-900 V speeds greater than -800 speeds which in turn are greater than -700 speeds (all at the same TO mass) ?
Is it possible that with the additional length of the 800 and 900 they are 'geometry limited' like the MD80/MD90 ie the length of the fuselage behind the Main UC prevents the AC being rotated to the optimum aerodynamic pitch angle at take off, thus increasing the TODR and in turn affecting the V speeds.
Are the different models (700/80/900) rotated to different pitch attitudes at take off ?