Wednesday, March 19, 2014

Physics Fail in Record-Setting Car Jump Attempt

Physics doesn't forgive - you obey the laws or you fail. It's a tough lesson that rally car driver Guerlain Chicherit learned as he tried to set a new record for the world's longest car jump. Check out the video below to see if you can tell what went wrong after he launched his modified Mini Countryman off the ramp.


Everything seems to be fine for the first two thirds of the flight. But then the sound of the engine dies and the car starts to rock forward. Those two things are intimately connected.

As the engine and the wheels slow, their angular momentum decreases. But angular momentum has to be conserved, so if the engine and wheels rotate slower, something else has to rotate faster. That something, unfortunately in this case, is the car.

It's possible Chicheritlost lost his nerve and let off the gas. The more likely problem, I'm guessing, is the setting known as the rev limiter. In many cars, including regular road-going Minis, if the engine spins too fast it can cause major problems. In order to prevent that, engineers program the engine management system to cut power above some set limit. Because Chicherit's wheels were spinning madly at the beginning of the flight, with nothing to slow them, there's a good chance the engine essentially cut off.

One way or the other, either the driver or the engineers overlooked some really basic physics of rotation, and the result was disastrous.

Fortunately, Chicherit, walked away with only minor injuries. At least they got the physics of the safety systems right.



5 comments:

  1. I don't think it's the rev limiter... if you hit the limiter and stay on the gas, the computer keeps the engine speed quite close to the limit. It doesn't kill the engine.

    Traction control or stability control could kill the engine speed, and there's certainly a loss of traction when you're flying through the air, but I can't imagine they left those systems enabled.

    What about fuel starvation from the fuel floating in the tank in free-fall?

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  2. Do you think it could starve that quickly?

    You're probably right about the rev limiter, but I recall that the rev limiter in my 2002 Mini didn't let me bounce off the red line like some cars do. Instead, it would cut out for annoying amounts of time. Still, I think your guess about traction control is right. In fact, Chevy engineers addressed this very problem with the Z/28 recently. They developed "flying mode" to ensure the traction control wouldn't kick in when the Z/28 was catching air at the Nürburgring. http://www.autoblog.com/2014/02/25/chevy-camaro-z28-flying-car-mode-video/

    They weren't worried about pitching forward during the brief flights, they were trying to prevent the car losing speed when it landed after the traction control shut everything down. Still, I think you're on to something - Chicherit's engineers need to develop a flying mode setting for the Countryman before they try the jump again.

    Thanks, Matthew.

    -Buzz

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  3. As you leave the ramp with the nose slightly upward the airflow should support that position. As long as your speed can maintain the needed air pressure to the cars underside the nose will stay up. Shorter jumps are over before the speed reduction lowers the nose. Once that air flow hits the windshield its all over. The angle of the windshield will deflect large amounts of air, forcing the nose down. This is a common problem in all record setting vehicle jumps. Even motorcycles suffer from this if the rider can't lean back to adjust for speed loss. Sometimes they even forget about this effect because their going so fast and things happen so quickly. The Mini should have had some additional aerodynamic modification to help maintain speed, and maybe even a small lip at its front to help keep the nose up. But that can also force the cars front end upward coming off the T/O ramp, it must be just right. And short of extensive wind tunnel testing you are left with trial and error crashing as the means of improvement.

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  4. We have found various types of zigzag jumping cars in rally games. Car rally games are quite amazing and it produce high voltage of terrific stunts; therefore specialist drivers are elected to drive in this rally games. I really feel amazing to watch this kind of stunts.

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  5. Really, it is amazing car jump attempt where physics fail in record. But it is a sad moment that physics has failed in record. I have liked the car jump event. Sometimes i enjoy the event and it is really enjoy full games for all of them.
    Chrysler

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