Mythbusters and explosive decompression

Hi all,
I don't know if it was a rerun and has been thoroughly done over here,
but last nights episode of The Mythbusters 'busted' the explosive
decompression myth surrounding bullet holes in aircraft.
The guys sealed up a junked out cabin, pressurized it, then fired 9mm
bullets through first the skin and then a window. Nothing exciting happened.
Pretty interesting stuff.
They ended the episode by blowing a large hole in the fuselage. I was
out of the room when they set the charge so I don't know the size, shape,
etc. I did a bang up job of opening a hole.
My conviction of the miniscule damage to be caused by a sky marshall or
pilot popping off a few caps at a terrorists has been reinforced. The
diameter difference between a 9mm (.38") and a .44 Mag wouldn't make any
difference. Let's give the good guys the bigger cannon.

"Casey Wilson" wrote in message
...
Hi all,
I don't know if it was a rerun and has been thoroughly done over
here,
but last nights episode of The Mythbusters 'busted' the explosive
decompression myth surrounding bullet holes in aircraft.

It was a re-run. And it sure does show how ridiculous the debate over arming
pilots and sky marshals can be.

On Wed, 07 Jul 2004 16:37:56 +0000, Casey Wilson wrote:
The guys sealed up a junked out cabin, pressurized it, then fired 9mm
bullets through first the skin and then a window. Nothing exciting
happened. Pretty interesting stuff.

One factor that they neglected to account for is that many airliners fly
at speeds approaching Mach 0.85. I'd have to see a section of aluminum
skin with a bullet-hole in it staying intact in a transonic wind-tunnel
that was running about that speed before I put much stock in their
results.

-Luke

"Luke Scharf" wrote in message
news
On Wed, 07 Jul 2004 16:37:56 +0000, Casey Wilson wrote:
The guys sealed up a junked out cabin, pressurized it, then fired 9mm
bullets through first the skin and then a window. Nothing exciting
happened. Pretty interesting stuff.

One factor that they neglected to account for is that many airliners fly
at speeds approaching Mach 0.85. I'd have to see a section of aluminum
skin with a bullet-hole in it staying intact in a transonic wind-tunnel
that was running about that speed before I put much stock in their
results.

Also, if the test was done on the ground then of course nothing would
happen. It needs to done in a wind tunnel that is depressurized to simulate
30K feet.

Earl G

Gee what do you think the indicated airspeed is at M.85 at FL350?

Mike
MU-2


"Luke Scharf" wrote in message
news
On Wed, 07 Jul 2004 16:37:56 +0000, Casey Wilson wrote:
The guys sealed up a junked out cabin, pressurized it, then fired 9mm
bullets through first the skin and then a window. Nothing exciting
happened. Pretty interesting stuff.

One factor that they neglected to account for is that many airliners fly
at speeds approaching Mach 0.85. I'd have to see a section of aluminum
skin with a bullet-hole in it staying intact in a transonic wind-tunnel
that was running about that speed before I put much stock in their
results.

-Luke

Earl Grieda wrote:

Also, if the test was done on the ground then of course nothing would
happen. It needs to done in a wind tunnel that is depressurized to simulate
30K feet.

"Of course", "Needs", and "Simulate" is it?

The only necessity arising out of your post is that it be ignored. Your
simulation of comprehension of the subject won't fly.

The subject has been done to death here on a regular basis. Those who
are convinced they are in great danger from the presence of fire arms in
their world will never admit that the threat to the integrity of the
aircraft from gunfire in an airline cabin is minuscule, especially when
compared to the aftermath of a successful hijacking.

Read the archives of this discussion and allow the rest of us to
consider more interesting topics.


Jack

What difference would that make?

Mike
MU-2


"Earl Grieda" wrote in message
ink.net...

"Luke Scharf" wrote in message
news
On Wed, 07 Jul 2004 16:37:56 +0000, Casey Wilson wrote:
The guys sealed up a junked out cabin, pressurized it, then fired 9mm
bullets through first the skin and then a window. Nothing exciting
happened. Pretty interesting stuff.

One factor that they neglected to account for is that many airliners fly
at speeds approaching Mach 0.85. I'd have to see a section of aluminum
skin with a bullet-hole in it staying intact in a transonic wind-tunnel
that was running about that speed before I put much stock in their
results.

Also, if the test was done on the ground then of course nothing would
happen. It needs to done in a wind tunnel that is depressurized to
simulate
30K feet.

Earl G

On Wed, 07 Jul 2004 17:54:59 +0000, Mike Rapoport wrote:
Gee what do you think the indicated airspeed is at M.85 at FL350?

It looks like the calibrated[0] airspeed is around 325mph:
https://ewhdbks.mugu.navy.mil/mach-as.htm

I seem to remember that Mach 0.85 is transonic, so air is actually flowing
at supersonic speeds over some parts of the airplane (nose, wings, tail?)
and subsonic over others. All kinds of stuff that I don't know how to
predict happens then. Maybe someone here is an aerodynamicist who has a
better feel for compressible flow?

But, *that* is why I am skeptical of the Mythbuster's conclusion -- it
seems to me that supersonic/transonic airflow anywhere would be a
significant consideration -- especially if the flow happens to
be over the bullet-hole.

-Luke

[0] IIRC, "indicated" airspeed isn't valid above Mach 0.3 because of
compressibility effects -- but it has been quite some time since I took
that class (and I wasn't proud of my grade) so I could be very wrong. I
have just enough education on the topic to appreciate the expertise of
people who actually know what they're talking about!

My conviction of the miniscule damage to be caused by a sky
marshall or pilot popping off a few caps at a terrorists has been
reinforced.

Some years ago an airliner landed here in Richmond after having been shot by
someone on the ground. It was a completely coincidental thing where someone
shot into the sky and just happened to hit an airliner. The news report
showed the bullet hole; other than that the plane was fine.

If a bullet penetrated the skin of an aircraft, the plane could not have
been more than a couple of thousand feet high, and it would not be
pressurized.





"John Harlow" wrote in message
...
My conviction of the miniscule damage to be caused by a sky
marshall or pilot popping off a few caps at a terrorists has been
reinforced.

Some years ago an airliner landed here in Richmond after having been shot
by
someone on the ground. It was a completely coincidental thing where
someone
shot into the sky and just happened to hit an airliner. The news report
showed the bullet hole; other than that the plane was fine.