Hi,
The discussion on the topic has been interesting - I caught the
Australian article some time ago - and it brings up another facet.
It is possible for an aircraft to climb to its Coffin Corner. I
know. I did. Coffin Corner is described as that density altitude at which
the Critical Mach No. and the stall come together as one. A knot faster and
the aircraft becomes uncontrollable, a knot slower and you stall.
What do you do? Drop the flaps? - and they tear off? No they don't.
Open the Dive Brakes? - at altitude they are ineffective (In the Vampire,
doubling the drag with them took up to 5 minutes to slow effectively). Also
the engine runs at a minimum of 80%RPM just to stay lit at great height. The
real threat is that in entering Critical mach you lose control of the
machine. You won't regain mastery until the control surfaces achieve a
'grip', lower down in thicker air. During this interval, the heart hopes the
device stays together - and it usually does.
I understand the successor to the Vampire, the Venom, carried a much
more powerful engine (which allowed it to climb even higher). This permitted
a delayed Coffin Corner but made descent even more hazardous. I was told
those so trapped actually chose to spin down rather than to run out of
oxygen waiting to increase drag.
That led on occasion to loss of a wing when the spin extended suddenly
through the tropopause and into much thicker air. I don't remember flutter
ever being mentioned.
Cheers, ferg
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