The quoted Mdf of 0.998 for the 747 makes me smile.
First because it's only about 1 kt below Mach 1, secondly because an accuracy of 0.2% so close to Mach 1 is unlikely (think Machmeter and VSI "jump").
I would think they probably "hit" Mach 1 and a bit, but didn't want to write that in the final report
Oh, and to add another "airliner" to the Mach 1 club:
The RAF VC10s have the shorter fuselage of the early model VC10, but the more powerful engines of the later models.
It is told (but never confirmed officially
AFAIK) that when empty and with most of the fuel burned off, they actually could reach and exceed Mach 1 in level flight at altitude......
Condor66,
I'm afraid you're barking up all the wrong trees.
- Jetliners are designed to
withstand that sort of speed. The DC-8 supersonic dive was part of the flight test programme.
They are not designed to
operate at that speed, because of the drag rise.
- There is no "tremendous buffet". We left that behind in the '50s.
- You don't need a Concorde-like sweep to reach and exceed Mach 1. The Sabre, the Hunter, the Mig-15 all had 30° to 35° sweep, and all were supersonic in a dive.
- You don't need a "supersonic" airfoil either to go supersonic. The aircraft cited above do not have "supersonic" airfoils, and neither does the DC-8.