High Transonic Mach Number cruise

[WeekendFlyer]

Some of the modern business jets seem to manage very high cruise mach numbers, M0.9 or even slightly above. Does this mean they are cruising at speeds faster then their drag divergence Mach Number (Mdd), or has a very careful combination of wing sweep, supercritical aerofoil and low thickness/chord ratio been used to make Mdd higher than Mach 0.9? From my understanding of transonic flight I thought designing a wing with a Mdd much above M0.86 or so was a really tricky challenge, both aerodynamically and structurally.

I also note that most civil airliners cruise somewhere in the range M0.8 to M0.85, or thereabouts, so I am surprised that business jets cruise faster. Perhaps business jet operators are just happy to burn more fuel in order to get somewhere faster?

Any thoughts on this would be welcome!

WF

[WeekendFlyer]

Igh, thanks, interesting! I'd forgotten about the sonic cruiser but found this:

Analysis of the Sonic Cruiser Concept (http://www.mh-aerotools.de/company/paper_7/astec_2002.htm)

Seems they managed to move Mcrit above M0.8 and Mdd to somewhere in the region of 0.95, but required very low thickness/chord ratio and a long chord to achieve it.