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View Full Version : NASCAR cars don't drift?


mangeorge
03-08-2009, 03:00 PM
And so mangeorge ponders.

Hero From Sector 7G
03-08-2009, 04:32 PM
I've heard the downward push from aerodynamics is so great they could drive on the underside of a surface. If that is true (I am skeptical) than I could see why they don't drift.

Diz
03-08-2009, 05:51 PM
I've heard the downward push from aerodynamics is so great they could drive on the underside of a surface. If that is true (I am skeptical) than I could see why they don't drift.

That isn't true of Nascar type cars. The big wings on open wheel cars like F1 and Indycar create more pounds of downforce than the weight of the car. That doesn't mean they could drive upside down in reality. They might, but there would be a multitude of problems to overcome.

Nascar cars only drift in the sense that going through a turn at the maximum possible speed involves a small amount of sliding. The "sport" of drifting is something entirely different from the sport of racing.

El_Kabong
03-08-2009, 07:38 PM
Drifting is a state of controllable oversteer ('loose' in NASCAR terminology). According to my possibly faulty understanding of the mechanics of a NASCAR Sprint Cup car, this is something to be avoided, as it makes one slower through the corners, particularly on exit, and results in faster tire wear. Likewise, given that these are rear-wheel drive cars with approx. 800 HP to play with, it is extremely difficult to keep an excessively loose car from spinning out.

The ideal is perfectly neutral handling, with both front and rear tires on the ragged edge of adhesion. In practice, due to variations in suspension geometry, track temperature changes, and balance changes as fuel burns off and tires wear during a run, cars will be either 'tight' (front tires lose grip first) or loose (rears first) at various times and the pit crew usually has to make numerous minor changes during the race to keep the handling as close to neutral as possible. With the current generation of cars, the default setup seems to be somewhat loose anyway. During today's race at Atlanta, most of the cars seemed to lose rear traction momentarily coming out of turn 4, and the drivers were clearly having to work hard to keep their cars more or less straight while accelerating away.

Dog80
03-08-2009, 08:02 PM
Neither do F1 cars drift. Multiple reasons:

1. There's nothing to gain from drifting. Nascar and F1 take place on circuits with large-radius corners, the fastest way around such a corner is by following a proper racing line, not drifting.

2. Too high speeds and tires not designed for drifting means that when the car's tail starts slipping even a little, it can easily go out of control. The heavy reliance on aerodynamics only makes things worse and more unpredictable.

On the other hand you'll see lots and lots of drifting on WRC and rallying in general (http://youtube.com/watch?v=zsmBVN39chQ). The speeds involved there are significantly lower and the stages are usually mountain roads with tight bends and hairpins. The best way to tackle a tight bend is by drifting because at the corner exit the car is facing the right direction and you still have some momentum from before entering the corner so you can go full throttle.

mangeorge
03-08-2009, 08:09 PM
That isn't true of Nascar type cars. The big wings on open wheel cars like F1 and Indycar create more pounds of downforce than the weight of the car. That doesn't mean they could drive upside down in reality. They might, but there would be a multitude of problems to overcome.

Nascar cars only drift in the sense that going through a turn at the maximum possible speed involves a small amount of sliding. The "sport" of drifting is something entirely different from the sport of racing.
Well, slower speed race cars (rally, midget, stockers, etc) do drift. Sports cars too. Drifting in a race is an important skill. I think, as mentioned, the 200 mph cars are too fast.

mangeorge
03-08-2009, 08:25 PM
On the other hand you'll see lots and lots of drifting on WRC and rallying in general (http://youtube.com/watch?v=zsmBVN39chQ). The speeds involved there are significantly lower and the stages are usually mountain roads with tight bends and hairpins. The best way to tackle a tight bend is by drifting because at the corner exit the car is facing the right direction and you still have some momentum from before entering the corner so you can go full throttle.
Yeah, that! If I were to have gotten into racing, it would have been rally. It is fun.
Thanks for the video link.
Oh yeah, go carts too. Not your 5hp (http://youtube.com/watch?v=zWT6xd3qvkg) rigs, though. ;)
Cool hobby if you can afford it. And if you have some hand-eye left. :(

John DiFool
03-08-2009, 11:06 PM
Don't confuse drifting with slip angles (http://auto-ware.com/setup/slp_hndl.htm). Each type of race car has an optimal slip angle at which it will have optimum grip in a turn. But if a NASCAR racer is "drifting" the driver has made a mistake and is attempting to correct it.

