Does everyone realize how *expensive* it is to flight test an aircraft at hot and cold conditions? The A380 had to chase cold temperatures and *repeat* cold weather certification to reduce its minimum cold temperature.
The same is true of hot or cold temperatures. Planes must proves sans passengers the extremes. The *only* exception I'm aware of are antarctic flights with the BT
-67 (turboprop conversion of the DC-3) and that is because lives can be on the line if its too cold to fly and the only way to find out if the plane can take it is to continue with the flight. (But that is all researchers and thus subject to signing the waiver.)
And also true of cross wind certification... No extrapolation outside of the tested box allowed. It must be proven.
Also, does anyone have a link to CRJ performance with temperature? I didn't find them quickly Googling... (Thanks in advance.)
|Quoting nutsaboutplanes (Thread starter):|
US Airways has stopped RJ flying in PHX as of 1500 due to high temperatures as CRJ performance charts stop at 117.7 degrees. It is currently 118 at PHX.
Oops! Sort of amusing.
|Quoting Viscount724 (Reply 3):|
I think -40 is the CRJ's lowest certified operating temperature.
Now that is ironic...
|Quoting cornutt (Reply 4):|
Is it a function of engine power or lift that makes them not able to fly at these temperatures?
I'm curious to that too... the CRJ, IIRC, has a higher wing loading, so it could be that the takeoff performance deteriorated too much to make it worth certifying... But I speculate.
|Quoting ely747 (Reply 14):|
Why is this the case? One would assume performance charts of all plane makers are standardized by the ICAO.
You are required to certify to > 7,000ft (I forget what is the exact altitude) and to 86F. Everything above 86F (30C) is gravy... Now, few if any airlines will buy a plane not certified to 114F (45.5C), but few will have the need.
Pratt typically designs engines to 125F, but that is their 'standard work.' No ICAO requirement. Why 125F? Its simply too rare to see above that. (Something like 99.99% day in the hottest place on Earth, Death Valley. Yes, I'm aware of the debate of invalidated data from Libya... )
|Quoting rampart (Reply 19):|
I would have thought that airlines and manufacturers would have figured out how to certify for those times when temperatures exceed 50C.
Why for all airliners? Oh, they engineers aim for 125F (51.67C) or 50C, but that is a goal. Temperatures above 114F are very rare in aviation and to certify that temperature one must fly in that temperature! Apparently Bombardier tested 117.7F and said 'good enough.' Judging by their sales, so did their customers...
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