Hey friends, Happy Wednesday!

Last week, I met my grad school friend after 4 years over lunch and we visited a history museum.

Let’s look at how Airbags work this week. I aim to write my newsletter issues in a way one can follow them while traveling on a bus, having a coffee, waiting for your food, etc. Let's jump in!

Tweet of the week

I’m sharing cool facts about gadgets and sharing behind the scenes of this newsletter every day on Twitter. And here is one of them for you. Follow me on Twitter to join the community :)

​https://twitter.com/ChendurSingaram/status/1678908342000054272?s=20​

Working Principle

Once the car begins to crash, a high current is passed to heat a thin resistant wire. Which causes a chemical guanidine nitrate filled inside the steering wheel to explode. This forms Nitrogen rapidly and fills the airbag in ~20ms, causing it to pop through the panels of the steering wheel. Thereby finally acting as a cushion and saving you!

How do Airbags work?

1. When a car crashes, it naturally decelerates a lot during the impact. An accelerometer sensor detects the amount of deceleration that the vehicle is experiencing during the crash. You can read how an accelerometer works from my first newsletter issue though it is not needed for this issue.
2. If a large deceleration is detected, then it can be confirmed that a crash has happened. Instantly after this, a current is passed through a circuit which causes a thin resistance wire to reach a very high temperature. This part of the circuit is within your steering wheel, which also has the chemical Guanidine Nitrate filled in a cylinder as seen in Figure 1. All this happens in 2 milliseconds.
3. Guanidine Nitrate explodes at this high temperature and undergoes a chemical reaction to form liters of Nitrogen, filling a nylon bag placed within the steering wheel.
4. As the Nitrogen fills the bag, it expands within 20-30 milliseconds, saving the head from crashing into the steering wheel by acting as a cushion. The airbag pops out through the front panel of your steering wheel by opening it up through the explosive force.
5. There are holes in the back of the airbag away from you, through which the air can escape causing the airbag, to eventually deflate. After which, you can move around and not be constricted. This is how airbags work!

Why do we need Airbags?

When we crash our car, our heads can hit the steering wheel or other parts with an enormous force due to inertia. This can lead to death. So we need some cushioning effect that reduces the impact and injuries we face on such occasions. Hence, we came up with an invention called the airbag. There are several variations of the same, and the above is the most common one that is being used currently.

Blog posts

My blog post S2E9 with more details on how Airbags work is coming out next week. I will notify you next Wednesday about the same. To recap, all my current newsletter issues are based on Travel and Transport, which is the topic for Season 2. I don’t convert all my newsletter issues into blog posts. I do expand on some of them and write them as blog posts. You can find all my previous blog posts here, down below.

Thank you for reading!

Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur

​​