Is it correct to assume that 180W*75%= 135W of power at the shaft and 45W given off as heat?

Would the same be true for RPM or kv?

1400kv*11.1v= 15,540RPM

15,540RPM*75% = 11,655RPM

I don't think it works like that, not to mention all these numbers are dynamic while in flight, and which prop are you using? lol

Physics, just isn't as cut and dry as that. If that stuff interests you, you need some advanced electrical and aerodynamic books, I am not even going to pretend to understand the math behind what you are talking about but I bet there's many interacting equations and dynamic answers or even subjective answers, like how fast is the airplane moving when you measure this? What is the ambient temperature and what is the air pressure... do you even know at what RPM, temp, resistance (prop) voltage that 75% number came from? How can you trust it?

My personal view of the subject goes like this. I just know and realize that the power systems are not 100% efficient. Some more than others. That is why it is so important for us to get all the numbers right where we can so we are not hurting the efficiency further. We will never reach 100%, but there is a peak to every system and it is usually adjusted and found by using the proper propeller...The airplane should be designed around the prop, and the power system should be designed to spin that prop at it's max efficiency...call it simple if you want, it's actually quite complex...

Best way to do this is to change props and test, change props and test, change props and test...just make sure you have a pile of props, a notebook to record all the numbers and a watt meter to read them. This is all you need to reach the max efficiency of a power system..

And most of the time, you will find that the manufactures recommendations, are spot on...