Bertie the Bunyip wrote:
Well, the bit of the envelope you're talking about is the low end of the
speed envelope fro every airplane. The coffin corner really only applies to
high alt/high speed transonic airplanes. When you climb up above transition
and reach th ealtitude where the airplane is mach limited the rules
changed.
I've attached a diagram of a typical flight envelope showing the constant
indicated max/min speeds up to transition where they taper in. The point in
dashded lines at the top is the point Bob was talking about where both
happen at the same time. To maintain a margin a max altitude dictated by a
G is determined. Going to fast or sow or pulling too much G at or near max
will result in a buffet and loss of lift, just for starters.





I've just reposted this because I've gotten some e-mail complaining that
the attachment didn't come through. I'll repost that in
alt.binaries.pictures.aviation


Bertie
If you read my post first mentioning "coffin corner", you will notice I
used it as an adjective to describe a "condition" found t the extreme
end of the back side of the power curve; this being the "condition"
where low altitude and no more power available necessitate a reduction
in angle of attack to stop a developing sink rate; a very dangerous
situation on any approach.
It should be obvious that I never meant to convey that the term "coffin
corner" didn't refer to it's classic definition for high altitude
critical mach vs stall condition.
I will not get into a shouting match with Usenet advasiaries who wish to
convey I have no idea what coffin corner is as defined in the
aeronautical engineering sense.
Good God, I've even heard coffin corner used to define
the warnings block on an approach plate!

--
Dudley Henriques