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teropa
25th Mar 2004, 07:01
Hello,

I'm writing to help out a team, who are in the process of simulating a 757 engine into a simulator (PW2040 stands as a good example).

The 757 engines are all EPR-based. The problem with the simulator is that it can only accept N1-values as the basis of the flight model.

Question: Who / what could provide me with tables that have EPR vs. N1 values in them ?

I have checked the AOMs, and they indeed have a few alternate thrust tables, but they aren't enough by a long shot.

If anyone could help me with this, I would appreciate it a lot!!!!

kind regards,
Tero
CR2
25th Mar 2004, 10:30
Have you tried writing to Pratt & Whitney? You never know...
teropa
25th Mar 2004, 14:58
Hi !

Yes, in fact I have :). I just received a reply from them, that "they will not entertain requests for academic research assistance".

So much for them I guess. I wonder how big of a deal would it have really been for them to provide that info. And before anyone starts telling me that I'm on the last priority when it comes to their wheeling & deeling: I know it.

Tero
lomapaseo
25th Mar 2004, 15:52
Yes, in fact I have . I just received a reply from them, that "they will not entertain requests for academic research assistance".

So much for them I guess. I wonder how big of a deal would it have really been for them to provide that info. And before anyone starts telling me that I'm on the last priority when it comes to their wheeling & deeling: I know it.

Tero

Customer service starts with a customer:}
teropa
25th Mar 2004, 18:35
:p It sure does!
mono
26th Mar 2004, 08:13
That will be a fairly complicated algorithm!!

There is no direct N1/EPR relationship. There are too many external factors. Pressure, temperature and even humidity will change the EPR for a given N1 speed. The lower the temperature or greater the pressure density, the less N1 will be required to achieve the required EPR.

The MM has reams of correction tables which will give temperature/pressure corrected N1 values but for the N1 to EPR relationship there is still a range of values which are acceptable for maintenance purposes.