“Engine performance comes from a blend of propulsive efficiency (generated by the fan) and thermal efficiency generated by the core. Roughly 50% of a modern engine performance is dictated by each element. The GTF, with a larger, slower turning fan, has an advantage in propulsive efficiency, and the LEAP, to provide equivalent fuel burn improvement, would need higher thermal efficiency. That would require a hotter burning engine.”
“Airinsight estimates that the PW1000G will have between 1,500-3,000 fewer airfoils, six fewer stages, and about the same number of life limited parts in its configuration when compared to the latest information we’ve obtained on the LEAP.”
“We would expect the GTF to have an advantage in maintenance costs over the LEAP based on two factors – fewer parts and slightly lower (turbine) temperatures.”
We now need Lightsaber to add his expert analysis to this article.
MarkC From United States of America, joined Apr 2006, 259 posts, RR: 0 Reply 2, posted (2 years 3 weeks 5 days 1 hour ago) and read 5710 times:
I will preface this by saying that I do not work on the GTF (given my employer), and will defer to Lightsaber in all areas except my personal areas of expertise (overhaul).
I did not know that CFM was going for a 2 stage HPT. This was one of their maintenance advantages on the CFM over the V was to have a 1 stage HPT vs. 2 for the V. Lower maintenance costs, but, I guess they needed the fuel burn numbers and had to go 2 stage. And, I had no idea they had a 7 stage LPT. This is incredible. Is that true? CFM LPTs are exceptionally robust, but if there ever is an issue with an upstream component, and it creates a cascade effect failure, its going to be an expensive bill for a repair. Hell, a 112 inch PW 4000 has a 7 stage LPT. Incredible for such a small engine. You should see a bill for a 112 inch HPT blade failure that takes out the LPT. A 7 stage LPT has an incredible blade count.
However, the CFM has a great advantage with the composite blades in the fan. They can build the containment case so much lighter with those blades.
Who knows. If GE can deliver on their promise on the temp increase for the core, that is scary news, because they have always been behind PW in metallurgy and coatings. I personally hope/believe that PW can increase the temp later to keep ahead.