Car airbags are both a very simple concept and a marvel of engineering, replacing the bone-shattering impact of unforgiving plastic and steel with a relatively soft landing in a funky-smelling air cushion. This deceptively simple concept requires that the gas generator activates only when there is a crash and finishes filling the airbag in the milliseconds before the squishy human’s cranium with its soft filling attempts to occupy the same space as said airbag. This makes mad Aussie bloke [Turnah81]’s attempt at DIY-ing a car airbag a most daring proposition.
Rather than messing about with an IMU and microprocessors, he went low-tech with an inertial fuel cut-off switch. These are mechanical switches that hold a steel ball in place with a magnet until a sufficiently large force — like a crash — dislodges the ball and triggers an event. Usually, a switch like this cuts off the fuel pump.
After a bit of fun with a crash-test rig and the airbag of a salvaged steering wheel, a DIY airbag was assembled using a compressed-gas cylinder instead of the fancy gas generator, along with an electrically triggered valve. Here, you can already see why modern airbags use a gas generator, as it is simply far more compact.
For the bag itself, a pillow case was adapted, with the subsequent crash test — as pictured above — going about as well as you can imagine. After this, he tried a few improvements, like using a bin liner and detonating some fuel, but it seems that the gas generator is very hard to beat for producing a large amount of gas in very little time.
Meanwhile, the inertial cut-off switch turned out to be more than sufficient for this purpose, and it was also used to trigger the original airbag. Of course, with how cheap those off-the-shelf airbag units are and are tested to be fit for purpose, you’d never DIY them for actual use in a car unless you were stark raving mad.
Airbags have a checkered history. There are some places you shouldn’t try to save costs.
“Nice” clickbait thumbnail of something that didn’t happen. I’m giving the video a pass.
Agreed, please stop this nonsense
As far as I’m concerned all of this is the brainrot content for people who took a physics class.
Not solving any problems. Not sharing useful info. Just doing stupid things so that people (who I guess want to waste all day watching things that are only mildly entertaining and full of suggestions to buy stuff) click.
Do something real people. If you want to be entertained, then go find some good entertaining art that enriches your life and makes you think / feel differently. If you want to learn then go learn.
If you want to pretend to learn and be entertained while wasting large portions of your life and having your thoughts influenced by big corporations eager to keep taking your money, keep watching YouTube.
At least he’s complying with the ‘surprise butt sex face’ on thumbnail rule.
Also I disagree with the article premise.
Yes making your own airbag is a double diamond home hack. Approach with caution.
But…
A still live car airbag is all kinds of fun.
Launch things, move things, break things.
HackaDay should have a contest:
Best ‘hack’ based on a car steering wheel airbag.
Winner gets one free valet service at the ER.
Also:
42.
Explosions are art.
Blow something up today!
Even if it’s only a plastic bottle.
Minimum dry ice chunk available here makes one bottle financially dumb.
But change location, cops will likely be there inside an hour or three…six.
Don’t damage anything you don’t own…Excepting traffic cams etc…But camera, beware.
If you live out in the country, you can blow stuff up all day without any issues.
You can buy tannerite at a sporting goods store if you want to make a big boom as long as you’re not in one of the states that ban it. Just keep it away from anything that can produce shrapnel unless you want to win a Darwin award.
More importantly, any middle schooler can still make things go ‘boom’ in the burbs.
Match heads, then dry ice, then homemade (one reason 11YO boys buy saltpeter), eventually find way to reloading isle…WAAAAA…enlightenment.
I got my first fake ID intending to buy powder, was stopped by elder pyro, before I got into trouble.
Continued to pimp FFF outside the gun store (Hey mister, will you buy me 100ml of fuming nitric acid?)
Darwin aside, future engineers and hard scientists go through distinct ‘pyromaniac’ and ‘explosive pyromaniac’ psycho social development stages.
They have to do it.
A few are lost, but those who survive are stronger.
IMHO The fact that girls are so strongly discouraged from blowing stuff up while parents of pre-adolescent boys are almost (universally indifferent/worn out) has a lot to do with the lack of chicks in our workplaces.
