🚀 go-pugleaf

In article <37CACF0A.ABF2232C@bellsouth.net>,
  "M. W. Eglestone" <smsmike@bellsouth.net> wrote:
> Ron Miller wrote:
>
> > Wasn't it Boeing that did some kind of demo about the early 707 that
showed how
> > they could puncture the fuselage and they had a form of 'rip stop'
> > construction that prevented catastrophic propagation of the tear?
> > (direct design response to the Comet problems).
> >
> > Mr. Eglestone has my undivided attention as to his answer. (he has
> > knowlege and is on MY side of the agenda so I tend to trust his
> > description of what might happen. I would not have guessed that
> > aircraft skinning was brittle).
> <=======================================>
>
>  MWE: As for Boeing Aircraft, I have no idea what they did with the
> old Comet. I didn't start into heavy aircraft repair until 1965. I cut
> my teeth on the Boeing B-52D/E bombers and the KC-135 series tankers.
> Both of those aircraft used the standard 2024 -T3 series aluminum
> skins and structure. Highly conventional designs were used as well.
> The B-52 designs are so strong that we are still flying that series
> today. I would imagine that it's good for another 15 years with
> nothing more than electronics modifications and upgrades.

I think you must have not read the article you were replying to, because
you would have answered it had you read it and understood it.

You say you are familiar with the KC-135 tankers, which, IIRC, are based
on the same basic airframe as the 707, and should have been equiped with
any major enhancements to safety, particularly as KC-135's are much more
likely to be damaged in flight than 707's are, given that civilian
aircraft are normally going to go AWAY from potential threats, while it
may be neccesary for a tanker to stay near threats to refuel aircraft
that are returning from attacks on them.

On the other hand, it is also quite possible that the 707 didn't get
such a piece of technology as regular equipment and one was used as a
technology demonstrator to show that the thing works.

>  Aircraft skin isn't brittle enough to cause anyone to be concerned
> about sudden failure through normal wear and tear. However, there
> isn't any real economical way to design a pressurized fuselage that
> will withstand bullet punctures from the inside. It would be sort of
> stupid to even consider doing it; after all, what are the odds of it
> happening? Bullets hitting hydraulic and fuel lines? - the odds are
> against it. Depending upon the type of aircraft, the majority of the
> critical systems are under the passenger deck and along the sides of
> the cargo compartments. It would take a lot of well placed shots to
> hit most of those systems.

You seem to be missing a rather important point:  The expectation for
the ratio of incoming and outgoing holes resulting from cannon fire
against an aircraft from outside is at least as many entree points as
exit points, with a pronounced tendency for there to be more exit points
than entree points.  A 20 mm cannon shell is rather unlikely to be
stopped by anything INSIDE the aircraft if it get through the armour.
If the shell explodes inside the aircraft (not really all that likely,
given that they are fused with simple timing fuses, and would have to be
fired at just the right range to actually explode inside), the schrapnel
would tend to make more than one exit hole.


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