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Boeing 777 With PW4090s  
User currently offlineAirxLiban From Lebanon, joined Oct 2003, 4506 posts, RR: 54
Posted (8 years 1 month 7 hours ago) and read 4347 times:

I thought I knew the answer to the question of why the PW4090 powered 777-200ERs have a lower MTOW than their Trent and GE90 siblings but after reading through some material here I'm not so sure anymore.

Past topics include this one:

http://www.airliners.net/discussions...h_ops/read.main/119950/6/#ID119950

Which says that it was something to do with emissions.

Is the PW4090 certified in all categories (including emissions) to beyond 90,000 lbs of thrust?

What is the maximum range of the 777-200ER with the PW4090?


PARIS, FRANCE...THE BEIRUT OF EUROPE.
6 replies: All unread, jump to last
 
User currently offline777WT From United States of America, joined Jan 2005, 875 posts, RR: 1
Reply 1, posted (8 years 1 month 5 hours ago) and read 4323 times:

Not only that, but it had the worst fuel burn than the GE90 and Trent.

User currently offlineAirxLiban From Lebanon, joined Oct 2003, 4506 posts, RR: 54
Reply 2, posted (8 years 4 weeks 1 day 7 hours ago) and read 4178 times:

So what is the range of the 777-200ER when equipped with the PW4090?


PARIS, FRANCE...THE BEIRUT OF EUROPE.
User currently offlinePhollingsworth From United Kingdom, joined Mar 2004, 825 posts, RR: 5
Reply 3, posted (8 years 4 weeks 15 hours ago) and read 4081 times:

Quoting AirxLiban (Thread starter):
Past topics include this one:

http://www.airliners.net/discussions...h_ops/read.main/119950/6/#ID119950

Which says that it was something to do with emissions.

Is the PW4090 certified in all categories (including emissions) to beyond 90,000 lbs of thrust?

What is the maximum range of the 777-200ER with the PW4090?

The emissions statement doesn't make much sense. The following is what was quoted

Quoting Lightsaber:

The reason for the pw4090 thrust limit is simple: Emissions. The pw4090 at 90,000lbf of thrust puts out 99.2% of the allowed ICAO NOx emissions. This is the highest certified thrust that Pratt is allowed to sell on the market. You are not allowed to fly into/out of a FAA or JAA airport without meeting ICAO emissions. In other words, the pw4090 is certified for 91,700lbf of thrust in every criteria *except* emissions. But you're not allowed to miss even one certification criteria... Note that the pw4090 has no trouble with the smoke or Carbon monoxide portions of the emissions certification.

The reason it does not make sense is that the ICAO emissions stringencies were adopted by the FAA and JAA/EASA as certifiction requirements. This means that you cannot certify an engine period unless it meets these limits. The PW4090 is certified for 91,790 lbs of take-off thrust. This means that at the level it was certified it met the emissions requirements.

http://www.airweb.faa.gov/Regulatory...5786256a080048f7ea/$FILE/e46ne.pdf

The main issue is that the 91,790 is an uninstalled thrust number. It will produce less when installed. Hence the 90,000 lb number. As for comparing it to the GE90-92B, legally in the US the -92B no longer exists. The engine is now type certificated as a -94B or was down rated to a -90B, GE withdrew the type certification for the -92B when the -94B was certified and all -92Bs were upgraded to -94B bill of materials or downgraded to -90Bs. Incidentally the -90B is rated for 94,000 lb (97,300 for the -94B) max-takeoff thrust and 90,580 lb max continuous, same for the -94B. The Pratt is only rated for 74,950 at max continuous. This hurts overall performance.

http://www.airweb.faa.gov/Regulatory...62570fc005486d6/$FILE/E00049EN.pdf

As for emissions the ICAO emissions databank lists the PW4090
http://www.caa.co.uk/docs/702/3PW066_01102004.pdf
as producing 98% of CAEP/2 NOx and 108.8% of CAEP/4 NOx at a rated output of 395kN (~82 klb).

The GE90-92B (it still exists in ICAO) with a DACI (similar generation)
http://www.caa.co.uk/docs/702/3GE061_01102004.pdf
is given at 80.1% of CAEP/2 and 88.2% of CAEP/4 NOx at a rated output of 426.72 kN (~96 klb).

The newest -90B (-94B bill of materials with DACII)
http://www.caa.co.uk/docs/702/6GE090_01102004.pdf
is at 81.5% CAEP/2 and 90.3% CAEP/4 in NOx, rated output is 418.1 kN (~94 klb). None of the engines has issues with CO or HC

The LTO NOx for the GE90-92B(DACI) is ~31kg ,GE90-90B(DACII) is ~28kg, for the PW4090 it is about 32kg. Incidentally the GE90-115B has an LTO NOx emissions of ~35kg.


User currently offlineLightsaber From United States of America, joined Jan 2005, 12779 posts, RR: 100
Reply 4, posted (8 years 4 weeks 4 hours ago) and read 4019 times:
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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.  Wink If one can get one thermocouple measurement "adjusted" just a little bit... there is your 1.2% change due to a correction factor.  Smile

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.  Wink

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.  Smile

Oh, on the pdf link for the pw4090, 395kn=88,800 lbf thrust... So something is not adding up...  scratchchin 

I don't have the exact number on the 772's range with the pw4090, so I'll let someone else post that.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlinePhollingsworth From United Kingdom, joined Mar 2004, 825 posts, RR: 5
Reply 5, posted (8 years 3 weeks 6 days 17 hours ago) and read 3978 times:

Quoting Lightsaber (Reply 4):
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.  


I wasn't actually picking on your 99% number  Smile . I was just posting the actual values. My complaint was the impression that the 4090 was certified to 91,790 except for emissions. While the 4090 might be designed to produce more than that it is not certified to do so. I guess I should have been more explicit.

Quoting Lightsaber (Reply 4):
Now as to continuous thrust, that's due to the guide swirlers. But hey, I don't make sense.  

That makes sense, my only statement here was that there was an even greater performance difference than the take-off thrusts would seem to indicate.

Quoting Lightsaber (Reply 4):
Oh, on the pdf link for the pw4090, 395kn=88,800 lbf thrust... So something is not adding up...   

Thanks for catching my typo, it is 88 and not 82 klb. What is interesing about this is that this number maybe what the US regulatory compliance tools, that airports use for Part 150 studies and EISs, will have in there performance databases (though I think that there is only on 777-200 entry in the performance portion).


User currently offline777WT From United States of America, joined Jan 2005, 875 posts, RR: 1
Reply 6, posted (8 years 3 weeks 6 days 8 hours ago) and read 3930 times:

Quoting Lightsaber (Reply 4):
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.

I didn't post any links in this thread.


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