If you have your head touching the canopy it cannot accelerate into the
canopy and hurt you.

Sure it can. If you hit a 3 G negative acceleration, not uncommon in heavy
ridge lift, the glider is accelerating down at 3G. Your head is trying to stay
where in one postion spatially, so the result is a force against the canopy
equal to the mass of your head times the G forces. The more dense your head,
the higher the force!

Jim Vincent
N483SZ
illspam