I agree that tanks should have a machine gun. It should be coaxial (i.e. it fires in line with the main gun), it should have the same range as the guns on the fighters, and there should be a limited amount of ammo (also for the main gun). The advantage is still with the fighters because of their greater maneuverability and ease of aiming (the fighter aims by pointing the nose of the plane while the tank gunner has to traverse the turret). Also, the machine gun can only elevate the same as the main gun. This would give the tanks some self defense capability on the move without giving them too much advantage relative to the fighters. In reality of course the fighters would never be able to defeat the tank with the .30 caliber machine guns typical of that era, but it does add excitement to the game.