Mythbusters Explosive Decompression Experiment

On Sun, 11 Jan 2004 21:13:28 -0800 "C J Campbell" wrote:

Now, that was cool!

Mythbusters pressurized an old DC-9 and fired a bullet through the wall to
see if it would cause an explosive decompression. It didn't. Then they fired
a bullet through the window to see if the window would shatter and cause an
explosive decompression. The bullet only made a small hole in the window
because the windows are made of shatter-proof plastic. No explosive
decompression.

I don't watch much TV but I admit I would have liked to have seen this.

Can you provide more detail on how they setup the test?

What was the cabin pressure? What was the pressure external to the
DC-9? Did they have a huge pressure chamber?

What about the temperature differentials? There's also a pressure
differential from the flow of air over the fuselage. Correct?
How did they simulate that?


R. Hubbell


Then Mythbusters put explosive all around the window to blow it out and
deliberately cause an explosive decompression. The crash test dummy,
"Buster," was damaged but was not sucked out the window. If he had been a
real person he would have been injured but probably lived. His arm was badly
damaged enough that a human arm might have been lost. So Mythbusters patched
everything up and used a shaped charge to blow out the whole wall. The
explosive decompression ripped the entire top off the fuselage and much of
the wall out, but the seats and the crash test dummy remained in the
airplane. I would guess that if the "Buster" had been a live human he would
have been seriously injured and possibly killed.

Mythbusters then talked about how strong these airplanes really are and
closed with photos of the Hawaiian Airlines plane that suffered an explosive
decompression similar to the one that the show created with a shaped charge.
The only person killed was a flight attendant who was pulled from the plane
by the airstream, but the passengers all survived.

I thought the show was fascinating. It really demonstrated the engineering
that goes into an airliner. Besides, I like watching things blow up. It must
appeal to my inner 12 year old.

--
Christopher J. Campbell
World Famous Flight Instructor
Port Orchard, WA


If you go around beating the Bush, don't complain if you rile the animals.

"R.Hubbell" wrote in message
...
| On Sun, 11 Jan 2004 21:13:28 -0800 "C J Campbell"
wrote:
|
| Now, that was cool!
|
| Mythbusters pressurized an old DC-9 and fired a bullet through the wall
to
| see if it would cause an explosive decompression. It didn't. Then they
fired
| a bullet through the window to see if the window would shatter and cause
an
| explosive decompression. The bullet only made a small hole in the window
| because the windows are made of shatter-proof plastic. No explosive
| decompression.
|
| I don't watch much TV but I admit I would have liked to have seen this.
|
| Can you provide more detail on how they setup the test?

They took a derelict DC-9 at an aircraft graveyard and plugged up the holes.
They had real trouble with the cockpit because the windows had been removed.
They tried to replace the windows with plywood cemented in with foam, but
the plywood proved to not be strong enough to allow pressurization of the
aircraft. It kept blowing out, sometimes spectacularly.

The pistol was mounted on a stand in the cabin and fired by remote control
using a servor cannibalized from a vending machine, of all things. The
handgun was a 9 mm automatic; it looked like a Glock.

The aircraft was pressurized using one of those giant ground starter units
designed for 747s, a huffer. They dumped huge sacks full of packing peanuts,
scattering them around the cabin to so that the airflow inside the cabin
would be visible. The bullet holes disturbed the airflow so little that even
the packing peanuts stayed where they were.

|
| What was the cabin pressure? What was the pressure external to the
| DC-9? Did they have a huge pressure chamber?

They calculated the pressure differential at 35,000 feet to be 8 lbs psi, so
they pressurized the interior to 8 lbs psi. As mentioned, they had trouble
doing this. The plywood in the cockpit could only stand about 6 lbs psi. At
one point the plywood blew out and ejected a cushion from the pilot seat
more than 125 yards. They finally ended up reinforcing it enough to
withstand the 8 lbs psi differential. I guess the lesson there is that if
you ever lose a cockpit window you can forget about restoring cabin pressure
by plugging it up with plywood.

|
| What about the temperature differentials? There's also a pressure
| differential from the flow of air over the fuselage. Correct?
| How did they simulate that?

The 8 lbs psi differential comes pretty close to the pressure differential
for an aircraft pressurized to 6,500 feet flying at 35,000 feet. After all,
the total weight of the entire atmosphere is only 15 lbs psi. If anything,
they erred on the side of increased pressure differential. A pound of air
psi is a pound of air psi, no matter what the source.

One thing I found interesting which they did not talk about was watching the
skin of the airplane inflate and become taught as the airplane was
pressurized.

