Post by Jaimie Vandenbergh Post by Greg Goss Post by J. Clarke
If there's no windshield there's no need for a cushion between the
passenger and the windshield. In any case hitting the windshield is seldom
They're designed to be weak when smacked from the inside partly for that
Post by Greg Goss
Right. But the cushion also holds the passenger in place while the
kinetic energy is dissipated slowly enough to survive. For that, the
cushion needs to stay in place. A bag of air isn't going to hold the
passenger in place if there's nothing behind it.
Airbags don't work like balloons or inflatable pool cushions, they
explode/absorb a human impact/collapse in under a second and do all
their work at that moment of the crash. They'll happily break your nose
and glasses and eardrums if needed to stop you smashing your head on
things. They're also tethered to the location they explode from,
securely enough to do that protection.
Cheers - Jaimie
I've read a bit more: it seems that after all,
the thing with air bags and windshields is that
the passenger bag was, or is, or might be built
to be fired towards the windshield, not the
passenger, who gets it on the rebound from
the windshield. As for how fast - I'll look
for videos. In a crash in a TV comedy show,
the air bags remain inflated long enough for
the audience to appreciate and laugh at the joke.
In real life, the first impact is not necessarily
the end of the incident.
The U.S. roof crush resistance standard - for
car with windshield in place - in successive
versions, is called FMVSS 216. Glass companies
talk about the importance of the properly fitted
windshield, which doesn't prove it but that
doesn't justify not having one. Some safety
campaigners say that the 2012 standard is
unsatisfactory specifically because the windshield
resists force squashing the car in a test, but
not in an actual roll-over crash: there's also
concern about the direction in which force is
applied in the test.