Why are airbags not external?

Tesla

Tesla

Tesla

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Airbags are a good invention, they absorb a lot of force and have saved many lives.

Why are there not external airbags on cars? To help absorb impact forces.

I am guessing it hasn't been done for a reason?
 
Because by the time you've crashed the airbags wouldn't lessen any impact.

Crumple zones are there for this reason.
 
I guess because by the time the air bag is activated, the damage has already been done....i.e. the cars have already hit each other.

Also, it would take a much more substantial airbag to protect 800lbs of metal than 200lbs of human.

Edit: Beaten ;)
 
Obviously they wouldn't be deployed after the impact- that would be stupid.
A different release mechanism would be used.

I thought that much would have been obvious?
 
Tesla said:
Obviously they wouldn't be deployed after the impact- that would be stupid.
A different release mechanism would be used.

I thought that much would have been obvious?
Click to expand...

How would you do it though?
 
radar, and a computer to calculate the fact that physics will take over and you cannot avoid an object closing at X speed Y distance away?
 
Tesla said:
Obviously they wouldn't be deployed after the impact- that would be stupid.
A different release mechanism would be used.

I thought that much would have been obvious?
Click to expand...
Tell us how you would manage that and I'll retract my earlier statement.

If this mechanism can see into the future it'd be better employed telling people how to avoid accidents rather than lessening impacts.
 
Why? Surely it is obvious - no airbag is going to be able to alter the deceleration of a car! It can help slow a human being down gently because humans only have a mass of about 75kgs, a car moving isn't going to slow down much if it hits a bag of air! The airbag would have to be so massive and so strong that it would take up half the car.
 
I guess there's a load of safety issues involved, and I'd have thought a bag would be at risk of bursting and being ripped very easily by hard and sharp objects like cars. Also, I guess intenal airbags don't have to worry about an 80kg person hitting it at high force, I'd question how much energy an airbag for a 1200kg car would be able to effectively absob. The weight of the airbag and canister for that job would be quite high I'd have though.

Jaguar have a semi-external airbag system on thier XK, as part of the bonnet pedestrian impact protection, where the bonnet is raised on airbags to absorb the impact of a pedestrian's head.
 
There's a Lexus that detects unavoidable crashes and will prime the airbags, tighten seatbelts etc before an impact. I think it might be the GS that has PCS optional. I can't see why it couldn't deploy some kind of 'external airbag' :)
 
PMKeates said:
There's a Lexus that detects unavoidable crashes and will prime the airbags, tighten seatbelts etc before an impact. I think it might be the GS that has PCS optional. I can't see why it couldn't deploy some kind of 'external airbag' :)
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Cos priming them to go off is OK, but you'd have airbags going off all over the place without collisions happening :p
 
On this serious discussion of the practicalities of external airbags, I thought I would lighten the mood a tad.

externalairbagff0.jpg
 
Gilly said:
Tell us how you would manage that and I'll retract my earlier statement.

If this mechanism can see into the future it'd be better employed telling people how to avoid accidents rather than lessening impacts.
Click to expand...
As PMKeates has already said, their is a production Lexus using technology which could be adapted to this.
 
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