Safe space habitat Was:the drive to explore

On Tue, 31 May 2005 12:41:57 +0100, in a place far, far away,
(phil hunt) made the phosphor on my monitor glow in
such a way as to indicate that:

On Mon, 30 May 2005 15:02:04 -0500, Earl Colby Pottinger wrote:
lal_truckee :

Just like properly designed and constructed up-to-code high rises don't
fall down when hit by an airplane.

And the planes flying into the buildings were not mistakes, we are talking
failures from 'dumb' mistakes, not planned destruction.

Plenty of planes *have* flown in buildings by mistake.

Not that many. The most notable case I can think of was the B-25 that
hit the Empire State in the fog, during the war. It did relatively
little damage. It's very difficult to imagine, in an era of modern
navigation technology, a fully-fueled wide body (which was what it
took to take down the twin towers) hitting a building accidentally.

: lal_truckee
: The building codes in place did say something about the fireproofing on
: the steel; but the owner/builder of record was the Port Authority who
: were apparently exempt from code, and took shortcuts. It's all there in
: the reports; I wonder why it doesn't get much paly in the press?

In the analyses I saw which mentioned that issue, the conclusion was
that no plausible amount of fireproofing on the internal structural
members would have helped much. If you raise the temperature of the
entire area high enough to weaken the steel, it doesn't matter if there
are no flames right ON the girders. And slowing down the heat transfer
into the girders, while a good thing, isn't a sufficient thing for a
prolonged, high-enough-temperature fire.


Wayne Throop http://sheol.org/throopw

Rand Simberg wrote:
Not that many. The most notable case I can think of was the B-25 that
hit the Empire State in the fog, during the war. It did relatively
little damage. It's very difficult to imagine, in an era of modern
navigation technology, a fully-fueled wide body (which was what it
took to take down the twin towers) hitting a building accidentally.

An El Al 747 freighter had the number 3 engine fall off the wing and
take the number 4 engine with it, and ended up crashing into an
apartment building. Not sure how much fuel they managed to dump before
the crash, but a 747 qualifies as a wide body in any event.

-jake

: "Jake McGuire"
: An El Al 747 freighter had the number 3 engine fall off the wing and
: take the number 4 engine with it, and ended up crashing into an
: apartment building. Not sure how much fuel they managed to dump before
: the crash, but a 747 qualifies as a wide body in any event.

But does "falling on" qualify as "flying into"? Well... "making a
catastrophic landing on" may not be "falling" exactly, but still.
The two seem a bit distinct.

Though I suppose if you just consider flying as
"falling and missing the ground"...


Wayne Throop http://sheol.org/throopw

Rand Simberg wrote:
An El Al 747 freighter had the number 3 engine fall off the wing and
take the number 4 engine with it, and ended up crashing into an
apartment building. Not sure how much fuel they managed to dump before
the crash, but a 747 qualifies as a wide body in any event.

I should have added the words "at full cruise speed."

Would the results have been appreciably different at less than full
cruise speed? Clearly, the chemical energy in the fuel tanks was much
greater than the kinetic energy of the plane, and I was under the
impression that it was more the wide dispersion of the jet fuel than
the gross physical damage caused by the impact that brought the towers
down.

-jake

On 2005-05-31, Rand Simberg wrote:

Plenty of planes *have* flown in buildings by mistake.

Not that many. The most notable case I can think of was the B-25 that
hit the Empire State in the fog, during the war. It did relatively
little damage. It's very difficult to imagine, in an era of modern
navigation technology, a fully-fueled wide body (which was what it
took to take down the twin towers) hitting a building accidentally.

We've certainly managed to ensure that something like the B-25 crash
either needs multiple failures or deliberate malice/incompetence, yeah.
Accidental controlled flight into a building, outside of stunt flying
gone wrong or military low-level work ditto, is probably implausible.

It is worth noting, though, that discussing an impact big enough to take
down the WTC is pretty much sticking to the upper end of the scale -
causing the same level of destruction on, say, a twenty-storey apartment
building wouldn't need it to be a fully laden aircraft, probably
wouldn't need it to be a widebody, nor would it require it to be going
at full cruising speed.

Most buildings are probably going to be totalled by, say, a 727 losing
an engine on approach and smacking into them. Which is unlikely, but
certainly not implausible; anyone have an idea how many accidents near
airports have lead to buildings being impacted and destroyed?

