Tom Gardner wrote:

And absorbing energy the principal reason why, in a crash, it is
better to be in a steel vehicle than aluminium, and GRP or composites
are worst of all.

Design of the structure is extremely important, as are the other safety
devices, so a blanket statement like this is wrong. Take a look at the
large variations in crash protection provided by similar all-steel
vehicles - if it were primarily materials used, there wouldn't be such
differences.

After all, we sit on energy absorbing cushions for a
very good reason.

The reason is the very limited crush space available below the seat, not
the materials used. The manufacturers work to improve this situation by
providing taller landing gear designed to collapse in a controlled
fashion, to absorb as much energy as possible. This one reason why most
(maybe all - I don't know of an exception) flight manuals tell you to
never land gear down.


--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org