Hi Gysbreght,
I did. Can you explain that graph to me?
Please have a look at Page 7.3, Eq 7.7 "Climb correction factor" (CCF)
http://www.aviation.org.uk/docs/flig...-FTM108/c7.pdf
If the aircraft was flown at constant TAS then Keith Williams equation
Climb gradient = 100% x ( (Thrust – Drag) / Weight)………Equation 1
would hold true.
Since we fly a constant IAS during the climb, then TAS is increasing and there is an additional Kinetic Energy contribution which needs to be considered and appears as a CCF.
i.e. If we gained X% TAS during the climb, then the incremental increase in TAS is greater when the initial TAS is bigger (when the temperature is warmer). The additional KE is proportional to TAS squared, so the CCF is further away from unity when it is warmer, hence the climb gradient is less.
Edit, How many can remember density being expressed as:
ρssl (rho) Standard sea level air density = 0.0023769 slug/ft3 ?