Re: B747 technical questions

Date:         01 Aug 97 04:04:17 
From:         faurecm@halcyon.com (C. Marin Faure)
Organization: Northwest Nexus Inc.
References:   1 2 3 4
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In article <airliners.1997.1561@ohare.Chicago.COM>, Andrew Goldfinger
<Andy.Goldfinger@jhuapl.edu> wrote:

> In article <airliners.1997.1484@ohare.Chicago.COM> Merlin Dorfman,
> dorfman@netcom.com writes:
> >     It's been a long time since I took thermodynamics, but if I recall
> >correctly after all these years, the pressure of any gas will increase
> >linearly with the absolute temperature if confined to a fixed volume.
>
> What about the 737?  During cruise, the tires are exposed to the outside
> environment.  Don't they get very cold, and lose pressure?

I'm not an engineer so I'm not qualified to get involved in the discussion
about the relative properties of air vs. nitrogren.  But the wheel wells
of all commercial jetliners, well, all Boeings at least, are not
pressurized or heated.  So I suspect that the tires in closed wells are
not much warmer than the exposed tires on the 737.  And as the tires on
the 737 are tucked up inside wells, I suspect they are not exposed to a
direct, supercooling airflow which would cause drag.  So the only
difference between the temperature of a 737 tire and a 757 tire is
whatever affect the relatively thin and unisulated gear door on the 757
might produce.

C. Marin Faure
  author, Flying A Floatplane