Suggestion.
HT, the flak. Not only do a lotta people complain it's uber, unrealistic and generally a pain in the backside......but it looks pretty awful too.
I heard the other day about how you cant model each individual shell (major frame rate hit) and that's why flak doesnt have any tracking delay when firing to 20k. Ok, so that's out. But how bout this:
Forget single flaks, put in flak battery's of 20 or so. Fire link them all together and model one area of sky that takes all the fire. Then make your flak explosions MUCH less damaging. If it's possible, have the flak begin a few hundred yards in front of an incomming aircraft and hold there, firing at the same bit of sky until the plane flies through it, then begin tracking. This gives a fighter a chance to get outta the way......and would look seriously cool to a buff pilot about to fly into a *wall* of flak.
More flak, less damaging.
For a really good example, go buy a copy of B17.