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43 Comments
- brianhood, on 05/18/2009, -0/+41no video?¯\(°_o)/¯
- wornlater, on 05/18/2009, -4/+17buried for no video
- joshthegreat200, on 05/18/2009, -1/+12Cant really call it "defying" gravity by doing a loop the loop when a hotwheels car can do it.
- leftfield, on 05/18/2009, -0/+11We've been there, done that. In the 60's http://www.youtube.com/watch?v=81gn2oLeC_U
- Avagad, on 05/18/2009, -0/+5I think you two are over complicating things but I don't want to throw my hat in...
But I will leave this here:
http://xkcd.com/123/ - mojoe1185, on 05/18/2009, -1/+5No the article is correct, and you are sort of correct, the centripetal force IS acting towards the center of the loop. But what you are forgetting is that that force is constantly accelerating the car toward the center also. This constant acceleration on the mass of the car gives an opposite but equal force back onto the loop. This is what is usually confused as centrifugal force. :-)
Physics works!! - Gusbob, on 05/18/2009, -1/+5"Steve Truglia successfully completed the stunt by precise control of centripetal - often incorrectly known as centrifugal - force.
The Toyota had to be travelling fast enough that the centripetal force generated by its circular motion 'offset' the downward pull of gravity."
Last time I checked centripetal force was an inward pulling force? Inertia is what is offsetting the pull of gravity and centripetal force. Since the car is in an accelerating (non inertial) frame, pseudo forces like centrifugal force (inertia really) are required to maintain validity of the classical laws of physics. - Nicoon, on 05/18/2009, -0/+4How is this defying gravity?
- ayeroxor, on 05/18/2009, -0/+3I'll feel okay saying "centrifugal force" until they rename centrifuges "centripets".
- Vodd9, on 05/18/2009, -0/+3We need more real-life Trackmania.
- bigplrbear, on 05/18/2009, -0/+3psh, he's got nothing on Sonic
- MacBandit, on 05/18/2009, -0/+2Although true most of us knew he was referring to a G-Suit.
http://en.wikipedia.org/wiki/G_suit - 1x253, on 05/18/2009, -0/+2I'll be more impressed if he skydives from space.
- spritom, on 05/18/2009, -1/+3Just as long as he doesn't wear a red suit!
- phibit, on 05/18/2009, -0/+2I came here just to say that... This stunt still operates within the laws of gravity, unlike what the title suggests.
- i4ybrid, on 05/18/2009, -0/+2I'm no physicist, but it sounds hard from what's in the article:
"The Toyota had to be travelling fast enough that the centripetal force generated by its circular motion 'offset' the downward pull of gravity. This required the stuntman to enter the loop at exactly 37mph, immediately change out of gear and slow to 16mph as the vehicle swung round the top." - screensnot, on 05/18/2009, -1/+2I don't want to take anything away from the driver, but I am more impressed by the engineering. And
the engineer didn't even get his name mentioned. - tmacfan123, on 05/18/2009, -0/+1This guy's crazy...apparently his next "challenge" is going to be skydiving from space...
- 1x253, on 05/18/2009, -0/+1I'm filled with the urge to buy Hot Wheels. Saaaaayy, do you think there's any connection between the stunt man and the Hot Wheels company? NevermindI'mgoingtogogetsomehotwheelsseeyalater....
- Nairebis, on 05/18/2009, -0/+1I don't get this. I could see *maybe* slowing down as you come out, just because you don't want to go too fast and lose control, but entering the loop at an exact speed? That makes no sense at all.
Or to put it another way, what happens if you go too fast? You would just push harder on the loop and come out a bit faster.
I suspect the reporter heard "has to go a minimum of 37 mph" and wrote "has to go precisely 37 mph."
And why would you be shifting gears in the loop? That's just stupid. If it were me, I'd just keep flooring it until I was out of the loop, then hit the brakes. - diggnidy, on 05/18/2009, -0/+1its scientific bitches
- cr42yr1ch, on 05/18/2009, -0/+1Amateur for using a circular loop, everyone knows that non-constant curvature allows for higher speeds entering the loop (within reasonable g-forces) so allowing a larger loop size.
There is a very good reason rollercoasters don't have circular loops. The first ever loop-the-loop rollercoaster had a circular loop and it broke a lot of people's collar bones. - fadetoone, on 05/18/2009, -0/+1Is the submitter Romulan?
- Peko, on 05/18/2009, -2/+3Weird he didn't go for a clothoid loop. [Yeah, I had to google for the name too =)]
- 1x253, on 05/18/2009, -0/+1I'm not a physicist, but I imagined as much b/c I'm a roller coaster junkie and I've never required a flight suit for the loops on the coasters on which I've coasted. The article is a pretty sensational telling of the stunt.
