I am still trying to get my head around the graphs, to be honest. But I have been reading about something like this before too, where they stated that if you you was not FLL, than V1 would increase with mass, as we both agree on.
Same place I read that if FLL, than by reducing mass you would also be able to increase your V1 - I can't find this "book" or article where I read about this now, where I can find all the details about this.
But would this than be an unbalanced V1?
My logic behind the reducing the mass theory, was that you would be able to increase V1 - (with sufficient mass reduced), so that you would reach this higher V1 earlier. (as F = m x a which would be: a = F/m)
In my mind, I might be wrong, but this was my own theory behind it, you accelerate faster to a higher V1, because you have less mass, this means even though you have increased your V1, you will reach it at an earlier stage on the runway, because you are faster now.
You will also need a longer ASDR, but because you are lighter, there will be less inertia, to make you stop faster, although the balance between higher speed and less mass, will have be done trough performance operations/calculations.
Are these assumptions and logic above completely wrong? Or is there some major issue that I am failing to see with this?
The main reason I see that V1 increases with mass, when you are not field limited, is that you must have sufficient speed to be able to continue your take off, VR will increase with mass.
That means if you are very heavy, the gap between V1 and VR will most likely increase. So increasing V1, is to ensure that you can reach VR with one engine inop before end of runway. Which if the gap is to big, you might not reach, so you can than reduce VR by reducing mass!
If V1 is less than Vmcg, that means you reach V1, you will not be able to take off, but the only way I see from logic, is to make V1 equal to Vmcg. But obviously those calculations will be have been based on your current performance calculations.
Please I apologise if for what I have said, if I have completely missed the target here on this, but for me it did seemed logical way to explain, how that reducing mass would be able to increase your V1! And I would have thought there would be a mass that would still keep you within the balanced field requirement.
Your V1 must be high enough to stop and go, if you want to increase your V1 to a higher speed, you must find a way to reach that speed within a shorter distance than your older "to low V1", because as your V1 will be higher, you will need more distance to stop too.
So for me the logical conclusion that you can reach a faster V1 at a shorter distance, is to increase your acceleration, and to do this you must reduce mass, as Thrust / Mass = Acceleration