Hi Hessel.
Well spotted on the ATM derate! I deliberately glossed over that as I know it doesn't tie in.
Hardy is aware and we are looking at a possible resolution, ...
Hi Peter,
last time we emailed, -20% from 1.56 doesn't make 1.36 as Hessel suggests, but 1.45 :-)
The results in PSX should be correct now since beta 8.
If Hessel's formula was right, 100% reduced from 1.56 would be 0.56, but that's reverse thrust actually, and not zero thrust. Zero thrust at zero Mach is 1.00 EPR.
I'm sure you agree: When 1.00 EPR produces zero thrust, the value after the decimal ist the actual thrust value. E.g. when we have 1.43, the % factor needs to be applied to the value 43. E.g. 10% of 43 is 4.3. E.g. 1.43 - 10% = 1.43 - 0.043 = 1.387 EPR.
:-) OK, I see you agree:
The percentage reduction is take off the figure after the decimal in this case "70" so 10% would give you 1.63, 20% would give 1.56.
But that's how it works in PSX. Why are you saying it needs to be "resolved"?
The only point left over is the assumed temp in PSX being limited at 63°C (as observed on some real aircraft), while at BA it goes to 70°C.
Regards,
|-|ardy
P.S.: A tip on the takeoff CG entry in the FMC: If a weight & balance computer is not installed, you can look up the true CG on Instructor > Situation > Aerodynamics.