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I think you fell for a trickster. "A small Fiat 126p, going 45 km per hour, was driven into a concrete wall. The bumper was not damaged. The driver wore no sea

by andor 6y ago

I think you fell for a trickster. "A small Fiat 126p, going 45 km per hour, was driven into a concrete wall. The bumper was not damaged. The driver wore no seatbelts. The inertial reaction, which should have thrown him onto the hood, did not ocur. The stopping distance was only 16 centimetres. Impossible? Yet hundreds of people in, and the stadium, and millions more on television. The use in all vehicles of the absorber of the energy, "Ecollision", can radically improve automobile safety." Regardless of the mechanism of energy absorption, if a vehicle is decelerated from 45 kph to 0 within 16 centimeters, there needs to be a way to remove the kinetic energy from the driver inside as well (seatbelts). If not, they will simply continue flying along at 45 kph, through the windshield. If the driver in this case was not wearing seatbelts, it's quite likely that the vehicle was not going that quickly. ``Lagiewka says, "The technical idea behind my buffer can be used in very many practical solutions. Another invention which I showed experimentally, is the brake. Connected to the axis on a Mercedes, the car stopped in one-quarter of the distance usually required".'' When braking, the limiting factor is usually not the brake mechanism itself (e.g. the disc brakes), but the interface between tires and the road. That's why cars have anti-lock systems.

carapace 6y ago
> I think you fell for a trickster. It's possible. I certainly haven't tried to replicate the mechanism. In the video you can see the driver does experience "the inertial reaction" when the car halts, at least it seems to me that he leans forward due to inertia at that moment. I think that description is just bad. (Or, of course, it was just a weird hoax.)
- andi999 6y ago
  If I do not calculate wrongly on my back of envelope, to brake from 10m/s (36km/h) in 10cm you need constant 50g acceleration on the driver... he certainly should feel that. Yes, it is a con.
  - carapace 6y ago
    Meaning no disrespect, I don't see why your "back of envelope" estimate (which you didn't actually share) should be given more credit than the video. Like I said, I think that written description is simply wrong. It wouldn't be the first time a journalist misreported the details of some technology, eh? I just watched the video again with the playback speed at 1/4 (thanks Youtube!) and at 0:46 ( https://youtu.be/z-h56N_A3rY?t=45 https://youtu.be/z-h56N_A3rY?t=45 ) when the car hits the bumper I can clearly see the driver lean forward due to inertia. Of course you still need to wear a seatbelt, this isn't magic. (You know on Star Trek how the Klingon disruptors make a person disintegrate, clothes and all, yeah? How does the disintegration process know to stop at the floor? What is it about the interface between boots and floor which stops the disintegration? Could you use that to make disintegration-proof armour?) I get what you're saying. I do. The point is not that the driver magically didn't feel inertia (he did, and you can clearly see it in the video) it's that the car didn't crumple. The kinetic energy given up by the stopping car went into the flywheel rather than into violent deformation of the physical structure of the car. I.e. it works (if it works at all, I don't deny that it might be a hoax) like a "crumple zone" without the crumple: > Crumple zones are designed to increase the time over which the total force from the change in momentum is applied to an occupant ... ~ https://en.wikipedia.org/wiki/Crumple_zone https://en.wikipedia.org/wiki/Crumple_zone
    - ric2b 6y ago
      > The point is not that the driver magically didn't feel inertia (he did, and you can clearly see it in the video) He clearly didn't experience 50g deceleration, he would have been sent flying through the windshield. What's more likely is that the car actually did take a lot more than 16cm to slow down to 0 m/s or that it wasn't going at 45km/h. I would bet on the second, the car looks like it's going at maybe 20km/h in the video. > The kinetic energy given up by the stopping car went into the flywheel rather than into violent deformation of the physical structure of the car. That's an interesting idea but if it ends up being less effective at protecting the humans inside I don't think most people will choose it over normal crumple zones.
      - 6y ago

by andor 6y ago

carapace 6y ago

> I think you fell for a trickster. It's possible. I certainly haven't tried to replicate the mechanism. In the video you can see the driver does experience "the inertial reaction" when the car halts, at least it seems to me that he leans forward due to inertia at that moment. I think that description is just bad. (Or, of course, it was just a weird hoax.)

andi999 6y ago
If I do not calculate wrongly on my back of envelope, to brake from 10m/s (36km/h) in 10cm you need constant 50g acceleration on the driver... he certainly should feel that. Yes, it is a con.
- carapace 6y ago
  Meaning no disrespect, I don't see why your "back of envelope" estimate (which you didn't actually share) should be given more credit than the video. Like I said, I think that written description is simply wrong. It wouldn't be the first time a journalist misreported the details of some technology, eh? I just watched the video again with the playback speed at 1/4 (thanks Youtube!) and at 0:46 ( https://youtu.be/z-h56N_A3rY?t=45 https://youtu.be/z-h56N_A3rY?t=45 ) when the car hits the bumper I can clearly see the driver lean forward due to inertia. Of course you still need to wear a seatbelt, this isn't magic. (You know on Star Trek how the Klingon disruptors make a person disintegrate, clothes and all, yeah? How does the disintegration process know to stop at the floor? What is it about the interface between boots and floor which stops the disintegration? Could you use that to make disintegration-proof armour?) I get what you're saying. I do. The point is not that the driver magically didn't feel inertia (he did, and you can clearly see it in the video) it's that the car didn't crumple. The kinetic energy given up by the stopping car went into the flywheel rather than into violent deformation of the physical structure of the car. I.e. it works (if it works at all, I don't deny that it might be a hoax) like a "crumple zone" without the crumple: > Crumple zones are designed to increase the time over which the total force from the change in momentum is applied to an occupant ... ~ https://en.wikipedia.org/wiki/Crumple_zone https://en.wikipedia.org/wiki/Crumple_zone
  - ric2b 6y ago
    > The point is not that the driver magically didn't feel inertia (he did, and you can clearly see it in the video) He clearly didn't experience 50g deceleration, he would have been sent flying through the windshield. What's more likely is that the car actually did take a lot more than 16cm to slow down to 0 m/s or that it wasn't going at 45km/h. I would bet on the second, the car looks like it's going at maybe 20km/h in the video. > The kinetic energy given up by the stopping car went into the flywheel rather than into violent deformation of the physical structure of the car. That's an interesting idea but if it ends up being less effective at protecting the humans inside I don't think most people will choose it over normal crumple zones.
    - 6y ago