Wings Of War Cheats

Once you are in the air on mission mode complete a few objectives once
you have done so a message will appear on the screen that says "BONUS
MISSION", or something like that. Complete the bonus mission to receive
an upgrade of some sort, it's usually an engine upgrade, or weapon
upgrade.

Like the Big Bertha cannons, the tanks are sequestered safely away. On your map, in the circle you need to search, there is a circle made by the lines that indicate roads. This is a town. Search there, flying near the chapel, and the tanks will appear.