I thought this might have come to an end when I agreed to disagree, but ok, let's continue!
You're doubtless familiar with the story of the man who bought two horses named Arnie and Sam, and took them back to his farm
I wasn't, but I am now. It's a good analagy - and it makes my point very well.
If I wanted to buy a show-horse, I would go to the horse dealer and ask if I could buy a Lipizzan. I'd then get what I wanted. If I simply asked him for a horse, I'd quite likely come away with the wrong type of horse - unless he sought further clarification. The word "horse" works perfectly well in many circumstances, but is too ambiguous to be of any use when I'm at the horse dealer telling him what I want to buy.
"Vmc" is exactly the same as "horse". It is often perfectly acceptable to use it, either because it doesn't matter exactly what Vmc we are talking about (rare), or because the context provides clarification (more common). But it can also be ambiguous.
Let me ask you some questions:
a) What happens to the control of the aircraft at Vmc?
b) Can you explain why Vmc is lower when 5 degrees of bank towards the live engine is used compared to when the wings are level
c) Does Vmc change with height?
In question a, it doesn't matter which Vmc we are talking about, because the answer is the same regardless: the answer is that control is lost.
In question b, the context tells us that we can't be refering to Vmca, we must be talking about the actual speed at which control is lost. If we were talking about Vmca, the question would be nonsense because Vmca is defined as not being wings level, but the question asks about Vmc with wings level and implies that Vmc exists, and is different, if wings are level.
In both of these cases, the phrase "Vmc" is absolutely adequate.
But in question c, it is not. The answer to the question depends on what Vmc we are talking about. If we were being asked about Vmca, we might answer "No, Vmca is always quoted for sea level". If we were being asked about the actual speed where control is lost, we might answer "Yes, Vmc decreases with height in an aircraft with normally-aspirated engines because the good engine produces less power the higher it is."
So, in the case of question c, the phrase "Vmc" is ambiguous.
I think it's more that you either disbelieve the concept here, or don't understand it.
I believe the concept thanks to your quotes, and I understand it perfectly. Just because what you are saying is factually correct, that doesn't mean I have to think it's a good idea!
FFF
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