Hi, baggy, knold, cough, boac, m+v and anybody else interested in the V1/Vr,
I have done some deep book diving and came out with a conclusion. I quote from the 737 AOM:
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For reduced thrust takeoffs based on assumed temperature, determine V1, Vr and V2 using airport pressure altitude and assumed temperature.
Adjust V1 for slope, wind clearway and stopway.
Compare adjusted V1 with minimum Vmcg from table using airport altitude and actual temperature. This is to cover the case where the pilots elects to advace the thrust levers to max take off thrust.
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Vmcg (min ground control speed) is related with the thrust the engine is developing. If it is at high thrust, as in low temperature and low elevation (low DA Density Altitude) we need a higher speed to counteract the assymetry.
But this is all I know.
¿why increase V1 and Vr when derrating?
¿is it to operate in a balanced field?
anybody is welcome to check his/her Operating Manual and compare the results
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vuela bajo y despacio me dice siempre mi abuela.