Hi enicalyth
All received, thanks. Useful insight into the A400M. I took a long look at the C-17A after your post and found a little trap which I hadn't known existed (due to my limited and doubtless ignorant horizons).
Its flexible ACN does drop quite a bit using the 2007 alpha factors, which is to be expected with 6 wheels per main gear. The trap is in the rigid pavement ACN. The 'rigid cutoff' is limited in software to 3.00 times rrs to comply with ICAO's ACN calculation. This gives odd ACNs for rigid pavements, which only become sensible with the Rigid cutoff set to say 5.
FAA says "the standard ACN cutoff for rigid pavement stress computation is 3 times the radius of relative stiffness (rrs). This gives inconsistent results with large complex gear configurations such as the C-17 (high-strength ACN higher than low-strength ACN)."
Ok - now I know. I think this might be quite humorous to let loose on my students and see who picks it up
