View Full Version : Coffin Corner
Niallo
7th Jun 2009, 19:20
I have read with great interest the posts concerning the diminishing range of allowable speeds for a heavy airliner at higher altitudes, ie between stalling and overspeed. Is there any significant difference between say, the A 330-200 and the B767-300, in their allowable speed range at similar heavy weight and high altitude?
Niallo
9th Jun 2009, 14:56
As of now, 377 viewers of this question but zero replies!
Is this because:
It was a dumb question?
The question was badly written?
To provide an answer would be too time consuming?
There is no clear answer?
Neil
Old Smokey
9th Jun 2009, 15:19
There have been no replies because each aircraft is uniquely different to another. To take the point even further, the same aircraft type at differing weights exhibits entirely different characteristics as the weight varies.
Apples and Pears, Chalk and Cheese...................:confused:
Regards,
Old Smokey
OverRun
10th Jun 2009, 01:38
So this thread is not left hanging, with the scepter of the coffin corner unanswered, ELAC in R&N here (http://www.pprune.org/rumours-news/376433-af447-23.html#post4985564) said the following for the A330-200:
At FL350 and 210 tons my A330-200 (slightly different engines) would have had a barberpole at M.86 of 292 KIAS and a Vls 1.3G of 241 KIAS, a spread of 51 kts. A M.80 cruise would have been at 272 KIAS and the recommended TAPS would have been 260 KIAS. At either speed there would exist an approx. 20 KIAS margin to the nearest limiting speed, let alone the nearest actual buffet speed. That's a pretty wide margin to operate within and hardly anything like a coffin corner.I don't have the same data for the 767-300.
Bullethead
10th Jun 2009, 02:30
Max AUW of a B767-300 is 185 tonnes so there can be no viable comparison with these Airbus figures.
Regards,
BH.
Old Smokey
10th Jun 2009, 04:12
Thank you al446, I stand corrected:ok:
Regards,
Old Smokey
Lightning Mate
10th Jun 2009, 14:12
I have just been looking at Buffet Onset Boundary charts for three different jets and, whilst they all look the same, they are not when you put some examples in.
Things such as wing section, % MAC of C of G, weight etc. all come into play. Thus the range between low and high speed stall will vary from aircraft to aircraft.