Help

[wyz2285]

Some one plz help me,I'm really new at combustion cannons.
And i'm trying to make a mini one first,i used a chamber fan,a spark ignitor, using a mix of butane and propane.But a can't get it ignited!! some body plz tell me why and what's the basic things i need to make a good mini combustion cannon?thanks

[jackssmirkingrevenge]

How are you getting fuel into your chamber? Getting the correct fuel/air ratio (around 4% in your case) is very important for reliable function, especially in smaller combustions.

You might want to consider using a syringe:

[wyz2285]

how does it works, i do like to build a fuel inject system,but don't know how

[jackssmirkingrevenge]

Ok, what is the volume of your chamber?

[wyz2285]

i think is about 300cm2

[jackssmirkingrevenge]

So, grab a syringe and lighter setup like in the photo above, measure 12mL of fuel, inject it into your chamber, voila

[wyz2285]

so i have to take out the syringe for the lighter frist?than inject in to the chamber?

[jackssmirkingrevenge]

Yes.

Don't worry about the gas leaking out of the nozzle while you do that

[wyz2285]

ok,that's easy.but is there some way that i can do it with out move the syringe?

[POLAND_SPUD]

what do you mean by

with out move the syringe

??
you can use manometric metering but, AFAIK, it is a bit trickier to get right than this method

[jackssmirkingrevenge]

You could also have a valve between the syringe and the chamber, which is closed when you fill the syringe, then open it and push in the plunger.

You'd also need a way to vent the chamber though.

[wyz2285]

thanks,this helps a lot