Once they managed to induce an explosive decompression using the shaped
charge, the damage was incredible. The whole top of the fuselage was ripped
off and big chunks of the wall where the explosion was were missing. It
looked like those photos of the Hawaiian Airlines incident, only much worse.
I think it might have been possible to continue to fly the aircraft, but it
would have been very difficult, depending on how much damage the debris did
to wings, tail, engines and control surfaces.

Of course, to do that kind of damage a terrorist would have to somehow get a
shaped charge the size of a basketball onto the airplane, place it properly
up against the wall of the fuselage, and detonate it, all without being
noticed. In any event, a bullet will not do that kind of damage, unless the
bullet is some kind of anti-tank artillery round. It was obvious that any
handgun bullet is too small by several orders of magnitude to do any
significant damage. You could have pressurized that plane for space flight
and the result would have been the same. Well, no it wouldn't. That much
pressure would have started popping windows or something long before they
would have had a chance to fire their gun or set off their explosives. But a
bullet hole would not have made a measurable difference even then.

On Mon, 12 Jan 2004 23:37:03 -0800 "C J Campbell" wrote:


"R.Hubbell" wrote in message
...
| On Sun, 11 Jan 2004 21:13:28 -0800 "C J Campbell"
wrote:
|
| Now, that was cool!
|
| Mythbusters pressurized an old DC-9 and fired a bullet through the wall
to
| see if it would cause an explosive decompression. It didn't. Then they
fired
| a bullet through the window to see if the window would shatter and cause
an
| explosive decompression. The bullet only made a small hole in the window
| because the windows are made of shatter-proof plastic. No explosive
| decompression.
|
| I don't watch much TV but I admit I would have liked to have seen this.
|
| Can you provide more detail on how they setup the test?

They took a derelict DC-9 at an aircraft graveyard and plugged up the holes.
They had real trouble with the cockpit because the windows had been removed.
They tried to replace the windows with plywood cemented in with foam, but
the plywood proved to not be strong enough to allow pressurization of the
aircraft. It kept blowing out, sometimes spectacularly.

The pistol was mounted on a stand in the cabin and fired by remote control
using a servor cannibalized from a vending machine, of all things. The
handgun was a 9 mm automatic; it looked like a Glock.

The aircraft was pressurized using one of those giant ground starter units
designed for 747s, a huffer. They dumped huge sacks full of packing peanuts,
scattering them around the cabin to so that the airflow inside the cabin
would be visible. The bullet holes disturbed the airflow so little that even
the packing peanuts stayed where they were.

|
| What was the cabin pressure? What was the pressure external to the
| DC-9? Did they have a huge pressure chamber?

They calculated the pressure differential at 35,000 feet to be 8 lbs psi, so
they pressurized the interior to 8 lbs psi. As mentioned, they had trouble
doing this. The plywood in the cockpit could only stand about 6 lbs psi. At
one point the plywood blew out and ejected a cushion from the pilot seat
more than 125 yards. They finally ended up reinforcing it enough to
withstand the 8 lbs psi differential. I guess the lesson there is that if
you ever lose a cockpit window you can forget about restoring cabin pressure
by plugging it up with plywood.

|
| What about the temperature differentials? There's also a pressure
| differential from the flow of air over the fuselage. Correct?
| How did they simulate that?

The 8 lbs psi differential comes pretty close to the pressure differential
for an aircraft pressurized to 6,500 feet flying at 35,000 feet. After all,
the total weight of the entire atmosphere is only 15 lbs psi. If anything,
they erred on the side of increased pressure differential. A pound of air
psi is a pound of air psi, no matter what the source.

One thing I found interesting which they did not talk about was watching the
skin of the airplane inflate and become taught as the airplane was
pressurized.



That brings up another question (don't have to answer, just food for thought)
How many pressurization cycles did the DC-9 experience over its lifespan?




Once they managed to induce an explosive decompression using the shaped
charge, the damage was incredible. The whole top of the fuselage was ripped
off and big chunks of the wall where the explosion was were missing. It
looked like those photos of the Hawaiian Airlines incident, only much worse.
I think it might have been possible to continue to fly the aircraft, but it
would have been very difficult, depending on how much damage the debris did
to wings, tail, engines and control surfaces.

Of course, to do that kind of damage a terrorist would have to somehow get a
shaped charge the size of a basketball onto the airplane, place it properly
up against the wall of the fuselage, and detonate it, all without being
noticed. In any event, a bullet will not do that kind of damage, unless the
bullet is some kind of anti-tank artillery round. It was obvious that any
handgun bullet is too small by several orders of magnitude to do any
significant damage. You could have pressurized that plane for space flight
and the result would have been the same. Well, no it wouldn't. That much
pressure would have started popping windows or something long before they
would have had a chance to fire their gun or set off their explosives. But a
bullet hole would not have made a measurable difference even then.




