Well, hey there! I guess my ears were burning, but I randomly popped back in here and saw this!
: I like where you're heading! As Duion mentioned, I did a fairly significant amount of work in this direction, which has been somewhat on the back burner now for a while but I'd love to compare notes.
The direction I took was A) a terrain pager, using flightgear as a source for terrain data over a socket connection to my running Torque instance. My implementation was far from perfect (among other things it desperately needs to be threaded, so the game engine doesn't pause while new terrain tiles are loading) but it did provide a walkable/flyable T3D copy of the FlightGear terrain, broken into (I think) 2.56 km square tiles.
And then for the aircraft, I used B) the UDP streaming capability of FG to give me position and orientation of the aircraft, which I then hooked up to drive FG aircraft models, imported into Torque through the collada format. For animations, I got far enough to do things like rotate the helicopter blades according to the rotation speed exported from FG, and switching between the rotor models of single blades to the transparent disc-like shapes as speed increased.
I didn't solve the floating point precision problem once and for all, but worked around it for local flights by centering my local map at a local origin and working outward from there. For long distance flights there would have to be a way to shift everything to a new local origin when the player gets too far away from the last one.
Here are a couple of videos documenting some parts of what I got done:
This one is a KA50 helicopter with working textures and rotors, sitting on the ground spinning up the engine: https://vimeo.com/151305170
This is an earlier version, with no rotors or textures, but an example of the flight dynamics: https://vimeo.com/147692291
And here's one with a fixed wing aircraft, the Dragonfly ultralight: https://vimeo.com/147553155
The programmer art is strong in these, but if you've spent much time in FlightGear you might appreciate some of the subtleties like the crisp, clear working shadow of the aircraft on the ground.
One of the main motivations for me in doing this was to create an environment where users could fly all (or at least some number of) the FG aircraft in the presence of skinned, convincing human models with actual animations. I'd love to see (or create) a low flying, air vs. ground combat simulation, for example, using FG for the flight dynamics and Torque for the animated characters, particle effects, and everything else.
Anyway, welcome to the forums, and thanks for your shared interest! Best of luck and let me know if I can help!