Re: Derate and V-speeds
Without derate, V2 is way below VL/D MAX. This is possible because the aircraft has so much power that flying at such a slow speed does not compromise performance.
When you derate, the performance edge is used to achieve a lower N1 & - most important - EGT during take-off. Now the aircraft needs a V2 that is a lot closer to VL/D MAX to meet the climb requirements. And since V2 needs to go up, up goes V1 and Vr as well.
Besides, I do remember something about the speed for max excess thrust increasing as thrust decreases - which just further adds to the requirement for increased speed.
Hope this helps - best regrads fm
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