They did a reasonable job of recreating the environment but we all know
how hostile things are at 35,000 and 600 mph and -35 degrees, where air is
less dense.


So the question is would any of us be willing to head up to 35,000, crank her
up to mach .76 and get out the Glock and let loose a few rounds??

Also suppose the bullet hits some wiring or hydraulics or fuel line, etc.


Not me.


R. Hubbell

"R.Hubbell" writes:

So the question is would any of us be willing to head up to 35,000, crank her
up to mach .76 and get out the Glock and let loose a few rounds??

Also suppose the bullet hits some wiring or hydraulics or fuel line, etc.


Not me.

I woudln't do it in a *car* either, though. It comes under the
heading of "negligible risk, *zero* gain" -- so why risk it?

Shooting through the wall between windows pretty much guarantees I
won't hit hydraulics, fuel line, etc.
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com http://www.dd-b.net/carry/
Photos: dd-b.lighthunters.net Snapshots: www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/

On Tue, 13 Jan 2004 23:42:02 -0600 David Dyer-Bennet wrote:

"R.Hubbell" writes:

So the question is would any of us be willing to head up to 35,000, crank her
up to mach .76 and get out the Glock and let loose a few rounds??

Also suppose the bullet hits some wiring or hydraulics or fuel line, etc.


Not me.

I woudln't do it in a *car* either, though. It comes under the
heading of "negligible risk, *zero* gain" -- so why risk it?

I think you've missed the point. It was to say to Cambell "how
confident are you with mythbsuters conclusion?" "will you bet
your life on it?"


Shooting through the wall between windows pretty much guarantees I
won't hit hydraulics, fuel line, etc.

See my other post.



R. Hubbell

--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com http://www.dd-b.net/carry/
Photos: dd-b.lighthunters.net Snapshots: www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/

"R.Hubbell" wrote in message |
|
| They did a reasonable job of recreating the environment but we all know
| how hostile things are at 35,000 and 600 mph and -35 degrees, where air is
| less dense.
|
|
| So the question is would any of us be willing to head up to 35,000, crank
her
| up to mach .76 and get out the Glock and let loose a few rounds??
|
| Also suppose the bullet hits some wiring or hydraulics or fuel line, etc.

The air pressure in an airliner is less than one atmosphere, no matter what.
At 35,000 feet you are talking half an atmosphere. Compare that to the tires
in your car. The airliner produces all of 8 lbs psi, less than a third of
the inflation of an automobile tire. All of this other stuff, 600 mph or
slight variations of air pressure along the fuselage, etc., is minuscule.

Mythbusters gave the hyperventilating pants wetters a bit of a reality
check -- and all they can talk about are minor factors that will not change
the results in any significant way. I don't care if you empty the entire
magazine into a window, you are not going to suck people out of the
airplane, the airplane is not going to go into some kind of dive, people are
not going to fly all over the interior of the airplane, the seats are not
going to be ripped from the floor, or any other Hollywood bull**** like
that.

"C J Campbell" wrote in message
...

"R.Hubbell" wrote in message |
|
| They did a reasonable job of recreating the environment but we all know
| how hostile things are at 35,000 and 600 mph and -35 degrees, where air
is
| less dense.
|
|
| So the question is would any of us be willing to head up to 35,000,
crank
her
| up to mach .76 and get out the Glock and let loose a few rounds??
|
| Also suppose the bullet hits some wiring or hydraulics or fuel line,
etc.

The air pressure in an airliner is less than one atmosphere, no matter
what.
At 35,000 feet you are talking half an atmosphere. Compare that to the
tires
in your car. The airliner produces all of 8 lbs psi, less than a third of
the inflation of an automobile tire. All of this other stuff, 600 mph or
slight variations of air pressure along the fuselage, etc., is minuscule.

Mythbusters gave the hyperventilating pants wetters a bit of a reality
check -- and all they can talk about are minor factors that will not
change
the results in any significant way. I don't care if you empty the entire
magazine into a window, you are not going to suck people out of the
airplane, the airplane is not going to go into some kind of dive, people
are
not going to fly all over the interior of the airplane, the seats are not
going to be ripped from the floor, or any other Hollywood bull**** like
that.

Yes, but evidently Hubbel is stuck on his Hollyweird delusions.

"C J Campbell" wrote in message
...

"R.Hubbell" wrote in message |
|
| They did a reasonable job of recreating the environment but we all know
| how hostile things are at 35,000 and 600 mph and -35 degrees, where air
is
| less dense.
|
|
| So the question is would any of us be willing to head up to 35,000,
crank
her
| up to mach .76 and get out the Glock and let loose a few rounds??
|
| Also suppose the bullet hits some wiring or hydraulics or fuel line,
etc.

