777 rotate angle

[michaela74]

Hi folks,
What is the body angle a 777 or a 787 registers a rotate during take off? It states in the books that if the aircraft is rotated too slowly then target speed during initial climb will be rotate speed up to V2+ 25 instead of V2+15. But what is the aircraft using to register a rotate and where can I find that info. Thanks.

[rudestuff]

The target is V2+15. If you rotate slowly then you'll naturally blow past that. As you do the flight directors will command that higher speed, but only up to a max of V2+25. (My understanding is that) the rate of rotation is irrelevant, the speed you get to during rotation is what determines whether you end up climbing out at V2+15, V2+25 or somewhere in between.

So it doesn't "register a rotate", other than weight off wheels registering a takeoff - it registers airspeed, and you can find that info on the Airspeed Indicator. 😜

[wiggy]

If I remember it correctly the guidance used to be rotate towards a 15 degree nose up attitude, then follow the flight director after liftoff..so depending on circumstances and for the sorts of reasons given by rudestuff you might not actually end up at 15 degrees.

[EXDAC]

The OP may find tail strike pitch attitude to be the limiting factor during rotation. What happens after the aircraft is clear of the runway depends on target airspeed and any pitch limiting included in the design. For the types I worked on V2+10 was the nominal target but that was often pitch limited. Test pilots on MD-11 were not comfortable with the over 25 deg pitch attitude needed to fly V2+10 at lighter weights. I think we settled on 23 degrees as the maximum pitch the FD would command.

[Jack D]

Rotate at 2 deg per sec in 77 ER or -300, (2.5 in smaller variants,) towards 15 deg initially.
Adjust pitch accordingly to achieve V2 + 15 - 25 kts all engines operating.
The main point is to achieve the correct rotation rate to avoid a tail strike and not fixate too soon on IAS. Aiming for 5 seconds as pitch passes 10 deg anu will avoid tail contact with the rwy during rotation