I'm not disputing the Convairs were able to cruise faster but my original point stands. The old
obsolete 747 could
fly at Mach 0.99 which was a creditable aerodynamic achievement.
If it was at 10 degrees and say at full power... let's say the engines produce 60% power at cruise altitude. Sine 10 degrees on 300 tonnes gives us 28750 pounds per engine. Factor that by 100/60 and add to the 50000 pound engines it's already got and that means you'd need four 98000 pound engines to turn your 747 into a Mach One Cruiser.
Dear Rolls Royce...