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How cold does it get when you depressurise during flight testing?

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How cold does it get when you depressurise during flight testing?

Old 9th May 2018, 11:24
  #1 (permalink)  
Thread Starter
Join Date: Apr 2003
Location: Sutton
Posts: 469
How cold does it get when you depressurise during flight testing?

I am really interested to know from a practical what kind of temperature drop you would get overall from the combination of loosing your warm air through the outflow valves coupled with the adiabatic heat loss. I guess it will vary with aircraft volume and OATs etc but any empirical experience would be much appreciated.
I have looked at the engineering responses to this question and calculating it mathematically seems to require computer simulations. Thanks in advance.
RMC is offline  
Old 10th May 2018, 10:12
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Chief Tardis Technician
Join Date: Jan 2001
Location: Western Australia S31.715 E115.737
Age: 66
Posts: 554
At 10.000 ft it gets pretty cold, esperienced it in a Herc may years ago on a test flight. Not only de-pressurised, but opened the rear door as well. Interesting to watch bits of hay, string ond other loose stuff disappear out the back.
Avtrician is offline  
Old 11th May 2018, 03:30
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Join Date: Apr 2002
Location: Nirvana South
Posts: 726
We once had to depressurise our CRJ when around FL200 after hail cracked the Copilot's windshield over Oklahoma. Can't say I noticed any appreciable drop in temperature even though we only had the usual Flight Test interior with just the Insulation bags rather than a fully paneled one. IIRC the ECS was still providing warm air, it just was being dumped rather than being retained.
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