EPR (FS vs. Yours)

[jotel]

Hi there,

as you may know or not, I'm working on my own DC-8 Panel and I stumbeled across a problem there regarding the EPR Values. I made a simple EPR gauge, reading the values from FS (using: A:ENGx PRESSURE RATIO,ratio) and I took yours to compare and I found a significant difference... using your gauge, I can fly the DC-8-50 by the table and it checks with the table (also N1 vs. EPR) but using the standart FS values, no way...
see for your self



Could you HJG guys give me some tips how to get build a correct EPR gauge for the JT3D Engines used on the -50's? Why is FS giving such strange values?

Regards

Johann

[George Carty - HJG]

FS EPR is useless. I calculate EPR from Corrected N1 using polynomials (cubic below 60% CN1, quintic above that), and then apply corrections for airspeed, Mach and (for the 707 panels) turbocompressor status.

I wouldn't know how to write those complicated formulae in XML though - I'm a C man through and through ;D