Any help on how to beat this damn mission would be extremely appreciated.

First, Engage and destroy the FW190 partol. Then go to the hangar 2nd to the left of the factory. Blow up the BACK hangar door. Then turn left and take out the factory. You get a checkpoint and by now 3 more 190s will be on you. Take em out. Then before the 109s can catch you, land at the partisan airfield, come up and take out JUST ONE 109. Land again. Take out another. Land again and take out the last one, then blow up the remaining 109s the same way, near the partisan airfield. After the skies are clear, blow up the Ju390 in the already opened hangar. Then destroy the front hangar door on any hangar you choose. This will start making them drive out and try to take off. Kill them all while they are taxiing to the runway; DON'T let them get to the air. Then the mission should end.

I forgot to mention, my recommended aircraft is the F5U Flying Pancake, fully upgraded. Used the Fritz bomb. Tip: to guide the Fritz X, hold your bombing button down, and steer it to the target. You will have a view from the bombs perspective. The max range of this bomb on the F5U is 4000 ft, full speed, 1500 ft in the air.

actually the planes can take off, but you can't let them get too far, I myself have never let them get in the air for more than 10 seconds though.