It took me a while, but I finally realized how to beat this damn mission. Here's the deal:
1. You ABSOLUTELY need the Proximity Fuse and the Methanol Fuel Injection upgrades, for quicker kills and 20% increased speed, respectively. It is good to also have good armor, so you don't have to worry too much aboutbeing shot,and Stall Strips, so you canmake quicker turns.
2. You ABSOLUTELY need to blast all primary (red) targets, including planes, tanks, and armored cars. EVERYTHING "red" needs to be killed, no exceptions, or you will fail the mission. Orange (secondary) targets should be ignored unless you need extra ammunition.
3. Keep Cowboy's attack active at all times, andkeep Milo and Teach in attack mode always.
4. Here is the sequence of events:
A) After the parade sequence, and when the German attack starts, get your wingmen in attack mode and start blasting primary targets as quickly as you can. It does not matter if you kill planes, tanks, or armored cars first, just kill them all ASAP.
B) As soon as you kill the last primary target, you will be prompted to act as a spotter for Katyusha rocket batteries. Open up your tactical map, and head towards the large column of tanks. When they are in your sights, press X, and avoid the rocket barrage. After the rocket barrage, mop up remaining tanks with missiles.
C) You will then be prompted to take out flak gun emplacements. Again, put them in your sights, press X, avoid the Katyusha rockets, as well as AA flak, and mop up remaining gun emplacements. You must take them ALL out.
D) For the final part of the mission, you will need to take out a "super gun". Fly high in its opposite direction, turn around, descend towards it as slowly as you can, and put the super gun in your sights. When the cannon emplacement door opens, start firing missiles at it. When you run out, blast it with your machine guns. Two or three runs should do this.
AND YOU ARE DONE! Collect your achievements, pick up a beer (or an extra-caffeinated coke if you are underage), and smile! You've earned it!