Re: Derate and V-speeds
If for exactly the same weights and conditions, you reduced the takeoff power by 10% (for example), some of the other variables have to change.
Calculating a Balanced Field Distance for the B777, 35C and 250,000 kgs, the 1 engine accelerate stop distance will increase from 8506 feet to 9413 feet.
Once this happens, the V-speeds will also change, the resulting V1 will change from 147.9 KIAS to 151.2 KIAS.
So in reality, you arent comparing apples with apples due to the change in the runway length required.
Mutt