Mike Ash wrote:
In article ,
Tom Duhamel wrote:

Gliders fly at lower altitudes, at lower speeds, in good weather
conditions...

Airliners fly in high altitude, high speed, low temperature, in
thunderstorms...

Don't think airliners fly higher. It's true that *on average* they do,
and they certainly collect *vastly* more time at FL360 than gliders do,
but gliders *do* collect time there. The current glider altitude record,
set in a composite glider, is over 50,000ft. I don't think low
temperatures or pressures have been seen to do anything bad to the
structure. A fellow did tell me once that a rapid descent can do bad
things to the gelcoat due to the temperature change, but that's a
separate issue, and I don't know if an airliner would even use that sort
of coating.

For speeds, that's really just a matter of increased structural strength
and stiffness, which means using more stuff or different shapes. The
question is how the composites tolerate load, which is well known. They
won't change their characteristics suddenly just because they're moving.

How good is composite when lightning strikes? Doesn't is explode or
something? I don't think it will conduct electricity, does it?

This one is a completely open question to me. No, they don't conduct
electricity as far as I know. In the one famous case of a glider getting
hit by lightning, the lightning traveled along metal control rods. The
rods superheated the air inside the wings, blowing the glider to bits.
Obviously this is not a desirable outcome for an airliner carrying 300
people and no parachutes. I can only assume that the smart engineers
working on this stuff have figured out a way to stop this from
happening, but I have no idea at all what that way would be.


Embedded conductive layers.

http://www.lightningtech.com/d~ta/faq1.html

--
Jim Pennino

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