[Stoves] venturi system -ratios of air and gas?

[Crispin Pemberton-Pigott]

Dear Dave

" Now, if you mix oxyacetylene and O2 under a trash can or in a balloon, and
ignite the mixture, you do get an explosion.  (The explosion could end very
badly for you and bystanders, so please don't do it.)  I think the important
difference is that instead of a measured rate of gas burning, you have a
large, stagnant volume that, for all practical purposes, ignites all at
once."

Great point!  A school friend of mine found out how they make what sounds
like a machine gun on a biplane at airshows when Snoopy pretends to shoot
down the Red Baron. It is acetylene and oxygen flowing through two
regulators into a gun barrel at the bullet chamber end. At the exit of the
gun barrel the put a spark plug connected to a Model T spark coil (which
sparks all the time).

When the gas mix hits the spark it explodes with a very loud noise and
repeats when the new gas reaches the spark. The frequency is adjusted by
changing the gas flow rate and the barrel length.  The O2-fuel mix can be
adjusted for maximum noise.

It is as loud as a 303 rifle! Budda-budda-budda....

Regards
Crispin