I think you have a point. I just spoke to one of my students who does
failure analysis of aircraft parts. They have giant machines that pulls
and pushes a part until it breaks, and they take high speed photos
during the process for analysis. He seems to think that the tank being
full or not can go either way depending on the construction. In an
empty tank, the impact will tend to buckle the walls until the
structure collapses. In a full tank the fluid will equalize the forces
on all contacting surfaces, and will cause it to fail at the weakest
point, usually a weld joint. He seems to think that on welded
structures a full tank is probably worse, in agreement with Paul's
message.
--- Jeremy Davey <europaflyer_3@msn.com> wrote:
> <europaflyer_3@msn.com>
>
> Andrew,
>
> I think Paul is right. There is a direct parallel in the mechanism he
> refers
> to in the Concorde accident in Paris - there debris hit the very full
> tank
> causing a segment of the wall to be blown out at the weakest point.
> It might
> not have happened had the tanks not been brimmed.
>
> With the Europa tank, what the Land Rover unscientific demonstration
> tells
> us is that the tank can flex hugely without splitting. What any
> materials
> scientist will tell us is that the material will have a limit to the
> tension
> loads it can take: it is possible for a full tank taking an impact to
> split
> in tension; that tension arises because the contents will not allow
> if to
> flex.
>
> Taking your can analogy: fill it with a dense foam (compressible) and
> throw
> it against a wall, hard. It will likely not split. Fill it with
> liquid and
> throw it similarly: it will likely split.
>
> If the above stands scrutiny, it does tell us that brimming the tanks
> "just
> because there is space so I might as well use it" is not always the
> wisest
> policy if that fuel is not required.
>
> Regards,
> Jeremy
>
> -----Original Message-----
> From: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com] On Behalf Of Andrew
> Sarangan
> Sent: 18 June 2007 04:01
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Fuel Tanks
>
> <asarangan@yahoo.com>
>
> I am not sure about that theory. It is easier to crush an empty soda
> can than a full one. Air is more compressible than liquid. When a
> full
> tank is impacted, the liquid will transfer that energy to all
> surfaces
> with little or no compression. A partial tank on the other hand will
> compress until the air inside is squeezed to match the liquid. By
> then
> the tank might have undergone enough bending stress to break it.
> Again,
> just a theory.
>
>
>
> --- Paul McAllister <paul.mcallister@qia.net> wrote:
>
> > <paul.mcallister@qia.net>
> >
> > Hi all,
> >
> > I recall watching Ivan Shaw's impromptu demonstration of a
> Landrover
> > driving
> > over a Europa fuel tank.
> >
> > I remember thinking at the time, wondering if it would fare as well
> > if it
> > was full of liquid. I suspect that the hydraulic pressure would
> > easily
> > rupture the tank, no matter what it was constructed of.
> >
> > I would offer up a hypothesis that a full tank in a Europa that was
> > subjected to a high G load would rupture, but one that has had fuel
> > burnt
> > off would have sufficient airspace in it that could be compressed
> and
> > not
> > cause the tank to burst.
> >
> > Just a theory.
> >
> > Paul
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
>
>
>
>
>
>
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