Resorted to lighter (dutiful daughter's suggestion).IGNITION! Purely via heat.

Post launch. Note the back-blast, as well as the flame!

LAUNCH! Note the after-blast distorting the flames from the projectile! Isn't this cool?

The penis cannon: It shoots, it wilts! (Sometimes, it backblasts.)

Another view, showing that the bend in the cannon occurs after the launch, due to melting of

the aluminium?