Re: Question about FAEs

jimp_at_specsol-spam-sux.com
Date: 09/25/04 

Date: Sat, 25 Sep 2004 05:20:26 +0000 (UTC)

In sci.physics Dan Bloomquist <EXTRApublic21@lakeweb.com> wrote:

> jimp@specsol-spam-sux.com wrote:
> > In sci.physics Bill Ward <bwardREMOVE@ix.netcom.com> wrote:
> >
> >>On Sat, 25 Sep 2004 00:01:34 GMT, Dan Bloomquist
> >><EXTRApublic21@lakeweb.com> wrote:
> >
> >
> >><snip>
> >>
> >>>It doesn't look like, at least the fuselage, has slowed much. So I would
> >>>have to say the ignition came from sparks. If the velocity was 450 fps,
> >>>I get a temp rise of 130f for water, so four times that for aluminum. (I
> >>>don't have the specific heat for kerosene but imagine it would be higher
> >>>than aluminum.) I'll have to confirm the velocity. But the kinetic
> >>>energy of any mass that contributes to the explosion would have to come
> >>>to a complete stop in the building. Apparently, only the wings could
> >>>have possibly contributed. That KE would go primarily into heating and
> >>>if there isn't enough heat, no contribution to an explosion.
> >>>
> >>
> >
> >>If you can figure out a way to keep a fuel fire from
> >>starting during a crash, you will have the eternal gratitude
> >>of a whole lot of people. All it takes is atomized fuel and
> >>a ignition source to turn a survivable crash into a tragedy.
> >
> >
> >>Even at landing speeds, a sliding impact will concentrate a
> >>lot of energy into a small region. Think of a chunk of iron
> >>against a grinding wheel. I don't see the relation of the
> >>specific heat of anything to the issue. It only takes one
> >>small spark, which happens quite often. Thats why even gear
> >>up landings on runways are always attended by a bunch of
> >>fire equipment.
> >
> >>I would be far more surprised if the fuel had _not_ ignited.
> >
> > Especially since it hid an office building full of AC power.
> >

> Hi guys,
> My second sentence:
> 'So I would have to say the ignition came from sparks.'

> No question that electrical wiring, or friction would ignite the fuel.

> The question has to do with 'the energy of the explosion'. Without a FAE
> you are just burning the fuel. The video:

> http://lakeweb.com/F77/images/f175-1.jpg

> What causes the fuselage, that should be free of what is happening in
> the building, to suddenly explode???

> Best, Dan.

Looks to me like the forwarding moving fuel caught fire, not exploded.

It looks a lot like a movie explosion; disperse a bunch of diesel fuel,
which is essentially what Jet-A is, and light it off. Lots of fire
and smoke but no pressure wave to speak of.

Real explosions don't have all that flame. Things just disappear. An
explosion would have taken off a big part of the building.

Maybe we're just dancing semantics here, but I fail to see any
inconcistency. 

-- 
Jim Pennino
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