What is the N1% with full throttle on a real 757, 747, etc?

From FlightSim

Q:

IF ONE WERE TO PUSH THE THROTTLES ALL THE WAY OPEN ON A REAL 757, 747, ETC, WHAT N1% DO YOU GET?

A:

In simpler terms, depending on the design features/material strength/the exhaust temp etc you will have a max limiting RPM of the engine in figures say 34500RPM. But,an RPM is decided upon as the regular test bed RPM under ideal conditions say 30000RPM. This 30000RPM is termed as 100%N1.So, if any N1 above will be 105% N1 etc.

Now, for every day use we look in the manufacturer's book, which will tell us how much RPM can be used for that day's ambient conditions of temperature, density( Apt elevation),for takeoff purposes for standard operation. From this limit, further limits of overspeed as to how much N1 for how many seconds etc are also specified. Knowing what the normal max power is available, another table will tell us as to how much is the max TakeoffWeight that can be accepted on that day. Other factors that decide these are available rw length,available brake energy,rw slope,obstacles in t/o path,tire speed limits etc. So,if necessary you reduce the payload to get this regulated TOW and take off at that N1-which may be say 110% n1.But suppose, the actual payload is much less, to save on the engine life, you may takeoff at a reduced N1 of let us say 102 % N1 (Airbus calls it Flex N1)once again calculated from a reduced N1 Table, since you dont need that much power for that takeoff.

If these limits are exceeded inflight accidentally, depending on the amount of excedence the engines will be inspected/worked upon/rejected. But,during flight if any dire emergency demands the engine can be firewalled. Repair work on ground comes later.

In fighters since the takeoff weight variation to the basic weight of the a/c is quite small, full throttle is normally used but observing the max EGT limit for the engine. In formation takeoffs you are actually constantly manipulating the throttles to keep in position. In after burner a/c, once again takeoffs can be performed with no burners/min burn/mid burn/max burn etc but all the time keeping within the corresponding EGT Limits.

Bala