Does it seem to anyone else that Boeing and the engine OEM's are being more conservative than we might have thought a few years ago? Maybe due to recent problems with new engine platforms?
Yes. As per #66 above, Boeing's CEO is being really conservative by asking for “existing engine technology packaged in a new way”, presumably because of the recent engine problems.
Here's the quote:
Boeing chief executive Dennis Muilenburg said recently that the company is seeking “existing engine technology packaged in a new way” to reduce development risk, upfront investment and increase the likelihood its propulsion suppliers will deliver on time.
Boeing must be considering the challenges with the Trent 1000/7000 and PW GTF. 787s and A320s are grounded around the world due to engine issues. The A330neo is in limbo waiting for engines. It makes me think they will go dual source or very low risk.
Setting the bar at +25% relative to 757 SFC is a low bar, but it'll sound good to the uninformed.
Ha maybe read closer next time, Matt.
Over the past couple years I've gone from being a big booster of this project to being very suspicious when the first "LEAP 1.5" noises started coming from Boeing/GE.
The new article quantifies the more conservative engines at ~25% SFC, which is better than I worried for LEAP 1.5 but not as good as we could have expected a few years ago.
I wish Leeham and/or others would issue a more transparent model wherein we could evaluate the likely performance characteristics based on given SFC's. IMO the NMA is a slam dunk with -30% SFC delta (relative to 757), a likely no-go with ~20% SFC delta (i.e. only a little better than LEAP), and somewhat ambiguous at -25% delta.
I just hope that, if Boeing can see 6-7% better engines (.70 vs. .75 compared to 757) by waiting a few years for Ultrafan-gen engines to mature, that Boeing waits. Otherwise we could see an A330 replacement swamp the NMA a few years after its EIS.
Actually, if we could be guaranteed that outcome (NMA plus much better A330R) I'd be happy as a consumer. Boeing shareholders would be rightly mad.
I know you know far more than I about the difference between engine performance vs total airplane performance, and how weight and aerodynamics also play roles, but it appears youve mixed the two.
No I'm doing estimations in my head of the plane-level characteristics of an NMA with various SFC levels. I've posted approximations of the -30% SFC NMA in several older threads; it's not extremely hard to guesstimate the impact of a ~6% increase in SFC on plane-level performance (more fuel carried, bigger wing/engines/empennage/MLG, then an iterative loop).
I don't recall the exact number or cites, but Boeing has previously projected economic
improvement in excess of 20% versus 757/767, which implies vehicle-level fuel burn improvement on the order of ~40%. That seems about right to me when combining ~25% SFC delta with aero and structural improvements.
40% is a big number but I'm not sure it's quite enough to future-proof this aircraft. Boeing needs a platform that is a hands-down winner on 6-10 hour routes AND better than contemporary NB's on shorthaul. Given NMA's likely higher acquisition cost than NB's, it will need a serious fuel burn edge on shorthaul.