mutt:
Quote:
The assumed temperature must not be lower than the flat rating temperature
Why not?
Quote:
exceed 25 % of the full rated takeoff thrust
Why is this restriction applicable to the full rated takeoff thrust, why not the rating in use?
The first applies to our E-jets. Any Assumed temp below Min Assumed Temp(flat rated temp) will not produce a reduction in thrust. If you look at the figures for an assumed temp below ISA+15 (ISA+20 for your jets I think) the N1 reduced is always the same a s the N1 for To thrust at the ambient temp.
As for the second point I'm with you. the 25% reduction is applicable to the Rated Thrust or De-Rated Thrust.
As for d and x graphs, many moons ago in deapest Africa a Nimrod crew were a bit limited so they pulled out the books the night before and 2 pilots and 2 FEs each did a calculation. In the morning we ehrrr.... they compaired the results and used the most limiting of the 4 different answers they had.
Thank the lord for computer generated runway analysis!!