just found your world building minibots post (it’s so good 🫶) but i wanted to know why the smallest of the flight frames aren’t considered minibot since a lot of them are unmanned drones which are usual smaller then a VW beetle (14 feet car) like the nasa x - 43 a which is a 12 foot drone in length
Short answer: Because I slacked off and halfassed the research when writing that post big planes fly longer and higher
Long answer:
You've got a very good point there. To be honest, All I had in mind at that time was "hee hee plane big car small". Now that I received your ask, I'll try to give answers that are much more acceptable than that.
The size and weight of an aircraft affects how long it can fly. The bigger the plane, the longer it flies because it can store more fuel. The example you gave me, nasa-X43a was an interesting example, but if my research is correct they could only fly for 10 seconds due to fuel issue.
Moreover, in order to afford engine(s) strong enough to lift them higher, an aircraft has to have some sort of minimum size limit.
I still have no idea how Cybertronian evolution tree would work(not to mention wether it exists or not), but I believe flightframes couldn't afford to go smaller than certain size. Cybertronian spark itself is quite big, and in order to sustain that one needs a reservoir(fuel tank) in case they couldn't find another fuel source for a while. If their size was too small, this could have been a huge problem to their survival.
For now, I'd like to believe that flightframes that are smaller than a car would be mechanimals(robot birds and bats etc). The size limitation I've set for flightframes is BD-5, which is known to be the smallest jet plne(I know this is a manned aircraft, but imagine there is a more powerful equipments inside the cockpit instead of pilot's seat).
These Cybertronians are often called by the nickname of "Pixie Seekers", and they are essentially treated as minis among flightframes. They might look like regular BD-5, but they can fly much faster. They also cannot make a seat for humans as they are designed to be as compact as possible.
Thank you for submitting an ask!