Not that myth again. It's disappointing to have to point out to one who calls himself an instructor that in your 'brakes on' scenario the aircraft is still producing 200 THP as well as 200 BHP because it is accelerating a mass of air rearwards in a futile attempt to turn the earth and the atmosphere in opposite directions. Come on italia, pull your socks up. These are fundamentals that instructors should have a grip on.
Very quick to throw the insults out. Yes, I am a flight instructor. Here is today's lesson:
When talking about performance, the paragraph below is appropriate.
"Power is the rate of doing work, and work is a force times a distance. Power required (
PR) is the amount of power that is required to produce thrust required.
PR is the product of TR and velocity (V). If V is expressed in knots, then the product of TR and V must be divided by 325 to give power in units of horsepower. Thus, thrust horsepower only depends on thrust and velocity."
If you're talking about propeller efficiency, the paragraph below is appropriate.
"In a turboprop, power available is determined by the performance of the engine/propeller combination. Engine output is called shaft horsepower (SHP). Thrust horsepower (THP) is propeller output, or the power that is converted to usable thrust by the propeller. The ability of the propeller to turn engine output into thrust is given by its propeller efficiency (p.e.). Under ideal conditions, SHP would equal THP, but due to friction in the gearbox and propeller drag, THP is always less than SHP. Propeller efficiency is always less than 100%."
So, with regard to your statements:
He is talking about the fact that if the RPM is stable, then that is because thrust horsepower equals brake horsepower at that moment in time.
...the aircraft is still producing 200 THP as well as 200 BHP...
THP will never equal SHP or BHP.
Those two paragraph quotes were taken directly from the "Fundamentals of Aerodynamics" which was prepared by the U.S. Naval Aviation Schools Command.
EDIT: Here is a picture taken from the same textbook.
imgur: the simple image sharer