Hi Hazel
Now draw another tangent to your curve from a point at 10 kt on the x-axis. The point where the second tangent touches your curve is the airspeed for max angle of climb in a 10 kt headwind.
OK let's imagine this ( Still Air graph ) is actual and correct.
Tangent on a curve ( 0.15) ~Airspeed 100. No wind. We get V/S ~ 8 m/s
If we have 20 m/s head wind the Gradient is 8/80=
10 %
What you suggest is to add wind to this “still air” graph. Hence move zero to right by 20.
Then tangent on a curve ( 0.15) ~Airspeed 90. Now we get V/S ~ 7 m/s
So now we fly 90 m/s with 20 m/s head wind the Gradient is 7/70=
10 %
Other curves similar thing. And where we put tangent for a 60 kts wind ?
Also if you have a tailwind, would you increase the speed for better gradient ? !!!
All other arguments about 90 deg vertical climb actually do not care about Vertical Speed.
Even with V/S is as low as 1 ft/min ( 5 mm/sec) who cares about obstacles ?