I thought fowlers were a big deal because they were much better aerodynamically: that they better conformed to the ideal shape for flaps? IE extra lift with less drag compared to split flaps that are just plain dirty, plain flaps that comparatively bend the foil shape too abruptly... and slotted flaps only marginally better than plain flaps? So would a slotted flap and fowler flap of equal surface areas be only marginally different, in effectiveness? Is the slotted flap usually worse in the game only because they're smaller than the typical in-game fowler?
So the 152H's flaps are that much more efficient because of their aspect ratio.. This is the same general dynamic that makes the 152H wing better for E retention in instantaneous turns?
Think of plain, slotted, and fowler flaps as different tools the designer has to work with. The purpose of flaps is to better configure the aircraft for landing--don't think of them in any other fashion.
Next, planes stall at Clmax, and landing speeds are usually a function of stall speed (Vs). Typically, landing speed is 1.2-1.3 X Vs.
Now, from my formula I posted in the previous post, you can see that Clmax = wingloading / dynamic pressure. We know that all wings stall at a given angle-of-attack. If a designer is trying to hit a specified landing speed (say, Vought when they designed the Corsair to conform with the Navy spec on carrier landing speeds), he can either increase the wing area or Clmax, or decrease the weight of the aircraft in order to hit that target landing speed. If you increase the wing area, stall speed decreases, and thus landing speed is lower. But, if you increase wing area, you add weight and drag. If the designers considers changing the airfoil to increase Clmax, stall speed decreases, and thus the landing speed decreases. But, changing the airfoil may decrease top speed due to it being optimized for more high-lift conditions. The designer could then consider reducing the weight of the aircraft, but to do so, a host of other tradeoffs would be required. So, the designer is stuck. Flaps provide him/her with an answer to the problem.
Now, each aircraft only has a fixed amount of wing that can be "flapped"--basically the limit is the distance between the inboard end of the aileron and the wing root. Some aircraft, such as the P-38, introduce another portion of the wing that can't be "flapped". So, he/she has a fixed length of the wing with which to place the flaps. So, now he's determined how long the flaps can be, and has considered how much he needs to reduce the landing speed. So, with this knowledge, he begins to analyze which type and size of flaps will help him achieve his specified landing speed. Plain flaps are the simplest, have the lightest installed weight (typically) but are the least efficient. Slotted are more efficient, but add mechanical complexity and more weight. Fowlers are the most mechanically complex, heaviest, but are the most efficient per foot of flapped area, since the increased wing area and increased camber combine to make them very effective per foot of flapped area. So, you could rationalize that if the flapped area of the wing is restricted (say on the P-38 for example), Fowlers could be a good solution since the extra weight and mechanical complexity would be lessened (due to fewer feet of flapped area), and the aerodynamic benefits maximized. However, on a plane that doesn't limit the flapped area, a designer may be able to achieve a sufficient reduction in landing speed with plain or slotted flaps, avoiding the extra complexity and weight. Obviously if weight and complexity aren't an issue (which would occur very rarely in aircraft design), Fowlers would be ideal. But, since everything in aircraft design is a tradeoff, sometimes good-enough, is.
To truly determine which flaps are "best" between dissimilar aircraft, you'd need to test each aircraft without flaps and with full flaps, then compare which one provides the highest reduction in landing speed using some sort of metric, like percent of reduction, or something like that. I would bet my lunch money that there are aircraft in-game that have more efficient plain or slotted flaps than the Fowlers on the P-38. I could be wrong, and we wouldn't know unless we tested them, but plain or slotted flaps, given the proper application, have every chance to be as or more efficient than Fowler flaps, based on the design criteria of the flap system. If Fowlers are too heavy, then obviously plain or slotted would be "better". If Fowlers are too complex or too costly, then plain or slotted could be "better". I keep emphasizing "better" because its all about the design principles and tradeoffs made in order to give the aircraft the desired landing speed characteristics.
Yes, all things being equal, Fowlers have more potential than plain or slotted, but sometimes the less-complex system is more "efficient"
And, as far as the Ta-152 goes... That testing was done with flaps up, so no conclusion can be made regarding the higher aspect ratio and flap efficiency. You can, however, deduce that the increased wing span helps reduce the induced drag coefficient.