tdracer,
No need for you now to resort to personal attacks, just stick with the facts.
Wait a minute swh, I went back and re-read your first post, did you really just use the SLS 30% fn number to determine "cruise" SFC? REALLY?
No, I did not say that, I said I presented the 30% rated thrust numbers. I further said I expect the cruise TSFC to be around 0.2 higher than the numbers presented, i.e. around 0.5.
While I fully acknowledge and agree that the test cell numbers are not the same as what will be seen installed on the airframe in cruise, the relative differences should not see any massive change.That is the point of having the tests and compiling the database. The tests are a standardized method of measuring engines against Annex 16, the actual installed thrust rating and limits are another matter.
One cannot make a statement saying the tests pose no relevance, why do the tests at all if that were the case.
Jet engines have what is referred to as an SFC "Bucket".
I did "plot" the 100%, 85%, 30%, and 7% numbers to get the polars, I had calculated the TSFC for every condition in the respective reports. I am aware of off-design conditions/considerations, hence why I have not try to deal with the installed conditions. Many factors outside of the engine manufacturers control start coming into play, for example the 747-8 has a lower initial cruise capability compared to the 788. A relatively easy way I use to get a better idea of cruise level data is by using tools like GasTurb, it does enable one to look at off-design conditions as well. I know it is not perfect as the maps are out of date compared to the latest R&D, however is it better than a wet finger into the wind.
Now, try to imagine this for a minute, even though an engine at 39k cruise is producing ~10%-20% of what the engine can produce SLS (since air density is so low), it's operating at 80 or 90% of it's rated thrust - in the sweet spot of the bucket.
This is the Mach/Altitude of relationship I would expect for any modern turbofan, taking M0.8/11km back to sea level, what percentage of max takeoff thrust do you come up with ?
aside from ratings plugs on the FADEC, they are identical engines
That is not true, the CF6-80C2 started off with mechanical control, FADEC was only introduced last 1980s/1990 (all 400 engines were FADEC). Over the years all the manufacturers make improvements. Some of the relevant GE press releases from 2002 and 2010.
GE Engine Services Launches CF6-80C2 Engine Upgrades; Upgrade Enhances Engine Performance And Time On Wing | Press Release
GE's CF6-80C2 Engines Celebrate 25 Years of Flight and Counting | Press Release
This article deals with a lot of the issues with the engine, and what was changed.
http://www.iasg.co.uk/pdfs/articles/...ne_history.pdf
It also explains your garbage for the RB211
The tests are performed to Annex 16 requirements by the manufacturers, they are what they are. They are not independently tested in a common test facility.