I haven't done much with the FM's yet. I tried a couple of FM's that came with some of the models but most cause immediate CTD's when trying to play or else the numbers are far off. For example, I has the thrilling experiences of a 280 MPH Sopwith Camel......unfortunately the modder has also edited the damage data so after about 15 seconds the wings tore off.
I have some pretty good WW 2 biplane FM's that I can use to fashion new FM's for the WW 1 planes. The big issue was the slow speeds that the planes run at but I was able to manipulate some of the data points to get some good results. The only one I'm not sure about is the Zepplin but I'll probably be able to make it work as a target, not as a flyable choice. I mean, who wants to cruise around with a giant bag of Hydrogen directly over your head anyway.
I will package up the Allied models and send them up to the server later today so you can take a look at what I've done.