I'm going to do this in 3 layers.
Most basicly, it's a FASA-esque hexsheet wargame, using d10.
At the medium level, there are two very interesting factors about it:
The damage system is a modified version of RL:Centurion.
The movement system plays like a simplified version of Airforce.
If the above two references mean nothing two you.
Each plane has a record sheet, that consists of a gridded layout of all the important parts of the plane in an approximate +-shape (ie, fuselage with wings sticking out the side). Then there are layers of armour at the front and back. The different weapons have one or more 2d profiles of damage. When a weapon hits it damages all the armour and components under the profile, starting at the outermost part of the area you hit. Quite hard to explain, might need to see a picture of it somewhere.
There is a movement diagram which shows all the possible legal moves based on your plane's current position. Each maneouver has a required speed and wing stress indicators. You select a maneouver for your plane. If it has the necesarry engine speed, acceleration and turn strength, no problem. If not, you have to make a pushing the envelope test to succeed, otherwise you give your plane stress fractures and end up somewhere unexpected. Currently, I can't remember whether it was pre-plotted or turn about.
Does that help?
