"Robin Birch" wrote in message
...

During the second world war the Germans experimented with gliders to
shoot down bombers. At least one of these had a prone position. The
pilot had a chin rest to take the weight of his head.

I thought about that but thought maybe the structure to support the
chin-rest would then be in the 'flailing zone' in the event of an accident.
The next best thing would be something similar to the new neckbraces
motorsport drivers are using to restrain their heads in accidents, the HANS
safety device. A sort of carbon fibre neck brace.

http://jayski.thatsracin.com/schemes/hans.htm
http://www.guyons.com/hans.html

Ian