don't exist, but you'd probably have a bit of trouble finding one.

Most modern spark plugs have some oddball metric threads (or at least they're odd on this side of the pond). Ye olde fashioned Model T spark plugs are 1/2" NPT threads (yeah, they're really big), but they're also kind of weak. I doubt this would be a problem on normal combustion guns, but I've blown 2 of them in half, consecutively.

but will the spark plug work? cause i was looking on the site and some1 was talking about it not working?? and i want to know before i make a big hole in my cannon.


Do you mean "will a device that is designed to allow electric arcs to occur inside the cylinders of an engine to ignite a gaseous hydrocarbon/oxidiser mix (at over 100 psi in some cases) be able to ignite a very similar gaseous hydrocarbon/oxidiser mix inside my spudgun at the same voltage, with better mixing and lower pressure?" :P
  • 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: stevenarroyo » Fri Sep 26, 2008 8:16 pm

yes i am

i was looking on the site and the guy said it was not working then he put 2 screws and started to fire good.
  • 0

User avatar
stevenarroyo
Master Sergeant
Master Sergeant
 
Posts: 155
Joined: Sun Jul 27, 2008 7:50 pm
Location: Miami, FL
Reputation: 0

Unread postAuthor: nibbler125 » Fri Sep 26, 2008 8:32 pm

make a bracket inside of the combustion chamber using wood and set 2 to 3 spark gaps just two wire pieces stapled to a 1" 1" 1" piece of wood spanning the distance of the cannon and use hot glue to make sure it wont go nowhere but make sure to test it to make sure it can gap ok before you glue it together.
  • 0


nibbler125
Sergeant
Sergeant
 
Posts: 80
Joined: Sat Jun 07, 2008 10:42 am
Reputation: 6

Unread postAuthor: stevenarroyo » Fri Sep 26, 2008 8:36 pm

:? am thinking of making something like that.... but out of some PVC i have around. maybe i do that am alright getting some good ideas in my head :twisted:
  • 0

User avatar
stevenarroyo
Master Sergeant
Master Sergeant
 
Posts: 155
Joined: Sun Jul 27, 2008 7:50 pm
Location: Miami, FL
Reputation: 0

Unread postAuthor: nickz » Sat Sep 27, 2008 8:01 am

DYI wrote:
Use A 1/4" NPT tap, It will fit tight.


I've never encountered a spark plug in my life that had 1/4" NPT threads. Not saying they don't exist, but you'd probably have a bit of trouble finding one.

Most modern spark plugs have some oddball metric threads (or at least they're odd on this side of the pond). Ye olde fashioned Model T spark plugs are 1/2" NPT threads (yeah, they're really big), but they're also kind of weak. I doubt this would be a problem on normal combustion guns, but I've blown 2 of them in half, consecutively.

but will the spark plug work? cause i was looking on the site and some1 was talking about it not working?? and i want to know before i make a big hole in my cannon.


Do you mean "will a device that is designed to allow electric arcs to occur inside the cylinders of an engine to ignite a gaseous hydrocarbon/oxidiser mix (at over 100 psi in some cases) be able to ignite a very similar gaseous hydrocarbon/oxidiser mix inside my spudgun at the same voltage, with better mixing and lower pressure?" :P


I didnt say it was 1/4 npt I jsut said to use a 1/4 npt tap.

compare them for yourself.
  • 0


nickz
Private First Class
Private First Class
 
Posts: 32
Joined: Mon Mar 26, 2007 2:30 pm
Reputation: 0

Unread postAuthor: nickz » Sat Sep 27, 2008 8:02 am

DYI wrote:
Use A 1/4" NPT tap, It will fit tight.


I've never encountered a spark plug in my life that had 1/4" NPT threads. Not saying they don't exist, but you'd probably have a bit of trouble finding one.

Most modern spark plugs have some oddball metric threads (or at least they're odd on this side of the pond). Ye olde fashioned Model T spark plugs are 1/2" NPT threads (yeah, they're really big), but they're also kind of weak. I doubt this would be a problem on normal combustion guns, but I've blown 2 of them in half, consecutively.

but will the spark plug work? cause i was looking on the site and some1 was talking about it not working?? and i want to know before i make a big hole in my cannon.


Do you mean "will a device that is designed to allow electric arcs to occur inside the cylinders of an engine to ignite a gaseous hydrocarbon/oxidiser mix (at over 100 psi in some cases) be able to ignite a very similar gaseous hydrocarbon/oxidiser mix inside my spudgun at the same voltage, with better mixing and lower pressure?" :P


I didnt say it was 1/4 npt I just said to use a 1/4 npt tap.

compare them for yourself.
  • 0


nickz
Private First Class
Private First Class
 
Posts: 32
Joined: Mon Mar 26, 2007 2:30 pm
Reputation: 0

Return to Combustion Cannon Discussion

Who is online

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

Reputation System ©'