I watched on several movies the hero makes a powerfull kick on the front bumper and the cars airbug explodes. can something like that happen or does it only apply on steven seagal movies? :P

Many Thanks

Kostas Karabelas from Greece

Only in the movies.

There is actually a video of this in which an old lady makes an airbag explode in a car by hittinng the front bumper with her purse. As far as I can tell it is not edited. It's of some kids skateboarding then it zooms to show the intersection near them where this happens.

[quote]As far as I can tell it is not edited.[/quote]

How can you tell?

This would be a myth for them to test. If a person can't do it then how much force would it take? And are certain areas of the bumper more sensitive that the rest?

The airbag is triggered by an accelerometer that is "looking" for a rather large negative acceleration, usually in the high 20 MPH range. This sensor does not need to be mounted in the front bumper. I doubt that a kick from a non-Hollywood human could cause an airbag to deploy.

I was told by my uncle (car machanic) "If you can hit it hard enough at a sensor point, it will go off!!"

But you have to hit it damn hard. With a baseball bat or kick it direct on the sensor with a steel toe boot.

Whatever,,,, Its a myth, right!!!

Firstly, forgive my extremely long post, this is just my $0.02:

"The air bag system consists of three basic parts-an air bag module, crash sensors and a diagnostic unit. Some systems may also have an on/off switch, which allows the air bag to be deactivated."

"The crash sensors are located either in the front of the vehicle and/or in the passenger compartment. Vehicles can have one or more crash sensors. The sensors are typically activated by forces generated in significant frontal or near-frontal crashes. Sensors measure deceleration, which is the rate at which the vehicle slows down. Because of this, the vehicle speed at which the sensors activate the air bag varies with the nature of the crash. Air bags are not designed to activate during sudden braking or while driving on rough or uneven surfaces. In fact, the maximum deceleration generated in the severest braking is only a small fraction of that necessary to activate the air bag system"

"Air bags are typically designed to deploy in frontal and near-frontal collisions, which are comparable to hitting a solid barrier at approximately 8 to 14 miles per hour (mph) (13 to 23 km/h). Roughly speaking, a 14 mph (23 km/h) barrier collision is equivalent to striking a parked car of similar size across the full front of each vehicle at about 28 mph (45 km/h). This is because the parked car absorbs some of the energy of the crash, and is pushed by the striking vehicle.

Because air bag sensors measure deceleration, vehicle speed and damage are not good indicators of whether an air bag should have deployed. Occasionally, air bags can deploy due to the vehicle's undercarriage violently striking a low object protruding above the roadway surface. Despite the lack of visible front-end damage, high deceleration forces may occur in this type of crash, resulting in the deployment of the air bag.

"...airbag triggering algorithms...complex. They try to reduce useless deployments (for example, at low speed, no shocks should trigger the airbag to help reduce damage to the car interior in conditions where the seat belt would be an adequate safety device) and to adapt the deployment speed to the crash conditions. The algorithms are considered as very valuable intellectual property. Experimental algorithms may take into account such factors as the weight of the occupant, the seat location, seatbelt use, and even attempt to determine if a baby seat is present."

Source: http://en.wikipedia.org/wiki/Airbag

Given that everything I've read states the airbag deployment is due to sudden deceleration, it makes sense to me that you couldn't set it off unless you kicked really hard while the car was moving. Enough to stop the car from moving in fact. Thus, a kick, no matter how hard (given maximum human {not Hollywood} strength), should not set off an airbag while the car is sitting still.

Yeah I thought I read about it one time where a guy mad at the dealer hit 10 cars with sledge hammers to set them off.

If I recall my own internet research on it indicated that the car actually had to be moving. Now I can not say this for sure but I thought it was indicated by moving a speed sensor was a part of it, not a deceelarometer, in other words if the car was not moving you could hit it head on with a dump truck at 100 mph and the bag would not deploy.

[quote]Now I can not say this for sure but I thought it was indicated by moving a speed sensor was a part of it, not a deceelarometer[/quote]

I'm not an expert by any means, it quite possible the info I got from Wiki was wrong.

I think most anyone who's worked at a car dealership can tell you that this is possible, but only if the car is moving.

I worked at a Saturn dealership and people were always whacking the cars in one way or another because they saw the commercials about how Saturn's don't dent (polymer panels instead of metal), if you kick them, the dent pops immediately back out. (side note, just don't ever use anything pointy on them because they will puncture the panels )
But despite that abuse, no one ever set off an airbag by beating a stationary car.

However, a few times a lot attendant or a mechanic would be backing up or pulling in a car to a spot on the dealership lot with poor visibility at a low speed and one of us lowly sales team members would be standing where they wanted to park. They'd see one of us last minute, hit the brakes, and one of us (fearing being hit) would sort of kick out and hit the bumper with our foot. This did set off the airbag, twice that I witnessed.

[quote]There is actually a video of this in which an old lady makes an airbag explode in a car by hittinng the front bumper with her purse. As far as I can tell it is not edited. It's of some kids skateboarding then it zooms to show the intersection near them where this happens.[/quote]


that vid is staged so you know.

The sensors I worked with were either a ramp and steel ball or a pendulum style. There was normally one behind the dash center, and one or two out by the radiator. These were on the older single bag systems. It seems that no matter which peripheral sensor went off-the one behind the dash had to connnect also.

yea maby

cuse at 5mph it will go off(thats what i heard)

[quote]Now I can not say this for sure but I thought it was indicated by moving a speed sensor was a part of it, not a deceelarometer, in other words if the car was not moving you could hit it head on with a dump truck at 100 mph and the bag would not deploy.[/quote]

They are set off by g forces, the car does not need to be moving but it will have to move. If a dumptruck hits a car at 100 miles and hour the car is going to move and it should have enough of an impact to set of the triggers. Now if there were two dump truck and one hit from the front and the other hit from the back at the exact same time and with the exact same force the car wouldn't move and the bags shouldn't in theory deploy.

that video was staged. during fire-school we were tought that most (if not all) vehicles in production require the involvement of two or more sensors to deploy the airbag. he had just come back from some huge auto conferrence where the production companies were briefing emergency agencies on new safety standards and extrication guidelines. however there have been documented cases where a firefighter has bumped a vehicle after a crash and deployed the airbags hurting or is some cases even killing the occupant(s) or emergency personnel.

[quote]however there have been documented cases where a firefighter has bumped a vehicle after a crash and deployed the airbags hurting or is some cases even killing the occupant(s) or emergency personnel.[/quote]

I'd be interested to see that documentation.

i belive air bags work on a gravity sensor that when it sustains more that a number of G's then it goes off. so unless the hero moved the car at amazing speeds (20 mph in .3 seconds) then this is a dud effect, effects that don't happen in real life.

[quote]have been documented cases where a firefighter has bumped a vehicle after a crash and deployed the airbags hurting or is some cases even killing the occupant(s) or emergency personnel.[/quote]

Your right it can happen. The auto manufacturer won't promise the airbag won't go aff after a crash because they can't be sure that the electrical system or airbag system are still in perfect working order. During our training we were showed a video of a fire fighter who was assisting a patient in the passenger seat when the airbag deployed and hit him. So it can happen.