Is it possible to build a jetpack using downward firing machine guns?
The simple answer is yes, depending on the machinegun’s thrust (recoil) to weight ratio.
Then comes the hypothetical lift-pack (it’s not really a jet pack at this point) using 300 AK-47’s.
Then, in true Mythbusters style, the article ramps up. You should RTWT. Especially mounting an A-10’s gun to a Volkswagen. That’s enough there to keep me giggling all day.