Mutt,
In regards to the Vmcg thread in the pprune flight test forum, I thought I would mention a couple of additional conservative considerations that are included in the determination of Vmcg:
1. Vmcg testing is conducted at aft cg, and with nosewheel either free to castor or lifted off the runway to minimize the stabilizing effect of the nose gear. This has been shown to have a greater effect on Vmcg than a wet runway.
2. Vmcg is determined with sudden failure of the critical engine.
3. The thrust level on the operative engine(s) is the maximum net thrust expected for a production engine (in contrast to the use of minimum thrust for the AFM performance data).
4. Only rudder can be used for control of the airplane (the use of other controls is limited to maintaining a wings level attitude), and the maximum force that can be applied to the rudder pedals is 150 lb.
Mearse.