think you need to block up all the fingerholes except one & put a canopy over that ....
ah, a canopy, yes indeed : actually on that record cover, the clarinet-based plane on the left has one, it looks more "inhabited" that way : I will try that on a next version of the concept ...
oh yes, and load the intake with black-powder & a canon-ball !!
I hadn't thought of that, but it does look like a sail-vessel canon, seen from the front : a nice contrast in arm technology