Viable SST...

[elmayerle]

Hi Evan,
an old one of course, preferably a 195 or the 1949 170A I jumped out of a few times.

Actually, I prefer the modified 170A a former co-worker was involved with.  Without modifying the cowl, a Continental IO360 was installed in place of the O200.  I gather this made for rather spritely performance.  My choice would likely be a 185 with the floatplane kit installed.  

[elmayerle]

Well the GE.4 worked, possibly the ONLY bit that did of the US SST effort, and ironicaly Concord would have benefited from that engine, I suspect you could power Concord with just two GE.4s, certainly three.

Actually, P&W's entry worked well, too.  Imagine a Concorde powered by those with better subsonic fuel consumption, it would definitely have improved the economics of the aircraft, though I've no idea if that by itself would've been enough.

[elmayerle]

I'll second what Jon said about the major re-design of the 747 in the 1990s.  My employer at the start of that decade, Northrop, was heavily involved in the 747 from the get-go as a risk-sharing sub-contractor/partner and they were deeply involved in this effort (I know, I had several friends up there on it).

With the advent and adoption of HSM (High-Speed Machining), it's now possible to do large complex single pieces equivalent to what used to require lots of piece parts and fasteners to do.  This improves both the strength & quality of the aircraft and reduces overall costs.