Re: EPR v. N1 for turbofan power setting

From:         nordstrom@esa.lanl.gov (Carl Nordstrom)
Date:         03 Mar 95 02:27:48 
References:   1 2
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> The problem with N1 is that it does not take into account wear an tear on the
> fan blades.  As they get worn they may not produced the thrust they did when
> they were new.  On the newer high bypass engines they are the best choice
> because EPR is not accurate on high bypass engines.

It seems that you could use *corrected* N1 and always get a proper
indication of thrust in high bypass engines.  High bypass engine fan
blades do not suffer the wear and tear of smaller engine fan blades as a
percentage of core flow, so I would wager that this would be a good
indicator.  Of course, I don't know if pilots would feel comfortable with
a mathematical approach to thrust, as opposed to a direct reading of N1
(and the subsequent table lookup to arrive at thrust).

Carl Nordstrom
nordstrom@esa.lanl.gov