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757 Captain III >> 757 Captain III - General >> Derate temperatures and Topcat https://www.captainsim.org/forum/csf.pl?num=1601154206 Message started by spence on Sep 26^th, 2020 at 9:03pm

Title: Derate temperatures and Topcat
Post by spence on Sep 26^th, 2020 at 9:03pm

Hello,

I am running into a bit of an issue with Topcat's performance data and the CS 757. On a relatively lightly loaded aircraft, Topcat is calling for a derated temp of 68c, but the fmc won't accept a larger value than 52c. Now sometimes the EPR doesn't match up with Topcat, but this seems like quite a big difference.

Screenshot_1_004.jpg ( 148 KB | 47 Downloads )

Title: Re: Derate temperatures and Topcat
Post by Angel of Attack on Sep 27^th, 2020 at 1:12am

As pre reglation, you shouldn't have more than 25% of thrust reduce. also there would be envelope for max temperature at different altitude.
As my exprecnce, EPR is quite close at most of the time, but it could be different for many reason.