Defining Approach Speed for Minimum Runway Length
MFS and TA - thanks for your comments regarding landing performance. Are you aware of how consideration of the touchdown attitude vs. touchdown speed sweet spot works its way into Vref or other parameters that serve to have flight crews landing at the optimal point?
I have always understood Vref to be based on a margin to stall and approach speeds to be determined starting with Vref. I know that probability of landing tail strike is also a consideration.
I have not run the numbers yet, but I am guessing that landing with the nose 2 deg lower would take a speed increase of at least 10 knots. If derotation rate is 2 deg/sec, the slower landing at higher attitude would lead to 1 sec longer derotation which works out to about 250 feet at typical transport max landing weight touchdown speeds. Slowing 10 knots in 1 second means about 15 ft/sec^2 which is half a g. That level of braking is not possible until speed is low enough to remove most of the lift and thus have most of the weight on the wheels.