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757 Captain III >> 757 Captain III - General >> EPR value PW2037 vs 2040 RB211-535E4 vs E4B
https://www.captainsim.org/forum/csf.pl?num=1640889041

Message started by Alex T on Dec 30th, 2021 at 6:30pm

Title: EPR value PW2037 vs 2040 RB211-535E4 vs E4B
Post by Alex T on Dec 30th, 2021 at 6:30pm
I just noticed the EPR values for PW are all based on 2040s and RR are all 535-E4Bs.

I have plenty of charts for real EPR values for all engines, is this something that can be added to the list? The max EPR for the PW2037 ISA conditions at sea-level is 1.41EPR, not 1.47 like its 2040 counterpart.

I can also provide plenty of charts for N1 takeoff values too and assumed temperature estimates. 

Title: Re: EPR value PW2037 vs 2040 RB211-535E4 vs E4B
Post by Alex T on Dec 31st, 2021 at 3:29am
Not sure why I just spent hours making this spreadsheet.. but it shows the expected values for every DA combination with assumed temperature. Hoping CS will consider changing some values around to reflect each engine? if not I will gladly do it myself with the dll source code  ;D

https://docs.google.com/spreadsheets/d/1EJGI_3zcvbxoZrqXM3xJJemff-ce6ciWsSVVC8Ia7To

Title: Re: EPR value PW2037 vs 2040 RB211-535E4 vs E4B
Post by Alex T on Dec 31st, 2021 at 3:30am
Long links don't work here.. this is the spreadsheet

https://bit.ly/3eB8quz

Title: Re: EPR value PW2037 vs 2040 RB211-535E4 vs E4B
Post by Angel of Attack on Jan 1st, 2022 at 12:54am
Thanks for share the data!
Just make a correction, N1 doesn't goes up and down with ATM as actual temperature. Once you use ATM over refTemp, N1 always lower than what current temp's N1 would be.
For EPR controlled Engine like PW and RR, you only need to get EPR, and let EEC to tell what N1 should be, but for N1 controlled engine like GE/CFM, there is a more complex 3 tables (on 737 at least as I know) to look for correct N1 (I guess that's why it doesn't work well on the 767GE expansion, though I didn't bought it so can't tell)

Title: Re: EPR value PW2037 vs 2040 RB211-535E4 vs E4B
Post by Alex T on Jan 1st, 2022 at 6:35pm

Angel of Attack wrote on Jan 1st, 2022 at 12:54am:
Thanks for share the data!
Just make a correction, N1 doesn't goes up and down with ATM as actual temperature. Once you use ATM over refTemp, N1 always lower than what current temp's N1 would be.
For EPR controlled Engine like PW and RR, you only need to get EPR, and let EEC to tell what N1 should be, but for N1 controlled engine like GE/CFM, there is a more complex 3 tables (on 737 at least as I know) to look for correct N1 (I guess that's why it doesn't work well on the 767GE expansion, though I didn't bought it so can't tell)


Thank you!

That N1 box is more as a reference to what expected MAX N1 should be for a given reference temperature and pressure altitude, as of course EPR is the main thing we're aiming for. It's just there as a reference! Maybe I should take it out completely as it's a little irrelevant. But since I'd love for CS to change the N1 values to reflect 2037 vs 2040, maybe I should keep it? Currently not only EPR but their N1 values for the 2037 and -535E4 are wrong.

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