For the original question, then, what is the practical application of this? Do light-aircraft pilot's handbooks have any guidance/charts (ala Figure 7.20 of Wizo's link), or is this all just theory? You'd be a brave pilot to reduce the Vx from say 60 to 50 thinking you were going to outclimb a hill because you had a bit of headwind. For example, John Lowry (in Wizo's link) is suggesting that, in a 30kt headwind, the Vx reduces from 64 to 48. Surely he can't be serious? I don't know a lot about flying light aircraft, but I would have thought that if you reduced Vx by that much you'd be dead in a flash if on one engine.
Certainly, I wouldn't have a clue in my Boeing whether my takeoff performance data reduces the V2 slightly in a headwind. I just fly at the speeds the FMS determines.
PS: John has "Bootstrap" on the brain!
