This video shows a Volvo being crash tested.
On the roof of the car, toward the back above the rear window, there’s a row of some sort of small objects or devices which can be seen to “pop” or “fire” at the moment of impact. They look like firecrackers.
What are these? What is their function in this kind of test?
Smoke from the airbags, they use talcum powder to lubricate them.
Nope. The slo-mo shot clearly shows small explosive devices on the roof of the car toward the back.
I have to believe they are small blasting caps associated with safety signals. A visual check to see the timing and reaction of the sensors? They fire sequentially like side impact bags, maybe side impact bags would block the view of the dummies?
I’m thinking that they indicate the actual firing of the airbags within the car. A clear visual indicator of the actual airbag timing.
They must need some visual signal in addition to recording electronic sensor output. In slo-mo they appear to go off when the hood begins to pop up, that could be just coincidental though. Might just make it clear when the impact would set off the air bags when viewing the video alone, or make the crash look more impressive.
ETA: Ninja’d on the air bag timing.
I count five detonations, but only two airbags are deployed. I don’t see any side airbags.
Perhaps indicating different sensors within the airbag sequence?
Maybe they are indicating sensors other than airbags?
Those are pyrotechnic indicators or ‘squibs’ (from the above view you can see two rows of them firing starting at ~1:03) which provide independent timing and correlation to electronic signals. These are connected to shorting breakwires for various safety or crash indication functions. In addition to the airbags, there are numerous other pyrotechnically activated crash protection features on many modern cars including seatbelt pretensioners, active head restraint positioners, electrical and fuel system cutoffs, et cetera, and probably response instrumentation on passive features such as shearing bolts on the engine mounts, collapsing steering column, critical crush zones, et cetera.
Stranger
Excellent!