I have a draft for a story I'm working on that would involve some kind of large, hundred to thousand metric tonne maximum takeoff weight aircraft duking it out in a near-to-far future setting, but I don't know enough about aerodynamics and aerostatics to fully settle on a main method of propulsion and for lift. The important part is that despite there being no exact clear cut science, my brand of sci-fi tries its best to at least seem like it could be real with the minimal suspension of disbelief - so nothing faster than light, no ridiculous super versatile materials, no magic; most far fetched concepts would be limited "psychic communication" achieved through short-lived nanotechnology, or "linear cannons" which would just be weaponized particle accelerators.
My current idea is that of a class of hybrid airships with turbofan or turboprop engines to produce thrust, and helium or methane to produce lift as well as some wing surface. On the heavier side, I wonder about the upper limit of things like helicopter turboshafts, and airliner-like large wingspans akin to real life examples like the Antonov An-225. Is there any book I could consult, some literature with similar concepts, anything I could use to *enrich* this? I really want to flesh out this idea more until I can convincingly portray combat between these humongous flying beasts. If it's not really feasible, too far into crazy territory, I'd like to know if there's anything I could come up with to have theoretically possible 1,000,000kg flying structures with guns.