- #36
etudiant
Gold Member
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boneh3ad said:What do you mean by "Mach effects?" That's not a technical term. If you intend that to mean "compressibility effects," then we've long since passed that threshold. That's roughly Mach 0.7 at cruise. Be that as it may, that doesn't necessarily introduce any control issues. Long gone are the days of believing there is a sound barrier.
Long straight wings at altitude with speeds in the Mach 0.8 class can be nasty, so it does not take a big excursion from cruise to bite.
Afaik, the U-2 at cruise has only about 5 knots of margin between buffet and stall. Admittedly, that is at 70,000 feet, rather higher, but the same caution applies here imho.