--
-Andrew Gray

On 31 May 2005 10:43:29 -0700, in a place far, far away, "Jake
McGuire" made the phosphor on my monitor glow in
such a way as to indicate that:

Rand Simberg wrote:
Not that many. The most notable case I can think of was the B-25 that
hit the Empire State in the fog, during the war. It did relatively
little damage. It's very difficult to imagine, in an era of modern
navigation technology, a fully-fueled wide body (which was what it
took to take down the twin towers) hitting a building accidentally.

An El Al 747 freighter had the number 3 engine fall off the wing and
take the number 4 engine with it, and ended up crashing into an
apartment building. Not sure how much fuel they managed to dump before
the crash, but a 747 qualifies as a wide body in any event.

I should have added the words "at full cruise speed."

In article .com, Johnny1a
says...

A couple of things occur to me:

1. Space travel by its very nature involves the potential for
high-velocity-difference impacts. Part of the key to habitat safety
would involve enforceable (and enforced) traffic rules, i.e. some
orbits are forbidden, that could readily intersect the orbits of the
habitats, no 'counter-orbital' trajectories allowed that could easily
come near the habitats, that sort of thing).

Air travel involves the potential for impacts at sufficient velocity
difference to wreck the vehicles involved, kill everyone on board, and
damage or destroy all but the heaviest fixed structures that might get
in the way. Furthermore, this potential will manifest within minutes
of any critical failure of flight systems, whereas an orbital vehicle
that goes dead will most likely remain in a very boring orbit for a
very long time.

In spite of this, we have bush flying in Alaska, the Northwest Territory,
the Australian Outback, and so forth. Which have air traffic control
systems and regulatory regimes, yes, but sense of perspective please.


You'll need something like the U.S. Space Command systems keeping track
of everything in the sky, and the feed would need to be pubically
available, or at least open to the authorities planning for safety.

Wake me up when the effective population density of outer space reaches
that of Alaska.


2. Since disabling safety features is a human constant, for high risk
situations the safeties need to be, where possible, passive, so that
they _can't_ easily be disabled.

Mechanical interlocks rather than software controls, physical barriers
and locks that have to be physically removed, things like that.

Fortunately, pressure hulls are as passive as you can get, and that's
most of your immediately critical risk exposure right there.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *

On 31 May 2005 12:00:34 -0700, in a place far, far away, "Jake
McGuire" made the phosphor on my monitor glow in
such a way as to indicate that:

Rand Simberg wrote:
An El Al 747 freighter had the number 3 engine fall off the wing and
take the number 4 engine with it, and ended up crashing into an
apartment building. Not sure how much fuel they managed to dump before
the crash, but a 747 qualifies as a wide body in any event.

I should have added the words "at full cruise speed."

Would the results have been appreciably different at less than full
cruise speed? Clearly, the chemical energy in the fuel tanks was much
greater than the kinetic energy of the plane, and I was under the
impression that it was more the wide dispersion of the jet fuel than
the gross physical damage caused by the impact that brought the towers
down.

Clearly, the towers wouldn't have fallen from the impact alone,
because they didn't for a long time. But a slower collision might
have resulted in less fuel dispersal into the building, perhaps with
much of it (and the plane's wreckage) falling on the street below
(admittedly a nasty scenario in itself). It's hard to know.

Andrew Gray wrote:


Most buildings are probably going to be totalled by, say, a 727 losing
an engine on approach and smacking into them. Which is unlikely, but
certainly not implausible;

Pretty near impossible, I'd say... NOBODY flies 727s anymore

anyone have an idea how many accidents near
airports have lead to buildings being impacted and destroyed?

I live in San Diego... in the 70's we had a Cessna and a 727 get
together and fall on a populated area - wiped out any houses it hit,
and burned a whole bunch more... then in the 80's, we had a Navy
military aircraft (F14 or A6?) come down in an industrial area, it took
out part of a concrete building; but, amazingly enough, I think only
the pilot was killed.

A few years ago, some copycat yahoo flew a Cessna into a building down
in Florida - didn't do s**t but get himself killed. Same with that
freak who flew a plane into the White House... both of these planes
kinda just hung out of the building.

Then, there was that guy that caused the Soviet Union to "jump the
shark"... he din't even have to hit a building, just landed in Red
Square - but he ended up being the straw that broke the bear's back.

- Stewart

- Stewart