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Just curious. On a country street with a hairpin 90-degree turn on level pavement and factory installed sports suspension and factory 17 inch tires, what is the fastest you can take the corner?
When I went for my 1st test drive with my MA before I ordered I was told not to slow down at all, just punch it in 2nd gear. I thought my MA was crazy. Of course I slowed for every corner as I had never driven like this before. Finally I decided to trust the guy and the car and did a 90 degree corner at about 35. This was in a stock cooper with 15" rims and the 175 wide tires.
When I went for my 1st test drive with my MA before I ordered I was told not to slow down at all, just punch it in 2nd gear. I thought my MA was crazy. Of course I slowed for every corner as I had never driven like this before. Finally I decided to trust the guy and the car and did a 90 degree corner at about 35. This was in a stock cooper with 15" rims and the 175 wide tires.
My MA is Harash of MOp.
When i went for my first test drive, i had him too. At first i thought he was crazy aswell, but after 10min or so i trusted him and really start moving down those peabody back roads.
I didn't have time to draw a graph showing the proper curvature necessary to accomplish a turn that results in the car facing 90 degrees from its previous reference point on the road. Chows4us will now calculate the exact point at which a car heading east at 70 miles-per-hour will intersect with a car driven by Chowsus heading west on the same road traveling at 30 miles-per-hour but has to stop for 94 seconds to calculate the exact distance from the nearest Startrek convention; when the cars start out their journey some 121 kilometers apart. I will expect the answer in 15 minutes.
My answer is "Just below the posted speed limit, Officer".
A 2 lane right is a lot slower than a 4 lane left.
Blazermaniac should have to clean my screen. It is his fault it has tea on it.
__________________ Percy '07 DS/DS Hardtop with a few tricks. Mac '12 HG Softtoploaded. Two Minis are not too many, it's not a question.
Percy corners like a Dixie Chopper!
MMC #576
Let's roll!
I didn't have time to draw a graph showing the proper curvature necessary to accomplish a turn that results in the car facing 90 degrees from its previous reference point on the road. Chows4us will now calculate the exact point at which a car heading east at 70 miles-per-hour will intersect with a car driven by Chowsus heading west on the same road traveling at 30 miles-per-hour but has to stop for 94 seconds to calculate the exact distance from the nearest Startrek convention; when the cars start out their journey some 121 kilometers apart. I will expect the answer in 15 minutes.
No point in getting all huffy about it. Your original question has problems. Without stating the radius of the curve, the question and answers are meaningless. Hairpin turns, by definition, are sharper than 90 degrees, they are closer to 180. So, I could answer your question with any speed and I would be correct.
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Robin Casady Bombadil: 2007 MINI Cooper S, R56, Pure Silver, LSD, Wood Shift Knob, Rota Slipstream 16x7, NAV, HIFI...
No point in getting all huffy about it. Your original question has problems. Without stating the radius of the curve, the question and answers are meaningless. Hairpin turns, by definition, are sharper than 90 degrees, they are closer to 180. So, I could answer your question with any speed and I would be correct.
Yeah! I hate Blazermaniac so much. Down with him and his inaccurate questions! Not only is he inaccurate, but I think fairly stupid. Dumber than a retarded elephant I would guess. By the way, if I push the sport button on my Mini, I notice that the suspension travel is less pronounced. Any truth to this or is it just a function of tighter steering?
90 degrees is not impossible. What you are hanging up on is reference point. The reference point that I used, and that 7 people before you responded devined, was at the beginning of the turn, which would be 90 degrees when referenced to the end of the turn. Think of it as a protractor, the protractor is a curve on the outer edge with and intersecting point in the middle. Now true, the length of the turn also determines how sharp the turn is. What was meant by hairpin, (although technically not the exactly precise term and I would note that you gave this part of the question no notice until another person pointed it out) is a sharp turn such as an intersection. Think of an L intersection in your mind. Now given those parameters, albeit imprecise parameters, I think that somewhere between 30-40 mph could be the answer. Although I would love to see the guy at the track do it at 60 mph. Given the extra room at a track, I think that would be awesome.
You're right - a "90-degree turn" is simply any turn that changes the direction of your car by 90 degrees between when you enter the turn and when you finish the turn. Unfortunately, that's not enough by itself to tell you how fast you can take the curve. As you've said, it's all a matter of how "sharp" the turn is - that is, how small the radius of the curve is.
You could execute a 90-degree direction change at 120MPH without slipping, but the radius of the curve would probably have to be several thousand feet.
If you can tell us the radius of the curve at its tightest point, I can tell you how fast you can take the curve. Without a reasonable estimate of the dimensions of the curve, everything in this thread is just "guesstimation", at best.
