This is all well and good, but what about the practicalities?
Let's take a Bulldog for example, an above average performance trainer with a Vr of 45kias (POH), but an ASI bottom stop at 40kias, which is 89.8888% of VR.
So this aeroplane could never comply with Slim Slag's rule of being at 71% (or 75%) of Vr, because the ASI is not capable of reporting this.
If we apply Slim Slag's thinking, we would either take off because we got to 89.888% of Vr on a runway long enough to allow this before 1/2 way or we would would have to reject the take off, even though we might be between 71 and 89.7% of Vr.
This sounds a bit silly to me.
What is wrong with looking at the POH, calculating the performance, safety factoring by whichever method we choose and then picking a spot where we expect a certain performance, rather than starting out with a highly generalised premise, which as I have just proved, cannot work in a well respected light aircraft?
Last edited by Final, 3 Greens; 25th January 2003 at 15:53.