Can anyone explain to me why the inboard ailerons on the 777 cycle through their range of travel during the first part of the takeoff roll?
As the engines stabilise, both ailerons droop. As the aircraft accelerates they slowly retract until they are flush with the wing's camber. This is maintained for short time before they return to their original position (flush with the trailing edge flaps).
You'll see an example of what I'm referring to in this video
Initially, I thought it might be due to control column input for a crosswind. But the ailerons cycle through this same movement on every takeoff.
What purpose does it serve?
Many thanks!