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Thread: Why EPR?
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Old 25th Apr 2016, 13:38
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FullWings
 
Join Date: Dec 2003
Location: Tring, UK
Posts: 1,847
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I’ve had a fair amount of experience with EPR and N1 as the primary reference and on the whole, I prefer N1 now.

The older engines seemed to have a “truer” EPR display, i.e. 1.0 was zero net thrust and 1.6 was twice as much as 1.3. The RR Trent is happy pushing 250T of aircraft along at 250kts with an EPR<1. How does that work? Also, due to the huge variation in required TO EPR with altitude and temperature, there are no “ballpark” settings - at least none that I can remember. Doing circuits N1 is a lot better for a initial stab at a power setting.

With thrust synced between engines on EPR, you get that annoying phasing vibration that you don’t get with synced N1s. N1 is also a more robust measurement in that probe icing, etc. doesn’t affect the reading. I hear RR might be going to N1 as primary in the near future, anyway...
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