I thought V1 was independant from Vr/V2
This is not the way I was taught it.
V1 could, theoretically, be any speed between Vgo (the slowest speed at which you can go on a single engine) and Vstop (the fastest speed at which you can stop). Normally, you'd pick a number in the middle.
However, there are certain other speeds which V1 is not allowed to be either more than or less than. For example, it must be less than Vmbe, but it must be more than Vmca. If your initial attempt at finding V1 falls outside any of these restrictions, then you must move it - although it must still be between Vstop and Vgo (if you can't satisfy this, then you have to lose some weight).
In the case where your initial attempt at finding a V1 gives you a number which is greater than Vr, then you reduce V1, such that V1=Vr.
At least, that's the way I remember it being taught...
FFF
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