This is awesome!
It reminds me of a sci-fi story I read probably 20 years ago where these people lived on two planets that orbited each other closely enough that their atmospheres mixed. They would travel between the two planets by balloon. They take off and float so high that the other planet’s gravity took over.

Seconded. Sounds like a good book even if scientifically flawed/improbable.

With flying ships you’d think that the cannons would have swivel room for up, down, left, right, up-left, up right…