for estimating speed at overrun based on a decision after V1
Depends on a bunch of things, as always ... however, if one considers initiating a reject a little after V1, as for example in the case of startle factor, there will be three stages to consider
(a) the speed/distance overrun. For an AEO reject this will be a modest kt/sec value and, for the OEI case, something lower again. Main result is that the speed increase will normally be comparatively modest but the distance lost which is associated with the delay can be quite significant. For example, for a nominal V1=150kt increasing to, say, 160kt, we are looking at something in the order of 260 feet/sec overrun .. 4 seconds and you have burnt up 1000 ft. As I recall for the 722, a critical reject stopping distance was in the order of 1500-2000 feet or so ? One really can't afford to squander 1000 feet in anger ..
(b) the transition from go to whoa. It is probably reasonable to presume that a well trained pilot, after the startle loss, will go through the motions more or less as per training. For the sake of the argument, let's suppose that this phase is the same for a correct/overspeed initiation.
(c) once the reject is in full swing, the rate of deceleration is quite significant and driven principally by V^2 in the first approximation. What this means, for a critical ASDR runway overrun, is that the end of the expected distance can be crossed at quite a significant speed.
(i) first result is that one IS going to end up in the rough
(ii) second result is that the braking capability is almost certainly going to be significantly less .. ie the net deceleration will decrease .. and the bird ends up some moderate distance off the end of the seal in whatever state of disrepair and in whatever terrain pertains ....
Point is ... accel stop on a critical length bit of seal ... is a VERY critical operation and one had best get it right first time around ... as there is no second chance if that doesn't happen.
Gee whiz guys, I have done V1 cuts in jets for YEARS..over and over, and over...still here.....not so much as a flat spot on the tires.
.. but not on a limiting strip length, I suspect ?