Baron, we’ve been referring to climb at V minimum drag, approximately final segment climb speed,
and with flat rated engines. That’s why I had put the phrase "same conditions". Certainly a typical
climb to FL 370 is temperature dependent.
Keiths post seems to nail it pretty well. Having read
it a further 7 or 8 times, it now makes even more sense.
The assumption that thrust is "flat rated" does not apply to changes in TAS. Hence while climbing
at V min drag, which is a calibrated air speed, temperature increase causes a measureable loss in
thrust available, for other than pure jets.
Secondly, if I understand him correctly, there is an increase in Power required (note that Thrust required
will stay the same) due to the increase tas as temperature increases.
Third, and I’m not 100% sure of this, (KEITH can you help here) there is an effect on Power
available, as temperature increases, due to the increase tas. (P=T x V). thrust may slightly
decrease due to tas increase as temp rises, but velocity in the formula also has an INCREASE. I
think Keith is saying that the total effect on Power available though is that it decreases.
I’d say the jury is out. Even at V min drag, expect a decrease in the climb gradient
for BARON and HOTDOG,
Do either of you two have a V final segment climb GRADIENT chart, and are you capable of providing
any figures on how much the gradient changes based on temperature?
For simplicity, it looks like Dassault publishes their’s as a straight line, ie no change in climb
gradient with temp, when considering the flat rated portion of engine operation
Does anyone has a link showing Power available, required, and Thrust available, VS velocity,
for different TEMPERATURES?
Many thanks for your efforts