The Garage-Built Airbag That Faced a Real Crash Test

Aussie maker Turnah81 wanted to know whether an ordinary person could create a functional car airbag at home. He documented every step in a recent video and followed through with an actual crash test on a homemade rig. The results offer a clear window into both the ingenuity behind the build and the reasons professionals handle these systems.

Turnah81 began with the fundamental problem that all airbags must solve. In a crash, the car comes to a quick stop, but the driver continues forward because a bag must inflate and get in the way of items such as the steering wheel or dashboard before the driver’s body can close the space. Commercial versions use sensors, CPUs, and special inflators to achieve split-second timing, but he believed he could do better by stripping everything back.

The trigger was an inertial fuel cut off switch, which is what mechanics use to shut down the fuel pump after a severe impact. He set it up to close an electrical circuit when it received the correct kind of jolt. His concept lacked microcontrollers and accelerometers, instead opting for a traditional mechanical system that could be built in a workshop by one person. Next came the airbag module, which he salvaged off a wrecked car’s steering wheel. He got the gas generator, but he put the chemical one away and replaced it with a standard pressurized gas cylinder with an electronic valve. When the inertial switch activated, current flowed to the valve, opening it, and the gas simply pushed it into the bag. The cylinder generated a lot of pressure without causing any terrible explosive reactions like the chemical ones. Commercial gas generators are small, only a canister that can be hidden in a steering column, which saves space, but the compressed gas cylinder he used was large and cumbersome. When you see the entire thing in place, it becomes clear why manufacturers prefer the chemical approach; it simply will not fit neatly into a car.

He utilized a pillow case as the airbag material, with reinforcement at the stress areas and some careful sewing to prevent all that gas from rushing in. He put it all on a crash test rig, which is supposed to give you a realistic impression of what happens in a crash without putting a real automobile or person at risk. It works by detecting a collision and opening the valve, allowing gas to enter and inflate the pillow case. The whole thing moves quickly enough to see what’s happening on on camera, but it also demonstrates the practical reality, as it has some significant restrictions. Measuring the timing reveals that the bag inflates just as quickly as the actual thing, but the bag itself is different, as is the pressure profile, which is due to the fact that the gas is cool and expands slower.

Turnah81 conducted a number of studies and openly released the findings, with each trial supporting the premise that the system could be deployed on demand. The accompanying video captures that exact moment when the rig ploughs ahead and the bag whacks the bag where a driver’s chest would normally be. Although the findings are encouraging, the configuration demonstrates why a DIY airbag would always fall short of commercial kit. You have compressed gas cylinders that require constant pressure monitoring and temperature adjustments, which a basic valve cannot do on its own. If you set up the system on a cold winter morning, it will be underpowered. In warmer conditions, however, the bag will overinflate, rendering it incapable of providing adequate cushioning. The inertial switch detects head-on impacts well, but it may miss glancing blows or crashes at an angle, which commercial sensor suites can detect precisely.
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