The model needs to be triangles, that's what's causing the broken appearance (so only 3 points out of each quad were exported). Not sure why it's upside down though, since the bones don't get inverted.
Aha! So that's why all of Uber's models are made up of triangles! I was curious about that while I was messing around with some in the past. Why is this exactly? Is it less resource intensive or what? I'd find it a bit more cumbersome to have to divide each square into triangles when creating a model... Also, for nuketf all models are made up of flat plane triangles, I might want to add, rather than solid blocks.
I actually figured out it's quite simple to break a mesh apart into triangles. I can do it by going into the mesh's properties while I have a face selected. "break apart into triangles" or something along those lines. It might make it easier on a system? I'm unsure.
Press W > Flip Normals (also found under mesh tools > Normals). This will flip the selected faces. A way to tell if they are the right way around is change the Viewport Shading to Textured: If you've applied a texture, you should see it normally, or if you haven't, the model should appear white. If the normals are incorrect, you'll instead see something like this (easiest to see in edit mode with the model selected): It actually appears some faces are the wrong way and some aren't, so you'll need to look at the parts individually (you can hide selected faces with H, and un-hide all with Alt-H - this will make it easier to view certain parts by themselves). The parts that need to be flipped appear to be the main chassis, the underside of the tracks, the barrel and front of the turret (except for the top face).
i fixed them aaaand...only the tracks and the part under the chassis appers not thwe Turret or barrel or the main hull just the tracks and a flat pice under them...
I keep having the same problems ingame for my model, I just tried flipping the normals but can't actually test it yet, which is saddening. But yeah- you're not alone here.
How much of it is invisible? Can you send me a picture? Edit: It seems like pretty much everything but the back tracks are correct. Maybe it's because the bones are connected via the general area around them rather than to particular parts of the mesh? (I'm still trying to find out how to connect a certain part of the mesh to particular bones rather than the whole mesh to the whole thing... or alternatively using weights. There is no comprehensive tutorial on manual rigging... ANYWHERE that I can find.)
I think it actually is turned upside down but all the faces are showing up correctly on the bottom, try exporting it then importing it back, is it upside down in Blender?
Then something weird is happening. o.o I wonder if anyone has ever successfully put in a custom model into the game other than Raevn... (Though the game crashed after a bit when he put the TA commander into the game.)
OH! I know how to fix this. All I need you to do is... Create a new model, except without the mesh being all connected. As in, if I select all the faces for the top of the tank, it shouldn't move the bottom of the tank. Afterwards- I can rig it for you. Edit: Basically make a new model that doesn't do this.