Originally Posted by
airtren
One of the AF 447 BEA reports indicates a TAS of 461 knots at FL350, while yours is 495 knots.
I used the factor of 1,8 (1,798) for standard ISA conditions at 35kft.
Differences to that standard factor may result from temperature differences.
Please note: the BEA value was GS. The calculated one would be speed through the air corrected by density effect. Therefore also a headwind could be a possible explanation for the difference.
Even further, and more importantly, you're indicating a calculated "delta h" based on the two TAS of 495 and 390, of 4200 ft, and you're reasoning that the larger "height" value (of 4200ft versus 2500ft, a difference of 1700ft) is explicable by the increased drag during the ascent/climb.
Maybe I was unclear or maybe I#m misunderstanding where you are coming from.
What I was trying to point out is the fact that any additonal maneuvering (pulling g, thereby increasing induced drag and worse cl/cd of the wing or rolling, thereby increasing drag coefficient due to moving surfaces and induced drag due to resulting g load) will consume kinetic energy thereby reducing the amount which can be converted into altitude for a given speed.
On the other hand flying at 250kts IAS will require less thrust for 1g level flight than 275kts. So after slowing down and leveling off the engines have some excess thrust which would contribute positively to the energy available.
As takata has pointed out that is only partly true as below a certain speed the drag will rise again due to ending up in a less good cl/cd area (higher Alpha) of the wing polar. So at the end you can probably leave excess thrust largely out of the equation.
Based on the BEA text, we know 275 knots (FL350), and 211 knots (FL375), were speeds that resulted from Real Time measurements (and/or calculations based on Real Time measurements).
For an exact determination of TAS we would need the Air temperature as well.
Pointing out, or explaining that a calculated approx 4200 ft height's discrepancy of 1700ft is due to Drag, or Thrust, means including Drag or Thrust a second time in the equation. That does not seem to be correct.
What I was trying to explain is that I estimate that additional drag resulting from maneuvering (pulling g, rolling) could be sufficient to consume the 1700 ft worth of energy.
There are two effects impacting on the drag: even infinte wings used for calculating airfoil qualities have their best cl/cd usually at low AoA. Increasing AoA will deteriorate this ratio. On top of that increasing g will addiotionally increase the induced drag.
Unfortuantely without exact cl/cd curves for the A330 wing it will not be really possible to calculate the net energy loss due to the initial pull up.