Ziggomorphic has discovered a very interesting hidden feature of the game. It seems the developers created an UFO in the game that is flyable. Normally it is inaccessible but by using the UpExtract tool, we can extract files about an object called AuUfo. With a little renaming of the UFO files to match an in-game plane such as the Dauntless, we can fly a UFO in the game.Click
here to download the files you need. Extract the zip contents to your game folder on your disk. This temporarily replaces the Komet jet plane with the UFO and you can choose to fly the UFO in the game. The replacement of the Komet is temporary and you can return the normal Komet textures and model by removing the UFO files from your game folder. Replacing the Komet gives the UFO a more spacecraft engine noise (as opposed to a propeller noise) and high speed.
Screenshots
I took a few screenshots whilst trying out the UFO. The UFO doesnt seem to have a primary weapon coded in so I couldn't get far on mission 1 where I tested it.
Other models
Just for a laugh I tried the same principle with the zepplin/airship from mission 10 and I was able to fly it albeit with a poor view. The textures weren't visible on the zepplin but this was most likely my fault when setting it up.
I bet that most of the models can be flown using the technique show above (remember the cheat code where you can drive the car?). Send you best screenshots of new models and I will post them.