There is a difference, the neck must be immobilized between head and body as much as possible, but the deceleration on the head must be as slow as possible. If everything is immobilized, hitting the wall sideways, at relative slow speeds, before the crash structures begin to "work", it's like hitting a wall with your bare head without protection.bhall II wrote:They're already made from foam.Jolle wrote:...5cm of a soft material and then 10 cm of dense material?
http://s10.postimg.org/687hp3nu1/cockpi ... 00x349.jpg
Incidentally, safety tends to demand as much immobilization as possible, because that sort of flexibility in a crash causes everything from whiplash to basilar skull fractures (what killed Dale Earnhardt)....the neck isn't able to act as a flexible low speed impact cushion...
The "U" has foam indeed, but I suspect this is made for a high speed impact, just like a helmet. It's the differences you feel with a motorcycle helmet and a yellow safety helmet.