I'm sorry formulaben, but I don't agree.
VMCA is a MINIMUM controll speed, i.e. the speed above which you are certain during flight that you can maintain directional controll during an engine failure.To establish this minimum number, the manufacturer takes a worst case scenario, i.e. configuration just after t/o, and then sees at what speed you can no longer maintain direction. This configuration has been given above. This means that for a given type the VMCA
is always the same. However, given your configuration and flight profile, it is possible that you are able to maintain direction at a
lower speed, but that is not what the definition is about.
The rest of the story goes for a light twin prop, where a big part of the lift is generated by the propwash. If you would have flaps set for t/o, and you would have an engine failure, this would mean that the wing with the working engine
and the flaps down, would give you more lift than without the flaps. Therefore the speed to maintain direction would theoretically be higher with flaps than without, therefore the flaps in t/o position requirement.
As seen before, if this difference is really noticable, remains the question, but this would be the theoretical approach.
I hope you can all live with this explanation, if not, just fire at will
