Anybody know the Radius of Turn 2 at Thunderhill?

[Gary Smith]

I'd like to play around with calculating lateral g-force and Thill's turn 2 seems like a good place to experiment. Any comments or ridicule appreciated.

 

[67GTA]

“For example, turn 2 at Thunderhill is a long flat 180° turn with a radius of about 325 ft.”

Quoted from the article on the link below. Based on what you’re trying to do, I’m guessing you will enjoy this.

The Science of Driving

 

[Gary Smith]

Wow! Thanks! I'm not actually ready to use the info yet but since you called my bluff I'll get on it. And yes, I will enjoy Professor Korf's article. I recommend his very good book for beginners - You Suck At Racing.

 

[Grant 302]

Any comments or ridicule appreciated.

Lol. We need more people like you...On this planet.

 

[Gary Smith]

The equation G = (V^2)/R is frequently encountered in discussions of the physics of racing. This simple formula can be confusing if you don’t realize that the G does not represent units of g-force but rather circular acceleration. To get units of g-force you must divide the acceleration given by the formula, by earth’s gravitation in appropriate units.

For example, I can sort of maintain 70 mph through Thunderhill’s turn 2
70 mph = 31.3 meters / second, The 325 feet radius of turn 2 is 99 meters
(31.3^2) / 99 = 9.895 meters / sec^2
Divide this result by earth’s gravitation which is 9.81 meters / sec^2 = 9.895 / 9.81 = 1.01 g

This result is obviously a nice starting place. Now I should be able to reach all kinds of goofy conclusions.

 

[67GTA]

The equation G = (V^2)/R is frequently encountered in discussions of the physics of racing. This simple formula can be confusing if you don’t realize that the G does not represent units of g-force but rather circular acceleration. To get units of g-force you must divide the acceleration given by the formula, by earth’s gravitation in appropriate units.

For example, I can sort of maintain 70 mph through Thunderhill’s turn 2
70 mph = 31.3 meters / second, The 325 feet radius of turn 2 is 99 meters
(31.3^2) / 99 = 9.895 meters / sec^2
Divide this result by earth’s gravitation which is 9.81 meters / sec^2 = 9.895 / 9.81 = 1.01 g

This result is obviously a nice starting place. Now I should be able to reach all kinds of goofy conclusions.

Thanks for clarifying the units of measure - I tried a few quick calculations using MPH and Feet, and couldn’t work the formula back to the results in his table. Figured it had to be specific units of measure, but the article didn’t call that out. Very interesting.

edit - just worked the conversion to feet/second, which is 32.185 for the conversion to G-force. Convert MPH to Feet/Second which allows using the radius in Feet.

 

[Norm Peterson]

I'd like to play around with calculating lateral g-force and Thill's turn 2 seems like a good place to experiment. Any comments or ridicule appreciated.

Interesting thought.

You might also want to have estimates for the radii to the actual driving line in two or three places . . . not sure how to come by those numbers, though.


Norm

 

[Grant 302]

Interesting thought.

You might also want to have estimates for the radii to the actual driving line in two or three places . . . not sure how to come by those numbers, though.


Norm

Funny. I was thinking about this yesterday...apparently a few hours before you posted. I’d usually do this on a desktop, but one of my 2020 resolutions was to spend far less time on the desktops.

Anyway, this is what I did on the phone yesterday for a rough estimate. Looks to me like the driving line might be a bit less than the 325’ estimate. But I think I understand your point about the (sometimes) huge difference between the radius of the physical paving vs ‘the line’. Apologies for the crude phone generated pic...



This is like what I’d do on a desktop anytime I was wondering about specific track geometry.