Right, sorry. I messed up a bit. When I said "sub-orbital" I meant not going into orbital height. More specifically I'm trying to make a long-distance plane that can reach 15k meters tops. So I was wondering what type of engine can get me halfway around the world and back, how much weight it should have, the type of wings. That sort of thing. The trim and precision controls sound useful, I'll be sure to play around with them to see what they do.
As for mods, I'm trying to avoid them because I want to explore the game in its vanilla state before I start messing around. Thanks for the recommendation though, I'll be sure to keep it in mind.