xp-0001r -> After some "bug" - fix you need to push "FL_CH" button instead of the "V_NAV" button to get a "climbing angle for constant speed" and set the speed directly on autopilot (Default set is 200 Mph).
When reach 10 000 feet, the optimal speed is 290, and on ca 24- 25 000 feet you go over to MACH 0.8.
The point to set 0.8 Mac is that on FL 310 and over the sound speed is getting lower, so the plane automatically lowering the speed to constant MACH0-8 instead. The maximum speed for B 744 is about 0.9 MACH. and this is 270 knots on FL410.
If you instead Fly on V_Nav the plane follow the setting in FMS as I mentioned above!
However, I have not find any way to fly on vector and reach ILS. It seams to be a bug-fix waiting to be able to fly on STAR-approach with Vectors at the finish.
THE FMS - STAR vectors is not possible "to follow" there is occoring "impossible" turns, and no glide-slope at the finsih... end....