Originally Posted by
Mk 1
Why the lack of development? More profit in the bigger engines in the 60k+ lb thrust range? More demand? Or the lack of an airframe to match it to?
I think a big part of it is that the engine companies have had their hands full with other stuff. Since 1990, GE's done the GE90-94B, the CFM56-7, GE90-115B, part of the GP7000, GEnx-1B, GEnx-2B, two version of the LEAP, and now the GE9X. All good, successful engines (GE9X still
tbd), but that's a lot of development time and money. Similarly Rolls has been busy with various versions of the Trent and currently has their hands full solving in-service issues with it. Pratt has bet the farm on GTF - the jury is still out on the long term wisdom of that but they have their hands full making that work at the current scale, never mind up-scaling to NMA size.
It becomes a bit of a chicken or the egg problem - you can't design an aircraft without an engine, but the engine company doesn't want to spend money developing an engine without something to put it on.
Unlike some other posters, I don't think Boeing is giving up on the NMA, they are just putting it on hold while they get the rest of the house in order.
I think the first pilotless (or even single pilot) aircraft will be freighters - not passenger aircraft.