From what I recall, the armour was as bad on it as the B-24.
If a B-24's #3 engine catchs fire or goes out, your gonna go down because you lost hydraulic pressure (and electricity I think)
something wierd happened to me before in the game, i was bomging a HQ in a B-24, and on my way back tol the base ,a ME-163 came in on, i was at about 17,000 feet up, anyways, i shoot him down, but before he go down he shoots 2 engines on fire, so i thinking maybe if i climb they will go out, i climb to 19-20 k and the fire go out, i dont know what happen, if it was a glich or something that HTC has set, but whatever it was it saved me