Regardless of what deployment angle the load on flaps could theoretically allow, the real question for a simulation is; was this in-combat deployment actually worthwhile and used in real life? If the answer is no, then it makes sense for a simulation to treat flap deployment as a landing feature only, which could be what the manuals intended to do, discouraging, as Hitech says, an unprofitable use of those flaps.
In the 109 flap deployment video, it clearly shows a few simple turns of the wheel easily reached 10° or more in two-three seconds, with little effort, which is makes it not that unthinkable they could have been used in real life during high speed combat.
Yet we have Stigler on record saying flaps on the 109 were never used in combat. Maybe he meant they were never GAINFULLY used that way, given the non-MW-50 109G/K's poor speed retention in turns, but in any case that statement carries greater weight for me than what could theoretically be done with those flaps, especially since MW-50 use was not so common "in the field".
In a simulation, what I would then do is avoid offering a MW-50 equipped 109 model, since much less is known about it... It could be that those DID find it competitive to use flaps, accounting for their apparently greater turn performance... We may never know, but I'll add MW-50 did blow-up engines in dives, or burn them in climbs, with alarming regularity...
A trick we DO know was WIDELY used by the 109G was trimming the aircraft very tail-heavy, so that a constant push was required on the stick just to fly level. This allowed a much faster nose-up response when suddenly pulling the stick at higher speeds, elliminating the 109G/K's high speed mushing-delayed elevator response (Osprey BF-109F/G/K aces of the Western Front).
When was the last time you heard THAT trick being used on the 109G in a simulation game? Yet it was widely taught in Luftwaffe training, and was widely used, as apparently evidenced by the common observation by Allied pilots that a lot of the inexperienced 109G pilots tended to "Gear" up and down as they they tried to fly straight...
Quote, Hitech: "3. Make some assumptions and guesses that different methodologies were used when writting manuals, and then try to model all flaps as if the manuals were all written with the same mythology."
I think WWII comparative flight modeling IS guessing, regardless of what anyone claims about it. There are just too many dark holes for it to be tought of as "scientific", or to follow rigidly a methodology accross unrelated evaluations and manuals that may have had different criterias or purposes.
The best example of what not to do is applying math uniformly to the FW-190A's low-speed turn rate, ignore what virtually everybody in the Luftwaffe and elsewhere has said about it, and then say the non-MW-50 Me-109G or K out-turns it at low speeds by a significant margin, or that it (the FW-190A) is a great high speed (or even vertical!) fighter... By trying to be too "scientific", you get the exact opposite of reality...
Gaston
