av8r76 & quid
May I try to put it in a nutshell
It’s easier to explain when you reason it out backwards
V2 = 1.2 Vs
Vr must be such as to reach V2 at the latest at 35 ft and above the runway end in the balanced case.
So the bigger the difference between V1 and Vr (the one engine acceleration part) the more runway you need, hence the reason to increase V1 closer to Vr (it accelerates better with two then one) as long as there is enough runway left to stop at this increased V1.
V2 depends only on weight when expressed in EAS (and IAS=EAS in the low range of speeds and density altitudes)
So if weight goes up, V2 goes up, so Vr goes up and hence V1 goes up if enough runway is left over otherwise the weight can not go up and you have reached the maximum for that runway.
I know there are some factors as Vmu, Vmca ,Vmcg Vmbe involved as well but these do not affect the aforementioned principle of reasoning to a large extend if we concentrate on the original question "How does weight influanse V1" or am I overlooking something here ?
I know that V1 has some upper and lower limits dictated by brake energy, tyre speed and Vmcg but thats besides the original question I think ?
But do you agree with the following?
In the case of balanced Take Off we set TOD = TOR as a condition for the calculations.
If you want to squeeze out a bit more performance you can go unbalanced and use clear and stop-way to a larger extend.
As far as I know balanced or not has nothing to do with the practical or theoretical concept they are both theoretical but any feedback on this is welcome.
------------------
Smooth Trimmer
[This message has been edited by Streamline (edited 28 September 2000).]