- jazduck, on 05/19/2009, -0/+1Just did some quick math on this - feel free to correct me if im wrong.
m = 1000 kg (rough guess for a small car as it doesnt specify)
r = 6.1 m
v = 16.5 m/s
At the bottom of the loop at 16.5 m/s
ΣFy = (mg + mv^2) / r
ΣFy = (1000*9.8 + 1000*16.5^2) / 6.1
ΣFy = 46237.7 N
F = ma
a = F/m
a = 46237.7 / 1000
a = 46.23 m/s^2
g = 46.23 / 9.8
g = 4.7
So unless im wrong 4.7 g's is the maximum encountered. Not enough to make your average tensed up human grey or black out. Also sustained g forces are what typically leads to pilot blackout, a fast maneuver such as a snap roll which is a high g but very quickly executed maneuver affects you less than a sustained lower g maneuver such as a loop or steep turn.
Feel free to correct, but sounds like they've really hyped up the whole g force thing, again. - bot001220, on 05/19/2009, -0/+1http://sittingnow.co.uk/wp-content/uploads/2008/03 ...
- Hnnnnnghhh, on 05/18/2009, -0/+1What monster writes an article about this without a video?
- willhirsch, on 05/18/2009, -0/+1The Mail might not be interested, but Cambridge University Engineering Department is... http://www.eng.cam.ac.uk/news/stories/2009/Fifth_G ...
Hugh Hunt is a legend. - 1x253, on 05/18/2009, -0/+1willhirsch
I believe you, but I'm curious where you got the info from. - Witchdoktor, on 05/18/2009, -0/+1http://www.youtube.com/watch?v=lrBZeWjGjl8
- MacBandit, on 05/18/2009, -0/+1It only requires 1g to pull a loop.
- willhirsch, on 05/18/2009, -0/+1My guess is that a clothoid loop only minimises G-forces if you allow downwards Gs at the top, i.e. your rollercoaster can cling on at the top. Whatever it is, the guy who oversaw it is senior lecturer in mechanical engineering at the University of Cambridge, and I'm pretty confident he knows what he's doing.
- 1x253, on 05/18/2009, -1/+1Yeah, I understand your point. On the other hand if he had missed a decimal point in his calculations his name probably wouldn't have gotten mentioned either.
- 1x253, on 05/18/2009, -1/+1I was wondering to myself if he might have used a flight suit to help him deal with the G Forces... until I found out his top speed was 37mph and his slowest was 16mph. Noticeably they left out how many G Forces were achieved.
- willhirsch, on 05/18/2009, -0/+0http://www.eng.cam.ac.uk/news/stories/2009/Fifth_G ...
If he went too fast, he'd black out. - willhirsch, on 05/18/2009, -0/+06G... http://www.eng.cam.ac.uk/news/stories/2009/Fifth_G ...
Flight suits are for air pressure, not for G-forces - Nairebis, on 05/18/2009, -3/+3It definitely takes balls to do something like this, but it doesn't take "precision control" as the article implies. The skill level on this incredibly low. Basically, all you do is floor the car and steer it between those big ass guides. From the point of view of the driver, you don't even see the loop, you just see road passing in front of you, as normal, except you're "driving up a hill". As long as you don't think about what you're doing, it's cake.
Of course, that's the rub. If you think about what you're doing and the weird forces acting on your body, you could screw up. In summary:
Skill level: 1
Balls level: 8
[Balls level 9 and 10 are reserved for Evel Kneivel] - willhirsch, on 05/18/2009, -0/+0Ah, yes that's different. I guess this could help although I expect they're mostly effective for sustained G-forces rather than sudden ones. Given that he consulted pretty much the leading expert in every area related to the stunt, I'm pretty sure they knew what they were doing in the end.
- willhirsch, on 05/18/2009, -0/+0You're ignoring the fact that rollercoasters can't apply driving force while they're on the loop and aren't allowed to fall off at the top. I suspect the details of the design which was overseen by the senior lecturer in mechanics at the University of Cambridge might make your armchair analysis seem a little amateur in itself.
- willhirsch, on 05/18/2009, -0/+0Amazing... and walking across a tightrope over Niagra Falls isn't supposed to kill you but it's still death-defying.
Defying != contravening. Gravity makes this stunt really difficult to achieve, and the stuntman defied this. - willhirsch, on 05/18/2009, -1/+0Not a single roller coaster loop exists that doesn't hold you onto the track at the top. If you took the restraints of the top sides of the wheels the train would fall off the track.
- willhirsch, on 05/18/2009, -1/+0It's a deduction based on observation. Every loop I've ridden I feel some form of weightlessness - that is, I lift a little off my seat or even am thrust onto the top of the shoulder restraints.
Note that the difference in G-forces isn't that much. The really intense coasters make it up to 6.0. The point is that it's the same effects that make you feel exhilarated at those levels are the same ones that make your body do weird things at slightly higher levels. Rollercoasters are very precisely designed to get as close to the limit as is acceptable without crossing it.
And you have the evidence that he didn't wear a flight suit. Maybe if he did he could have been a bit more liberal on the gas.
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