Cold Air

david0tey

david0tey

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Virginia
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Fox-Three
The sub-freezing temperatures this past week in VA have gotten me thinking. I obviously know the effect that cold air has on engine and aircraft performance, and also any problems you would encounter with icing. However, I have always wondered how the cold air affects the structural strength of the airplane. It seems to me that cold air would make certain structural aspects of an aircraft more brittle and easier to break, particularly high stress areas such as the landing gear. I have never understood how airliners fly at 35,000 feet where the air temperature can be -90F and it have no effect on the aircraft. This may be a dumb observation and I apologize if I am wasting your time. But, does the cold air affect the structural strength of the aircraft?
 
david0tey said:
The sub-freezing temperatures this past week in VA have gotten me thinking. I obviously know the effect that cold air has on engine and aircraft performance, and also any problems you would encounter with icing. However, I have always wondered how the cold air affects the structural strength of the airplane. It seems to me that cold air would make certain structural aspects of an aircraft more brittle and easier to break, particularly high stress areas such as the landing gear. I have never understood how airliners fly at 35,000 feet where the air temperature can be -90F and it have no effect on the aircraft. This may be a dumb observation and I apologize if I am wasting your time. But, does the cold air affect the structural strength of the aircraft?
Click to expand...

Do bridges fall down when it gets cold?
 
Dave, your question is a valid one. Cold and heat does affect metal "strength", but obviously we don't add enough force to bring the metal to the point of yielding or failure. At least that is the hope. :lol:

In airliners consideration for the effects of cold are engineered into the system, meaning forces are disbursed to avoid meeting the point at which damage is done landing. There are cycle limits I suppose ( number of landings) before minor or major overhauls though, replacing parts with new after so many landings.

Even small planes are engineered to with stand many times more that the published limits. If I remember right testing required to set load limits is double. If the published limit is +6 G that means the plane must handle 12 G's before yielding (bending) or failure ( I forget which :redface:)

Hopefully, someone current on testing criteria will be along shortly to correct me. :lol:
 
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Geico266 said:
Dave, your question is a valid one. Cold and heat does affect metal "strength", but obviously we don't add enough force to bring the metal to the point of yielding or failure. At least that is the hope. :lol:

In airliners consideration for the effects of cold are engineered into the system, meaning forces are disbursed to avoid meeting the point at which damage is done landing. There are cycle limits I suppose ( number of landings) before minor or major overhauls though, replacing parts with new after so many landings.

Even small planes are engineered to with stand many times more that the published limits. If I remember right testing required to set load limits is double. If the published limit is +6 G that means the plane must handle 12 G's before yielding (bending) or failure ( I forget which :redface:)

Hopefully, someone current on testing criteria will be along shortly to correct me. :lol:
Click to expand...

Certified at 6 means it can go 6*1.5=9 before it will explode and create a black hole and all kinds of other neat things.
 
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Thanks for all the input...except for you "i":wink2:
 
There is, however, a negative to operating in very hot climates. Aircraft structural aluminum alloys are precipitation hardened, where small nodules diffuse out of phase and bind the granular structure. This process continues even in ambient temperatures, and is accelerated by hot temperatures within ambient ranges. Once the nodules get too big, they cease to bind the granular structure and the metal is weakened.
 
the only concerns I would have are aerobatics or other high stress activities with some fabric coverings
 
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