lbetter actual acceleration lift changes with acceleration=more lift with given unit time/distance-- the wings are working at a lower pressure altitude because the temp is only 'assumed' for the engines, but the engineers don't take that benefit in account and it gives a margin---
-- The engineers don't take it into account because it doesn't exist as a benefit.....so using your logic...the slower we go (flex acceleration)the more lift with a given time/distance? lol..even so...ok I will bite....you said 'benefit'..how does this BENEFIT...flex doesn't make us go faster, but slower, it doesn't reduce runway length but increases it, less initial air over the wings.=.less active control imputs and feedback along the runway untill later in the roll, less time to find out of an aerodynamic problem exists...we know Flex uses more fuel as well...so what are you saying...that we create more lift flying slower....or that flex, somewhere in the box, some computer program creats a force field of extra lifting energy at slower speeds...
And better stopping [before V1]with reverse becasue you get full rated RT [that's why it unofficial because in part 25 dry RT doesn't exist,]also spoilers and retardation devices are better in the denser air
- So flex power changes the air density around the aircraft, helping spoilers and retardation devices So flex causes a FORCE FIELD? around the aircraft to create denser air over the spoilers and retardation devices?