Re: Explosive decompression - how fast?

WaltBJ wrote:

> Note that the atmospheric pressure drops exponentially with
> altitude; the higher you go, the worse it gets, faster and faster.

I'm not sure that says what you mean it to say. Yes, pressure
continues to decrease as you ascend, and it's an exponential
function... but the pressure drop per unit height *decreases* with
increasing height. If you assume a scale height of about 8 km, than in
the first 100 m ascent from sea level you drop from 1.0 Atm to 0.9865
Atm, or a drop of 1.24e-4 Atm/m. But at 10 km altitude, the pressure
is dropping at a rate of just 3.56e-5 Atm/m. It gets worse, but in
terms of pressure, it gets worse slower and slower, not faster and
faster.

> BTW the flight attendant was propelled from the 737's cabin by the
> force of outrushing air, not sucked out.

You're going to have to be a little more specific here. The only thing
that can accelerate the body is a differential pressure force - the
question here is what is generating that force. A difference in the
bulk ambient pressure? A difference in the dynamic pressure on the
object due to wind? And what are the relative magnitude of these
forces? Nobody here doubts that a sustained 5 psi pressure difference
can generate significant unbalanced forces, but there's the question
of just what local pressure differential a flight attendant near the
middle of the fuselage would have been subjected to in that case due
to a simple depressurization, and the duration of those accelerations.
For instance, I've experienced pressure differentials larger than that
with no acceleration of my body... because they were too short in
duration (shock waves... although boy, did I feel queazy
afterwords :) ).

> I prefer pressurization and air conditioning and well-maintained
> aircraft...

Agreed :)

--
Brian Davis