EPR AND IEPR
 

CAN SOMEONE EXPLAIN THE DIFFERENCE BETWEEN EPR AND IEPR?
IF EPR IS THE RATIO BETWEEN COMPRESSOR INLET PRESSURE AND NOZZLE PRESSURE WHAT EXACTLY DOES AN EPR OF SAY 1.5 MEAN IN SIMPLE TERMS?

If you do an advanced search, all will be revealed! there are 13 threads that go back to 2001, they should have all the information you are looking for:ok:

EPR : Engine Pressure Ratio

Differs depending where the probes are positioned. P&W use different locations to RR, therefore for the same thrust amount the EPR's will differ significantly.

It's basically the Exhaust (Hot stream) pressure divided by the inlet pressure.

RR use IEPR (I = Integrated) as they use Exhaust (Hot stream) + Fan Exit (Cold Stream) divided by Exhaust pressure.

Also IIRC RR has stopped using IEPR on the Trents the last engine was the RB211-524G/H on the 744/767.

SMOC