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 71 users online :: 4 registered, 0 hidden and 67 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

Fuel choise

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

Fuel choise

Unread postAuthor: GeoNet » Sun Dec 01, 2013 7:44 am

Hello guys! Im new to spudfiles but not new to spudguns. And right now im making my second one! Just few days back I ordered bbq ignitor from ebay (and I mean that one wich works on batteries, not piesoelectric one) because stunguns are illegal in my country.
But back to my question now! So what you think is best fuel for combustion spud gun? On my old I tried deodorant, airfreshner, hairspray and propane. From these I have came to conclusion that propane is the best because it dont leave anything inside the chamber exept carbon monoxide and water. So it can be easily vented out. The thing is that when my old spudgun was having piesoelectric ignitor and I used hairspray, it left gooey substance inside my combustion chamber and after some time my spark didnt work because spark gaps were covered and I had to make frequent maintenance. So my conclusion here is that I say BIG NO to hairspray!
How about N2O and nitromehtane? I understand that they have faster combustion but will PVC pipes handle that kind of blow?

What do you think?
  • 0


GeoNet
Private
Private
 
Posts: 5
Joined: Sun Dec 01, 2013 6:49 am
Country: Latvia (lv)
Reputation: 0

Re: Fuel choise

Unread postAuthor: jackssmirkingrevenge » Sun Dec 01, 2013 9:03 am

It's all in the wiki ;)

Consider also letting the glory of syringe metering into your life:



For more exotic fuels, consider visiting Rambo's channel on youtube: http://www.youtube.com/user/HomeMadeShow/videos

He is also in Eastern Europe.

He also posted some of his launchers on the forum: combustion-cannon-database/topic25161.html
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Re: Fuel choise

Unread postAuthor: SpudBlaster15 » Sun Dec 01, 2013 10:32 am

All common fuels, with the exception of nitromethane, will have nearly identical performance if you assume the air to fuel ratio is stoichiometric, the gases are mixed uniformly, and other variables such as turbulence in the chamber, temperature, projectile static friction, etc., are reasonably consistent.

Hairspray leaves crap in the chamber and is difficult to meter, so it's obviously a poor choice. Aerosol deodorant leaves less residue but is equally challenging to add in the correct quantity, so it's a poor choice for anything but a basic spray 'n' pray. Starting fluid is the best spray 'n' pray fuel. Propane, butane and propylene are far and away the best choices for a serious cannon, as they are cheap, clean, and easy to meter with either a syringe or onboard volumetric system.

I plan to test nitromethane in an atmospheric combustion launcher at some point, as its performance should be much greater than any standard fuel (~200PSIG peak combustion pressure for stoichiometric air/NM). However, chemical compatibility issues have to be worked out first.

Also, I should point out that using additional oxidizers in a standard gun is not recommended if you don't know exactly what you're doing. The low oxygen content of atmospheric air acts as something of a failsafe, simply rendering the launcher inoperable if you add an excessive amount of fuel. With more exotic oxidizers, it's much easier to turn the chamber into an explosive device. My advice: Stick with air.
  • 1

People should not be afraid of their governments. Governments should be afraid of their people.
User avatar
SpudBlaster15
Major General
Major General
 
Posts: 2385
Joined: Wed Oct 18, 2006 11:12 pm
Location: Canada
Country: Poland (pl)
Reputation: 3

Re: Fuel choise

Unread postAuthor: GeoNet » Sun Dec 01, 2013 3:15 pm

Thank you! That was informative answer! Just what I was looking for! :)

Yes. I assumed that using 100% oxygen would be suicide for PVC spud gun users so I bailed that idea long time ago.
Good! My conclusions about fuel was right! Propane/butane is the best choise for normal-mortal people. :)

But I dont think that syringe is the best idea to find out how much fuel I need for my combustion chamber. I would need to fill 15-30 times to find out. I think I will stick to math and will find out that way.

And one more question. Has someone made any dosage system to lighter refillers? My budget isnt that big that I could buy real propane tank and pressure meter etc. Any suggestions?
  • 0


GeoNet
Private
Private
 
Posts: 5
Joined: Sun Dec 01, 2013 6:49 am
Country: Latvia (lv)
Reputation: 0

Re: Fuel choise

Unread postAuthor: jackssmirkingrevenge » Mon Dec 02, 2013 6:25 am

GeoNet wrote:And one more question. Has someone made any dosage system to lighter refillers? My budget isnt that big that I could buy real propane tank and pressure meter etc. Any suggestions?


Um... a syringe?

I used a simple calculation to see what dose of fuel was needed, then put that amount of fuel in the chamber with a syringe.

You can buy 100mL syringes: http://www.ebay.co.uk/itm/Large-Big-Gia ... 0756664462

100mL of butane is enough to fuel a chamber with a volume of 3.125 litres in a single dose :)
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Return to Combustion Cannon Discussion

Who is online

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

Reputation System ©'