You're right - a "90-degree turn" is simply any turn that changes the direction of your car by 90 degrees between when you enter the turn and when you finish the turn. Unfortunately, that's not enough by itself to tell you how fast you can take the curve. As you've said, it's all a matter of how "sharp" the turn is - that is, how small the radius of the curve is.
You could execute a 90-degree direction change at 120MPH without slipping, but the radius of the curve would probably have to be several thousand feet.
If you can tell us the radius of the curve at its tightest point, I can tell you how fast you can take the curve. Without a reasonable estimate of the dimensions of the curve, everything in this thread is just "guesstimation", at best.
Right on. Now we are getting somewhere. I'm guessing that on a country road with an L intersection, it would be somewhere around 45-60 feet.
The turn radius is probably bigger than 45-60 feet. After all, the minimum turn radius for the MINI is 17 feet, 6 inches, and that's with the steering wheel turned all the way to full lock. Presumably, you're not having to turn the wheel anywhere near that far to negotiate the curve you're talking about.
If the radius of the turn were actually only 60 ft, you'd be limited to about 28MPH, assuming a maximum lateral acceleration of .91g
EDIT - If you'd like to find maximum cornering speeds for different curve radii, the formula is:
Multiply the radius of the curve (in feet) by the maximum lateral acceleration of the car, take the square root of the result, and multiply by 3.869. That will give you the cornering speed in MPH.
The 3.869 is just a constant that includes gravitational acceleration in feet per second squared, as well as the constants to convert from feet-per-second to miles-per-hour.
So, for a 60-ft radius curve, and a maximum lateral acceleration of .91g, that gives SQRT(60 * .91) * 3.869, or 28.6 MPH.
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Last edited by ScottRiqui; 08-11-2007 at 07:57 PM.
I added the math to my previous post. The .91g just came from the first magazine test of the Cooper 'S' I found. It should be in the ballpark, although I've seen other scores for the MINI in the .87-.91g range.
Note that the equation I gave won't work as well if you're not going through at least 90 degrees or so of direction change, because the maximum lateral acceleration number goes up if you're only having to make small direction changes.
I've actually gotten lateral acceleration numbers in excess of 1g on my MINI, but that was for quick left-right-left transitions with only 20-30 degrees of direction change each (like a slalom)
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Last edited by ScottRiqui; 08-11-2007 at 08:10 PM.
The turn radius is probably bigger than 45-60 feet. After all, the minimum turn radius for the MINI is 17 feet, 6 inches, and that's with the steering wheel turned all the way to full lock. Presumably, you're not having to turn the wheel anywhere near that far to negotiate the curve you're talking about.
If the radius of the turn were actually only 60 ft, you'd be limited to about 28MPH, assuming a maximum lateral acceleration of .91g
EDIT - If you'd like to find maximum cornering speeds for different curve radii, the formula is:
Multiply the radius of the curve (in feet) by the maximum lateral acceleration of the car, take the square root of the result, and multiply by 3.869. That will give you the cornering speed in MPH.
The 3.869 is just a constant that includes gravitational acceleration in feet per second squared, as well as the constants to convert from feet-per-second to miles-per-hour.
So, for a 60-ft radius curve, and a maximum lateral acceleration of .91g, that gives SQRT(60 * .91) * 3.869, or 28.6 MPH.
That is cool, thanks. As an English major, I love stuff like that, but could never think it up myself.
Now, if I can just convince the state highway department that posting turn radii would be public service, I could use that information to optimize my daily commute.
Country street- then speeds are limited by speed limit posted.
In my area all residential roads are limited to 25 mph.
A legal turn at 90 degrees on a two lane road can be done a tad faster than the posted speed limit. If done cleanly one would probably get into no trouble with the law. So the estimate of 28.6 mph is very close to my experience which is about 26+ mph.
I approach the turn and let the car slow to 25 then as smoothly as possible steer through the turn with slightly keeping on the throttle until the apex of the turn then apply a bit more throttle before any speed is lost. The turn itself is above 25. There is no sound from the tires and the car stays pretty flat.
With a larger radius turn you can turn much faster 30+ mph easily. In a sweeper turn with several hundred feet turn radius on a track usually we can do about 60 in third gear entering and about 85 exiting with no problems.
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#43 Street Modified (SM) Class SCCA Hawaii Region
2005-2009 Solo Run Off and Points Champion (Hawaii)(2nd 2006 Points)
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PEPPER WHITE PEERAGE # 762
Your always turning in an arc.
Percy '07 DS/DS Hardtop with a few tricks. Mac '12 HG Softtop loaded. Two Minis are not too many, it's not a question.
As an English major, I love stuff like that, but could never think it up myself.
