Ok, I was harsh and apologize. But I do get very tired of 'You Americans only do things if America wins'
My friend if you start a discussion like that, you're looking for a fight, consider your own words in relation to my response.
Anyhow, returning to your thoughts about Z, its absurd, and here is why...
I'm zipping along at 400 mph horizontal. I pull into a vertical climb and now I get to go 800 mph?
How ridiculous would that be? Have you considered that?
You sure put on a show like you know what you're talking about, but have you considered how inertia is supposed to be modeled in your new scheme? An objects inertia at 800 mph is not simply doubled. So now that I've got my 800mph climb going, it's going to take a while for it to burn off. More than double the time. Speaking of inertia, what about manuvering? If I so much as twitch the stick I'm gonna black out.
And if I go back to straight and level do I magically return to 1/2 of my vertical speed?
Let's try to apply some common sense here. Fuel burn is a constant value for a given throttle setting. It's a simple solution to a flight world that is a lot smaller than the real one.