Originally Posted by
lomapaseo
I would discount the locked fan scenario as not realistic or valid.
The drag characteristics are set by the inlet frontal area and not the engine fan where the spaces between blades are great enough to let the air out the by-pass. Engine spillage effects are only temporary in nature and typically associated with engine surge.
All this not withstanding flight simulator training.
I agree, locjked fans are unlikely. But the scenario being postulated - the need for a crew to increase thrust above that planned to achieve the regulated takeoff performance - is itself an inherently unlikely scenario. 9.9...% of the time there will be no need to even exercise the reasoning being discussed in this thread - leave the thrust where it is and everything just happens by the book.
My point was to highlight that the same kind of scenario where you may have a need for excess thrust over the planned level may also have consequences for other aspects of the aircraft, such as handling, and all would need to be considered before pushing the levers up.
I know of one engine failure event where, due to the nature of the failure, the aircraft was barely able to sustain an altitude which was some 10,000ft below the advertised single engine capability. It all came down to much greater drag from the failed engine than for the assumed windmilling case. If that had occurred on takeoff, the considerations I mentioned would have applied - and I suspect it might not have been survivable, even with firewalling the engines being an option.