francoflier From France, joined Oct 2001, 3514 posts, RR: 11 Reply 1, posted (2 months 3 weeks 4 hours ago) and read 3479 times:
That's a strange feature, if it is actually one.
I can't see why they would feel the need to have the doors open during rotation, as that creates extra drag during a critical part of an engine-out takeoff (though it could help with directional stability).
It would allow for a faster gear retraction, thus helping slightly with the second and subsequent segments, but it seems a rather peculiar thing to do unless the a/c was performance limited in the second segment.
Looks like I picked the wrong week to quit posting...
bellancacf From United States of America, joined May 2011, 139 posts, RR: 0 Reply 5, posted (2 months 2 weeks 1 day 16 hours ago) and read 2093 times:
Perhaps opening the main gear doors at a significant angle of attack involves countering significant pressure from onrushing air and spikes the current draw; the 787 being a heavily monitored electric beast, someone probably noticed and then wondered how to avoid that spike. Opening them while on the runway (before rotation) would eliminate this hypothetical spike (door's straight generating line -- speaking geometrically -- in line with airflow). Anyway, that was my first reaction to seeing them open early.