Originally Posted by
Brercrow
No No No You are talking about a person in an aircraft. The person walks toward the tail at 1 kt turns around and walks towards the nose at 1kt. But relative to the ground he is still moving with the aircraft
Scenario A (Cessna)
final groundspeed minus initial groundspeed
(airspeed + tailwind) - (airspeed - headwind)
(100+10)-(100-10)
110-90
20
Scenario B (Person inside airliner)
final groundspeed minus initial groundspeed
(airspeed + tailwind) - (airspeed - headwind)
or, if you like:
(walk + tailwind) - (walk - headwind)
(1+500)-(1-500)
501-(-499)
1000
You're not understanding the analogy. I thought I was clear enough in being excessively verbose and redundant in all the details. The airmass inside the moving airliner (scenario B) represents the airmass that is the steady, uniform wind the Cessna is flying in (scenario A)
The airspeed of the person walking (1 knot in scenario B) represents the airspeed of the Cessna (100 knots in scenario A). It's the speed of the person moving relative to the airmass inside the airliner. Like the speed of the Cessna relative to the airmass it's flying in.
The "airspeed" of the airliner in scenario B (500 knots) is not analogous to the airspeed of the Cessna (it's only a coincidence in the use of the same word.) It is analogous to the wind speed in scenario A (10 knots). It is the speed of the airmass over the ground.
Your rearranging of the terms is incorrect. Please look up and read it again, while keeping straight what is analogous to what. Line by line, term by term, I really don't know how to make it more explicit. Examine it again.