Re: FAA To Finally Ditch Floppy Disks & Win-95

Charlie Gibbs <cgibbs@kltpzyxm.invalid> wrote:

On 2025-06-16, c186282 <c186282@nnada.net> wrote:
 

On 6/15/25 10:19 AM, Rich wrote:
>

c186282 <c186282@nnada.net> wrote:
>

   There ARE circumstances where 'natural fibers' CAN outperform
   plastics - esp at very low temperatures where the plastics become
   more brittle.

 
And just what do you have at altitude?  Very low temperatures, just
exactly what you state "where the plastics become more brittle":
 
https://matmake.com/properties/standard-atmosphere.html
 
10k-20k feet -> -60C
25k feet (typical passenger aircraft cruse altutude) -> -50C

 
You missed the notation on the chart: those altitudes are in
meters, not feet.

Ah, yes, I did miss that.  Compensating for that, the typical
commercial flight altitudes see temps ranging from about -30C down to
what looks to be about -57C.

Basically, the standard atmosphere specifies a temperature of 15C at
sea level, decreasing by 2C per 1000 feet up to the tropopause, which
is typically around 35,000 feet.  There the temperature levels off at
about -55C and stays there up to well beyond the service ceiling of
any aeroplane (as opposed to rocket).  In real life these numbers
vary, and aviation weather stations provide forecasts of actual
conditions in the current time frame.
 
Still, given that airliners cruise at 25,000 to 40,000 feet,
they're exposed to some pretty intense cold.

Cold enough that nylon ties in unheated areas will be experiencing
chill levels often dangerously close to their brittle point.

   You DO have a fair point here.  Not ALL plastics get brittle, but
   maybe Nylon does.  In any case I'm sure they're not using hemp
   string for aircraft harnesses anymore.

 
Yesterday I felt a something catching while moving the controls in
our small plane.  I found that various bits of plumbing behind the
panel had shifted to where they were touching things they shouldn't. 
Time to get out those good old nylon zap straps and tie things back
where they belong, just like the mechanics do.  Mind you, we don't
get much above 10,000 feet...

If they were behind the panel, that would still be in the portion where
the temp is not -30C to -60C (otherwise you'd be rather chilly and
uncomfortable yourself).  So still plenty of safety margin left before
brittleness would become a factor there.