Fuel tank loadout is different.
In AH1 if you selected 75% you got 75% in all tanks ie main and both wing tanks. Repeat for 50% and 25%.
In latest beta for example if you select 50% fuel loadout you now get 75% in the main tank and no fuel in wing tanks which become unselectable.
Stall speeds are lower with flaps considerably so.
I intended to film a test then view it and note the speeds, unfortunately the film viewer is borked again.
So from memory 50% fuel, power on, gear up, no flaps stall speed is approx 95 mph and with full flaps approx 65-70mph.
And if you push for the stall it will rapidly drop a wing.
The F4U-1D however stalls full flaps at approx 80mph again with 50% fuel but of course its a lighter load than the -1's.