Oh how I wish off-the-shelf airbag units and their triggering mechanisms were cheap. I smacked the nose of my car on track a couple years ago, and the cheapest replacement steering wheel airbag I could scrounge up was a salvaged one at close to $300. Luckily the passenger side airbag didn’t go off which is closer to $1,000. Nobody was in the passenger seat (the occupancy sensor that squawks at me for putting a bag of chips there can tell) so there was no reason to fire that one, but that didn’t stop it from firing the passenger-side seatbelt pretensioner, which meant that seatbelt mechanism had to be replaced as well. I was also lucky it didn’t similarly fire any of the rear pretensioners for no reason either. A mechanic who worked on the repairs told me about a Volvo sedan he’d worked on that set off all of its pretensioners due to a fairly light corner impact with only the driver in the car.
I’m also supposed to replace the SRS control unit that triggers all these systems (apparently it’s not guaranteed to work for multiple firings) which costs at least $100 for a salvage unit and is conveniently buried next to the heater core at the center of the car.
Isn’t $300 cheap compared to a trip to the ER in the US?
Yes, but for those of us not in the US who would come out of a crash without ever having to consider medical bankruptcy even if we don’t have health insurance from one of those “jobs” that are allegedly still attainable, it’s a pretty significant expense.
Also regarding the video where he asks if the wiring on the car-side of the airbag connector melts, yes it does, so if your steering wheel airbag goes off you’ll also need a replacement “clockspring” mechanism (which carries the wiring connections between the rotating steering wheel and the non-rotating dashboard). For my car I found one on eBay for about $100+shipping and taxes.
Well.. in 2020 I crashed my mtb on the side of a mountain causing a compound fracture and had to be airlifted to the hospital. Literal helicopter ride to hospital, a few days stay, one minor surgery, cast, and a very nice cane cost me…. well, the whole thing was about $2150, but that was what I’d already spent on the trip to the mountain.
See, on your average day of the week that ends in Y, I wake up at the crack of dawn, suffer through hoards of barely caffeinated zombies in rush hour interstate traffic to earn a living. Oddly one of the perks I get from this microsufferage is medical insurance.
That whole trip off the mountain in the medivac chopper, ER stay, surgery.. My out of pocket co-pay was $90 for using the ER.
so… no? $300 isn’t cheaper than a trip to the ER in America, provided you work for a living I guess? I digress.
They are cheap, if you know people in low places and aren’t picky about which airbag you want.
Back in the day, I traded a QP (4 ounces of flower, at time/place, maybe worth $200) for 10.
It all comes down to repairable wreck to worn out ratio.
At some point, for most car models, there are far more worn out cars then demand for repair parts.
Less true for big manufactures with lots of interchange.
But most steering wheel airbags include interior trim, some interchange limit.
Even with customers driving 20 YO good cars (like me).
Short version. If you want airbags for old Nissans, German cars or other ‘designed to be unmaintainable’ models, airbags can be had for cheap.
I know a group of junkyard clowns that filled a car shell with airbags wired in parallel and set them all off.
Before phone cameras were common in the junkyard, I’m still searching for vid.
Was told: None of them were the type to collect evidence on themselves.
Might need to be redone.
Security cameras likely only got a few parts flying into frame.
Old unwanted airbags are a disposal cost, JY owners prefer they disappear.
These things should only come as options.
I don’t like horseplay, and I have seen pranks where these things were put under sitting people. Break your own back.
I can see these things used against law enforcement. Say some nut is in a compound.
Your gear can now work against you.
Line either side of a narrow passage with these things—and you could crush the chests of five to ten folks single file if detonated.
Yet another reason to use an airbag to launch a bowling ball.
After you do that, you would never consider putting one under a person.
Seriously? WTF?
I’d kick their ass.
Right there, beatdown.
Likely go to jail.
But they would be the ones going to prison.
After they got out of the hospital.
More or less like anybody who tried to kill me and was still standing there flat footed…
Is ‘private ballistic research’ horseplay?
Retired safety restraints engineer here.
Airbags are tuned based on hundreds of factors. The first is the vehicle “pulse” or deceleration curve(s). This is how the airbag behaves in a number of crash scenarios.
Next is the distances from the bag to the occupant. This ai vehicle dependent. Seating / knee bolster.
The amount of propellant depends on the bag shape (vehicle dependent).
The propellant is also poisonous, and will ignite with the heat needed to open its canister.