From: K.G.A.Lewis@sussex.ac.uk (Ken Lewis) Organization: University of Sussex Date: 08 Mar 95 02:59:51 References: 1 2 3 Followups: 1
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dzul (email@example.com) wrote: : Lakshmi N. Chilukuri (firstname.lastname@example.org) wrote: : : EPR is the ratio of the primary (hot) stream total pressure to the : : total pressure of the freestream. EPR should be greater than 1.0 if : : the engine is running. So it is tough to accept your estimate of EPR=0.3 : : for flight idle power! : Maybe an EPR of 0.3 for flight idle is a bit on the low side but the EPR : reading can be less than 1. For the PW4056 (I only know about this : particular engine from experience) the flight idle is around 0.7 . : When the B744 is fully configured for landing ie with full flaps : and gears down, the EPR setting is only around 1.07 . The textbook I was reading last night defines Engine Pressure Ratio as the the ratio of the pressures recorded at the inlet and in the hot exhaust. I dont see how this can be less than one. There must be a jet pilot out there who can say definitively if the EPR dial starts at 1.0 or 0.0! EPR is a good indicator for non-high-bypass engines. N1 may not be a good indication if the engine is worn or has internal damage but still runs OK(ish).