|Quoting Phollingsworth (Reply 3):|
as producing 98% of CAEP/2 NOx and 108.8% of CAEP/4 NOx at a rated output of 395kN (~82 klb).
Ok, 98%. 99.2% was what the engineer working on the project measured. One has to love those correction factors.
If one can get one thermocouple measurement "adjusted" just a little bit... there is your 1.2% change due to a correction factor.
The pw4090 can develop more thrust at takeoff... but it is emissions limited.
Now as to continuous thrust, that's due to the guide swirlers. But hey, I don't make sense.
|Quoting 777WT (Reply 1):|
Not only that, but it had the worst fuel burn than the GE90 and Trent.
?!? The p4098
has the worst due to its fuel burn being botched. The pw4090 has better fuel burn than the trent on long missions (but worse than the GE
-90). On short missions, the ~7,500lbm of weight of the Trents matters more than the small difference in TSFC and thus your statement would be correct. IIRC at about 4,000nm is when the two engines have about the same costs.
Also notice that the GE
-90 used 3 engines for emissions testing (From 777WT's links). Why? If three engines have the *same* emissions (or a low variation) than the correction factor allows GE
to report much lower emissions even if their engines produce ~same emissions as the Pratt. Pratt's cheap. Test the 1st engine and if it passes, no matter how small the margin, clean up the test stand and go home.
Oh, on the pdf link for the pw4090, 395kn=88,800 lbf thrust... So something is not adding up...
I don't have the exact number on the 772's range with the pw4090, so I'll let someone else post that.