I have noticed a plethora of cannons are starting to incorporate fans in the combustion chambers. Could someone shed some light on the purpose of this?

Also, if you happen to have some links to some guides of how to do it I would appreciate that.

holy shit it worked i love you and if i was a lady i would make sweet love to you

I recently put together a PVC Sched 40 spud cannon following one of the guides on this site. I used a 1.5" diameter barrell which is about 3.5 feet long. The combustion chamber (attached to the barrell through the reducer) is about a foot long and its diamter is 3". The other end of the combustion c...