[IvanK]

Voyager said:

"Actually, after reading through all of what I just wrote, I just realized, a balanced fuel system isn't going to induce large CoG shifts as it drains. Does Il-2 even have the capacity to model CoG shifts as the fuel system empties?"

Precisely and at present no, IL2 doesn't vary C of G for fuel burn off.

Which is why comments like the P51 (at present) flies like crap because the C of G with the rear fuselage tank and its incorrect feed schedule are wrong shows a basic lack of understanding of the how the stock IL2 fuel system and C of G model is used. It also shows (imo) a lack of understanding of Pitch stability and the effect of C of G has on it.

One thing IL2 can do is vary C of G dynamically as a function of weapons use. If you want to get a feel for what flying with an Aft C of G in a fighter is like in IL2 then try this.

Jump in the YAK 7B set 25% fuel and 128 Ptabs. This results in a C of G way aft as the PTABS are internally stored aft of the cockpit.
Go for a fly to get a feel for it . Then do a 1 v 1 with a comparable opponent. I think you will agree its not pleasant to fly in this configuration. Drop the PTABS the C of G moves forward to a more respectable position and pitch stability improves dramatically and it becomes a comfortable old Yak again.

The P51 with fuel in the fuselage tank will behave similarly. So if modeling C of G movement as a function of Fuel usage is achieved, and manual fuel tank selection is possible in IL2 (so as was done IRL the Fuselage tank can be selected to feed first) then P51 pitch stability is going to be a whole bunch worse than what you now have in Il2 with fuel in the fuselage tank. As the fuselage tank fuel is burnt pitch stability will return to something close to what we now have in game.

The P51 with fuel in the fuselage tank was not a pleasant aeroplane to fly the various Flight manuals are full of advice like:

RAAF P51 Flight Manual AP780 :
When the fuselage tank is full, the aircraft is longitudinally unstable in all conditions of flight and tends to tighten up in turns .... no maneuvers other than gentle turns should be attempted.

USAAF AAF Manual 51-127-5 (PG 67)
Be especially careful in handling the stick when the fuselage tank contains more than 25 gallons of gas. In this case the flying characteristics of the airplane change considerably....The weight of this fuel shifts the centre of gravity back so the airplane is unsuitable for anything but straight and level flight.

....With the fuselage tank full the centre of gravity of the airplane moves back so far that it is almost impossible to trim the airplane for hands off level flight.