Originally Posted by
Dutch M
@henra
Hmmm, headwind, tailwind, airspeed, groundspeed ?
And yes, the speed bleed-off is limited by the aerodynamics to keep the airplane flying. Though speed bleed-off is not the same as loss in inertial Ekin.
Hmm, I don't want to sound rude, but did you really understand my example ?
And yes, the square of the speed before the bleed minus the square of the speed after the bleed is exactly the kinetic energy you can trade for altitude.
What is speed bleed if not redution of kinetic energy ???
Edit:
You really need to understand the concept of reference systems to get a grip on this.
Let me ask:
What do you think is the kinetic energy of the aircraft in my example after the speed loss of 100kts?
Please note: It is flying backwards now. Does that mean it has a negativ kinetic energy by now ?
Other question: Would the aircraft care if mother Earth instantly decided to change its sense of rotation by 180° from one second to the next?
You probably guessed it: It wouldn't give a sh't as long as the air around it keeps moving unchanged. The only force which the Earth itself applies to the aircraft is gravity and that is vertical.
Edit3:
Yes you can calculate the total kinetic energy of the AC with regard to the sun but that would be absolutely pointless. You can also calculate the kinetic energy with regard to the ground but for the question of how much altitude can I gain by giving up airspeed it is also irrelevant. It is only speed through the air which I can trade. When speed through the air is Zero there is excactly 0kts to trade. You can't get 'slower' than 0kts TAS/IAS/CAS. No matter what the surface below does. Or how the sun turns around this point.