TopGear Korea sends an automatic chevy spark through a loop the loop....| Grassroots Motorsports forum |

accordionfolder Reader
12/9/12 2:48 p.m.

Video is about half way down the page.

http://www.topgear.com/uk/car-news/video-tg-korea-loop-the-loop-2012-12-06

The way his head gets hit on entering the loop is pretty knarly.....

N Sperlo UltimaDork
12/9/12 3:01 p.m.

G4 (I think) had a sonic jump a giant skate board. Seems likey they want it to be the next big Gymkhana car.

Toyman01 PowerDork
12/9/12 3:07 p.m.

That's just physics, I'd do it...as long as I trusted the guy doing the math.

Tyler H SuperDork
12/9/12 3:10 p.m.

Toyman01 wrote: That's just physics, I'd do it...as long as I trusted the guy doing the math.

The physics of his neck getting popped on the entrance just hurts to watch.

N Sperlo UltimaDork
12/9/12 3:11 p.m.

Unfortunately the Sonic is too top heavy to do anything that hadn't been calculated by 20 NASA engineers.

accordionfolder Reader
12/9/12 3:24 p.m.

N Sperlo wrote: G4 (I think) had a sonic jump a giant skateboard. Seems likey they want it to be the next big Gymkhana car.

https://www.youtube.com/watch?v=C1GBKDl3Anc&feature=youtube_gdata_player

Same event maybe?? Hurts to watch all the same. I think he got out with a broken ankle IIRC.

edit

Found the video in question. Seems a bit harder since he had to point the car in the right direction after landing...

https://www.youtube.com/watch?v=axRU_Hu2BBo&feature=youtube_gdata_player

JoeyM UltimaDork
12/9/12 3:34 p.m.

This was also done by 5th gear back in 2009
http://www.youtube.com/watch?v=wiZoVAZGgsw

mad_machine MegaDork
12/9/12 4:54 p.m.

physics would put at least 1g.. but probably over 2gs on compression on him in order to counteract the pull of earth's gravity

erohslc HalfDork
12/9/12 5:23 p.m.

Well, G's = V^^2/R, where V = velocity, R = radius of the curve.

Based on the parking space lines behind the loop-de-loop, assume that the loop is 80 ft diameter, makes R = 40 ft.

Assume that the G's are > 1, else the car would fall down at the top, so let's say 2.0 G.

Then V = sqrt(2GR), sqrt(23240) = 50.59 ft/sec, or about 35 MPH

But the 'Jerk', change in acceleration vs time would be high with that setup, ie no ramping to give a more gradual change in G.

Carter

Woody MegaDork
12/9/12 5:24 p.m.

Holy crap! There's a Top Gear Korea?!

erohslc HalfDork
12/9/12 5:27 p.m.

I just noticed that in my posting, the formulas values were evaluated to give numeric results:

I had entered "V = sqrt(2 * 32 * 40)", but it showed up as "V = sqrt(23240)"

Teh E36 M3 Dork
12/9/12 5:29 p.m.

We had to pull 3.5 g's to do a loop in a plane. At least the first 90 degrees. All I know is, E36 M3 got damn light around the 2/3-3/4 way point in the plane.

The big head snap had to be the suspension bottoming, right? Couldn't that have been a problem with front wheel traction, and therefore speed at the critical 1/2way point?

Kenny_McCormic HalfDork
12/9/12 5:33 p.m.

erohslc wrote: Well, G's = V^^2/R, where V = velocity, R = radius of the curve. Based on the parking space lines behind the loop-de-loop, assume that the loop is 80 ft diameter, makes R = 40 ft. Assume that the G's are > 1, else the car would fall down at the top, so let's say 2.0 G. Then V = sqrt(2*G*R), sqrt(2*32*40) = 50.59 ft/sec, or about 35 MPH But the 'Jerk', change in acceleration vs time would be high with that setup, ie no ramping to give a more gradual change in G. Carter

35mph is the speed needed to traverse the loop successfully while pulling 1 g of downforce. However I'm going to assume a slushbox Chevy Spark will not maintain speed driving straight up. To get min entry speed we need to find how much the car would decelerate due to gravity going up the first half of the loop, and compensate appropriately.

GVX19 Reader
12/9/12 5:58 p.m.

Holy crap! There's a Top Gear Korea?!

+2 !

Knurled SuperDork
12/9/12 6:05 p.m.

Kenny_McCormic wrote: 35mph is the speed needed to traverse the loop successfully while pulling 1 g of downforce. However I'm going to assume a slushbox Chevy Spark will not maintain speed driving straight up. To get min entry speed we need to find how much the car would decelerate due to gravity going up the first half of the loop, and compensate appropriately.

Which is why roller-coaster loops are not round!

Unlike, apparently, this mobile loop.

Javelin MegaDork
12/9/12 6:48 p.m.

Woody wrote: Holy crap! There's a Top Gear Korea?!

Anti-stance SuperDork
12/9/12 7:24 p.m.

It's even cooler in 'Merica with TWO cars painted up like Hotwheels.

And there was a jump at the end...

Makes the Koreans look like Bob Costas.

https://www.youtube.com/watch?v=3Xc_eh-OlvU

accordionfolder Reader
12/9/12 8:08 p.m.

Anti-stance wrote: It's even cooler in 'Merica with TWO cars painted up like Hotwheels. And there was a jump at the end... Makes the Koreans look like Bob Costas. https://www.youtube.com/watch?v=3Xc_eh-OlvU

Holy poop, I hadn't seen that one before! It really did makeathat one seem puny, didn't it?