The air pressure in an airliner is less than one atmosphere, no matter
what.
At 35,000 feet you are talking half an atmosphere. Compare that to the
tires
in your car. The airliner produces all of 8 lbs psi, less than a third of
the inflation of an automobile tire. All of this other stuff, 600 mph or
slight variations of air pressure along the fuselage, etc., is minuscule.

Mythbusters gave the hyperventilating pants wetters a bit of a reality
check -- and all they can talk about are minor factors that will not
change
the results in any significant way. I don't care if you empty the entire
magazine into a window, you are not going to suck people out of the
airplane, the airplane is not going to go into some kind of dive, people
are
not going to fly all over the interior of the airplane, the seats are not
going to be ripped from the floor, or any other Hollywood bull**** like
that.

How much more clearly can things be explained...to a troll?

On Wed, 14 Jan 2004 06:24:34 -0700 "Tom Sixkiller" wrote:


"C J Campbell" wrote in message
...

"R.Hubbell" wrote in message |
|
| They did a reasonable job of recreating the environment but we all know
| how hostile things are at 35,000 and 600 mph and -35 degrees, where air
is
| less dense.
|
|
| So the question is would any of us be willing to head up to 35,000,
crank
her
| up to mach .76 and get out the Glock and let loose a few rounds??
|
| Also suppose the bullet hits some wiring or hydraulics or fuel line,
etc.

The air pressure in an airliner is less than one atmosphere, no matter
what.
At 35,000 feet you are talking half an atmosphere. Compare that to the
tires
in your car. The airliner produces all of 8 lbs psi, less than a third of
the inflation of an automobile tire. All of this other stuff, 600 mph or
slight variations of air pressure along the fuselage, etc., is minuscule.

Mythbusters gave the hyperventilating pants wetters a bit of a reality
check -- and all they can talk about are minor factors that will not
change
the results in any significant way. I don't care if you empty the entire
magazine into a window, you are not going to suck people out of the
airplane, the airplane is not going to go into some kind of dive, people
are
not going to fly all over the interior of the airplane, the seats are not
going to be ripped from the floor, or any other Hollywood bull**** like
that.

How much more clearly can things be explained...to a troll?

You know Sixkiler there's some really good research that shows how a
positive mental attitude can bolster the immune system. And also that
a negative one can have adverse effects. Try to lighten up and enjoy
life and concentrate on good things not bad. Yes I am serious.

Don't knock it until you try it.

R. Hubbell

On Wed, 14 Jan 2004 01:46:31 -0800 "C J Campbell" wrote:


"R.Hubbell" wrote in message |
|
| They did a reasonable job of recreating the environment but we all know
| how hostile things are at 35,000 and 600 mph and -35 degrees, where air is
| less dense.
|
|
| So the question is would any of us be willing to head up to 35,000, crank
her
| up to mach .76 and get out the Glock and let loose a few rounds??
|
| Also suppose the bullet hits some wiring or hydraulics or fuel line, etc.

The air pressure in an airliner is less than one atmosphere, no matter what.
At 35,000 feet you are talking half an atmosphere. Compare that to the tires
in your car. The airliner produces all of 8 lbs psi, less than a third of
the inflation of an automobile tire. All of this other stuff, 600 mph or
slight variations of air pressure along the fuselage, etc., is minuscule.

Mythbusters gave the hyperventilating pants wetters a bit of a reality
check -- and all they can talk about are minor factors that will not change
the results in any significant way. I don't care if you empty the entire
magazine into a window, you are not going to suck people out of the
airplane, the airplane is not going to go into some kind of dive, people are
not going to fly all over the interior of the airplane, the seats are not
going to be ripped from the floor, or any other Hollywood bull**** like
that.




You still didn't answer the question though. Will you take a plane up
to mach .76, get out your Glock and fire some rounds off through the cabin
floor, walls, ceiling or any other random place? If a skymarshal is wrestling
someone hell bent on getting his gun the bullets would firing at all angles
in all directions.


There are simply too many factors that mythbusters didn't replicate
to convince me that it's safe to fire 9mm rounds through a fuselage
of an aircraft traveling mach .76 at 35,000 ft. where it's -35 degrees.

There's something else that comes to mind as well. I was reading a report
on the HA (Hawai'i Airlines) accident and they talked about the concussive
force that caused the large hole to open up. What happens is similar to
water-hammer in water supply lines. The hole has air rushing out thru it
at some very high rate then some object from the aircraft plugs the hole.
Suddenly all the air destined for the hole backs up behind that object
and that generates an extreme and instantaneous amount of force on just
that spot. Guess what happens next? A bigger hole appears and if it's not
big enough it will get blocked again and we have a repeat of the previous
concussive event. Until the hole is bigger than all loose objects.

I can't find that site, someone posted it here a while back.



R. Hubbell