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 50 users online :: 5 registered, 0 hidden and 45 guests


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

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], jimmy101, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

thinking about direct injection

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

thinking about direct injection

Unread postAuthor: F.E.A.R._Sniper » Tue Jan 08, 2008 9:16 pm

ok so i was thinking about building a combustion launcher from some 3/4 pvc and a 2 liter soda bottle. I just want it to shoot paintballs at a fairly low velocity (below 300 fps). I have all my plans and crap worked out and i was wondering what you guys would think about me trying direct injection on this bad boy?

I would do the crack lighter trick to amp up the fuel injection so it wouldn't take forever
  • 0


F.E.A.R._Sniper
Sergeant
Sergeant
 
Posts: 87
Joined: Thu Dec 20, 2007 4:43 pm
Reputation: 0

Unread postAuthor: Novacastrian » Tue Jan 08, 2008 9:20 pm

What exactly do you mean by "direct injection"?
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: Maniac » Tue Jan 08, 2008 9:23 pm

I have all my plans and crap worked out and i was wondering what you guys would think about me trying direct injection on this bad boy?

I would do the crack lighter trick to amp up the fuel injection so it wouldn't take forever


WTF does this mean
  • 0

Coodude26 wrote:
People who laugh really hard at stuff that pisses you off/you getting hurt, who then say "I'm sorry, I can't stop" but you know they easily could.

Mr.C: That's not as easy as you think. It's like me kicking you in the balls and telling you to stop crying.
User avatar
Maniac
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 496
Joined: Tue Oct 23, 2007 5:55 pm
Location: Right behind you
Reputation: 0

Unread postAuthor: Novacastrian » Tue Jan 08, 2008 9:27 pm

I take it a "Crack lighter" is one of those jet cigarette lighters?

Edit: Drugs are bad mmmmk... Don't take drugs mmmmmmmkkk.
  • 0

Last edited by Novacastrian on Tue Jan 08, 2008 9:28 pm, edited 1 time in total.
America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: F.E.A.R._Sniper » Tue Jan 08, 2008 9:27 pm

like a barb is screwed into the chamber and the hose is run off to the fuel source (lighter in this case) and when you push the button it pumps the fuel into the chamber instead of having to spray crap into the chamber by unscrewing everything
  • 0


F.E.A.R._Sniper
Sergeant
Sergeant
 
Posts: 87
Joined: Thu Dec 20, 2007 4:43 pm
Reputation: 0

Unread postAuthor: Novacastrian » Tue Jan 08, 2008 9:31 pm

How does one propose to implement the exchange of dead air for new air?
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: brogdenlaxmiddie » Tue Jan 08, 2008 9:33 pm

you need to greatly elaborate on your question and description :roll:
  • 0


brogdenlaxmiddie
Colonel
Colonel
 
Posts: 562
Joined: Sun Jul 22, 2007 2:19 pm
Country: United States (us)
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: F.E.A.R._Sniper » Tue Jan 08, 2008 9:34 pm

a ball valve between the barrel and chamber that opens to the air so you can vent the chamber. dude I'm not retarded i know that if you don't vent then any unburned gas will make the fuel mix too rich and it won't ignite
  • 0


F.E.A.R._Sniper
Sergeant
Sergeant
 
Posts: 87
Joined: Thu Dec 20, 2007 4:43 pm
Reputation: 0

Unread postAuthor: Isomer » Tue Jan 08, 2008 9:40 pm

"direct injection" is the best way to ensure an optimal fuel mix. Of course with a vent of some sort
  • 0

User avatar
Isomer
Sergeant
Sergeant
 
Posts: 81
Joined: Fri Jan 04, 2008 9:35 pm
Reputation: 0

Unread postAuthor: Novacastrian » Tue Jan 08, 2008 9:40 pm

F.E.A.R._Sniper wrote:a ball valve between the barrel and chamber that opens to the air so you can vent the chamber. dude I'm not retarded i know that if you don't vent then any unburned gas will make the fuel mix too rich and it won't ignite


I did not call you retarded :? That aside are you sure that one ball valve will suffice? Maybe two would be better as you could provide an air flow to really make sure that you have fresh air in the chamber. That said if the barrel extended into the chamber i suppose one valve would be enough.
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: F.E.A.R._Sniper » Tue Jan 08, 2008 9:46 pm

yeah the barrel will go back into the chamber a little bit.

it is actually built like this.

take the bottle and lay it on its side. then stick a short piece of 3/4 down the neck of the bottle and make JSR happy and epoxy it into the neck. on the other end put a tee on there. on the direct opposite side of the chamber place a small section of 3/4 with the ball valve on the other end. from the top of the tee you have enough 3/4 to clear the chamber and then you mount a 90 on there to make the barrel run paralel (sp?) with the chamber. then fire it off some!!!
  • 0


F.E.A.R._Sniper
Sergeant
Sergeant
 
Posts: 87
Joined: Thu Dec 20, 2007 4:43 pm
Reputation: 0

Unread postAuthor: Novacastrian » Tue Jan 08, 2008 9:50 pm

People think that i'm weird when i "suck" on my cannons, i think you may fall into that catagory! :D :P What? it's the best way to ensure a good fuel load!
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: F.E.A.R._Sniper » Tue Jan 08, 2008 9:53 pm

into the "I suck on my cannons" category?
  • 0


F.E.A.R._Sniper
Sergeant
Sergeant
 
Posts: 87
Joined: Thu Dec 20, 2007 4:43 pm
Reputation: 0

Unread postAuthor: Thursto » Tue Jan 08, 2008 10:05 pm

"What? it's the best way to ensure a good fuel load!" Thats what the fine print said in Novacastrian's post if you didnt read it.
  • 0

~ AUSSIE LAND ~
Image
User avatar
Thursto
Major
Major
 
Posts: 389
Joined: Fri Mar 02, 2007 5:11 am
Location: Australia, SA, Adeliade, Para Hills
Reputation: 0

Unread postAuthor: jimmy101 » Thu Jan 10, 2008 12:55 pm

Yes, direct injection from a butane lighter will work fine. Just need a piece of hose with a suitable ID to fit onto the nozzle of the lighter. I've had good luck using the insulation stripped off a piece of 20G wire.
Image (from here)
You can just drill a small hole in the chamber and glue the end of the hose into it. Doesn't have to be all that strong since the force on the junction is going to be pretty small.

You don't need a valve between the chamber and barrel. You can just inject fuel after the ammo is loaded.

Venting will be a PITA. If you have a compressor, or a can of compressed air, you can use that to flush out the chamber between shots by pumping air in through the muzzle. You could just stomp on the bottle a few times to exchange the combustion products for fresh air but that will weaken the bottle pretty quickly.

Might want to put a few packing peanuts in the chamber so you can shake the chamber to get the fuel and air to mix.

This method of fueling is very sensitive to the ambient temperature. The pressure in a butane lighter, and hence the flow rate, is very sensitive to temperature. At 80F the lighter is pressurized to about 2.5 ATM, at 40F it is only about 1.2 ATM.
  • 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

Next

Return to Combustion Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], jimmy101, Yahoo [Bot]

Reputation System ©'