Well it is possible to win the campaign as the americans (im sure some of you already have done this)... it was very difficult however and the war went into the end of april 1946.
My pilot is a Major General and the aircraft is a P-80 Squadron aircraft and a P-55 personal aircraft.
France was entirely liberated from border to border with the front line extending into the mediteranian and outlining Italy, spain and switzerland. The eastern side of the front found its way as far as berlin where it stopped and the war finally ended.
I used the same basic strategy as i did with the British campaign however the front line was much slower to advance. Playing as the British i faced only a handful of fighters however as the americans it seemed like i was getting jumped every other mission. The most advanced german fighters i managed to go up against were the Do-335 and the 262 i never saw the Gotha however. (Most of the Do 335s never got a shot off)
I found the P-55 to be a far superior fighter when compared to the P-80 and actually chose to use it on nearly every mission. The roll rate of this plane is equal to or better than that of the FW-190 especially at a speed range around 250 to 275 Mph. One must be careful when dive bombing to not let the speed accelerate past 400 Mph due to the loss of effectiveness of the canard wings... recovering from dive becomes increasingly difficult above this speed. cornering above 400 - 450 Mph is a pain as well.
The key to succes as the allies is to concentrate on Close air support and use ground offensives sparingly instead use the prestige points to upgrade your squadron.
I suppose the same strategy works for the German campaign but i never managed to make the war last long enough flying for the Germans to even get out of the FW-190! This game is far too easy for the axis players.