Peak deceleration (should not be too high to avoid whiplash injuries)
and amount of energy absorbed  (by controlled plastic deformation) are,
I  think, materials selection criteria in the case of car chassis (in
addition to light-weight performance and all the rest).

I once read that the motor car started initially with a wooden chassis
as an "upgraded" carriage, one with a better power to weight ration
(engine instead of a or a couple of horses).  Wood was a viable
competitor for steel at that time also,  since steel at that time was
not a very advanced material.  During the last 10 odd years or so the
strength of some steels have been about trebled so that it can now
compete with aluminium for lightweight car construction, for example.

And one last comment to the aircraft saftey issue:  military aircraft
tend to be designed more innovative and somewhat less "safe" than
commercial (passenger or cargo) aircraft (composites earlier and in
larger quantities, computer controlled "automatic" flying rather than
manual etc) .  The statistics on the number of non-combat/accidental
military aircraft crashes  vs. commercial aircraft would confirm that, I
suspect.  The Star Fighter is a sad example of this.

Regards,
Ulrike Wegst


Recently, I had a chance to drive in one of the BMW USVs.  It has about
300PS (at less thanmore than four times, goes well over 200km/hour

Julian Vincent schrieb:

>At risk of being called a spoilsport, and much as I love aeroplanes (one of
>the guys in Bath Engineering said that most boys are interested in nature
>and model aircraft, and so to some extent it's chance as to whether you get
>ensnared by engineering or biology) I feel that the present discussion has
>got a bit out of hand!!
>
>I was relying on Jim Gordon's insight for my comments.  His thesis was that
>wood is the most efficient material (best specific properties for making
>durable structures) so that the Spruce Goose (underpowered though it might
>have been - problems in the metallic tradition, unless the engines used
>wooden pistons, which my dad said was a commonplace in the late '40s and
>'50s when 2nd-hand car salesmen were, as they say, unregulated) was the
>largest aircraft that could have been built at the time.  I should also
>point out to Jim (though he can obviously claim no responsibility) that the
>Morgan sportscar was banned in the US for quite a period because it uses so
>much wood in its body work, and this was considered to be an inferior
>material so that the car was deemed unsafe.  True or False??  Opinion here
>claims that the Morgan is safer because of the wood (though there is
>relatively little used).  Better to go for the Mini Marcos, which had the
>whole body shell made of formed wood.  Very light, durable and efficient!?
>
>Julian Vincent
>
>
>