Allow me to explain the meaning of the graph.
On the ingame UI:
Stall speed for the Spit I is at 120 km/h.
Yellow speed is from 130km/h to 170 km/h.
White speed is from 170km/h to 400km/h.
Speed then goes to yellow again from 400km/h to 600km/h.
Red again from 600km/h to 680km/h.
What the graph shows is the time it takes to complete a full level 360 degree turn at a specific speed.
And what you get is something quite different from how it used to be.
Here's an outdated graph showing the same variables.
http://forum.worldofwarplanes.eu/index.php?/topic/18947-thrust-and-extended-flaps/

As you can see, turning time got significantly worse the slower you go. Which, makes sense. You're going slower which means you will take more time to complete the turn.
However, take a look at this turn radius graph.

Turning radius stays consistent below 300km/h because the longer turning time, and the smaller circumference of the turn you should get from going slower cancel out.
Have a look at a turn radius graph for 2.0

Your best turn is literally at 170km/h. Because the turn time stays the same, and therefore your circumference becomes smaller.
If this isn't different flight physics than I don't know what is.
Edited by mnbv_fockewulfe, 19 December 2017 - 03:45 AM.