Really Not All That Bright
03-08-2009, 11:18 PM
Neither do F1 cars drift. Multiple reasons:

1. There's nothing to gain from drifting. Nascar and F1 take place on circuits with large-radius corners, the fastest way around such a corner is by following a proper racing line, not drifting.
F1 cars certainly do slide- just not enough for you to see it. It does become noticeable on certain bumpy corners, though. The Autodomo Hermanos Rodriguez in Mexico, where the held the Mexican Grand Prix until 1992ish, was the bumpiest, which led to its removal from the F1 calendar.

The Tamburello chicane at Imola (San Marino) was extremely bumpy too. They may have resurfaced it properly by now; the last time I saw a race there was in 1994.

( :( )

mangeorge
03-08-2009, 11:21 PM
Don't confuse drifting with slip angles (http://auto-ware.com/setup/slp_hndl.htm). Each type of race car has an optimal slip angle at which it will have optimum grip in a turn. But if a NASCAR racer is "drifting" the driver has made a mistake and is attempting to correct it.
Drifting is pretty well illustrated in both those linked videos.
From what little NASCAR I've seen on the tube, once the driver loses traction he's gone. Sometimes they lose it while going straight.

Really Not All That Bright
03-08-2009, 11:25 PM
The Autodomo Hermanos Rodriguez in Mexico, where the held the Mexican Grand Prix until 1992ish, was the bumpiest, which led to its removal from the F1 calendar.
Missed the edit window: that's Autodromo, not -domo.

Diz
03-09-2009, 03:43 AM
Well, slower speed race cars (rally, midget, stockers, etc) do drift. Sports cars too. Drifting in a race is an important skill. I think, as mentioned, the 200 mph cars are too fast.

Speed isn't really a factor, though aerodynamics do play a part. Drifting (in the sense of going around a turn at say, a 45 degree angle) is going to be slower at 20mph as well as 200mph. On dirt tracks the cars you mention will drift, but the physics of driving on dirt is quite different from pavement and the cars will be setup very differently. See the mention of slip angle above.

Now as you say, rally cars will sometimes drift on pavement. They have issues to deal with that aren't normally present in closed course racing where outright speed is paramount. They don't have the luxury of taking lap after lap on a mostly unchanging course to get each turn perfect. So they take 95% of what they can get in exchange for not crashing every third turn.

Bottom line, if you see a car drifting on pavement (that is, exceeding the optimum slip angle), they are virtually guaranteed to not be taking the turn as fast as possible :)

Dog80
03-09-2009, 08:04 AM
Now as you say, rally cars will sometimes drift on pavement. They have issues to deal with that aren't normally present in closed course racing where outright speed is paramount. They don't have the luxury of taking lap after lap on a mostly unchanging course to get each turn perfect. So they take 95% of what they can get in exchange for not crashing every third turn.

Bottom line, if you see a car drifting on pavement (that is, exceeding the optimum slip angle), they are virtually guaranteed to not be taking the turn as fast as possible :)

Well, I disagree. Drifting is the fastest way around certain corners. Look the video link I posted earlier. These corners are so tight that if they wanted to take them using racing lines they would have to bring the car to almost a standstill and downshift to first gear. That means lots of lost time plus the engine gets off the power band.

In contrast, taking the corner with drifting means that you can enter the corner in whatever gear you had previously (or downshift a gear) and can use the car's momentum to get you through the corner. This is especially useful when going uphills. Then, at the corner exit your engine is in the optimum power range so you simply gun down the throttle and you're off.

Of course rally drivers do not drift all the time. They take large radius corners using racing lines like in other forms of motorsport because it is more efficient. Also, when they do drift they just use as much drift angle necessary and not more. Do not confuse Japanese style extreme-angle drifting which is mostly for show with rally drift.

mangeorge
03-09-2009, 09:11 AM
Speed isn't really a factor, though aerodynamics do play a part. Drifting (in the sense of going around a turn at say, a 45 degree angle) is going to be slower at 20mph as well as 200mph. On dirt tracks the cars you mention will drift, but the physics of driving on dirt is quite different from pavement and the cars will be setup very differently. See the mention of slip angle above.

Could a car (NASCAR) perform a controlled drift at 200 mph? They're barely making the normal turn at that speed. In fact, they're barely holding traction on the straights at top speed.

E-Sabbath
03-09-2009, 11:40 AM
They _can_ recover from being bumped sideways midpack at 200 MPH. If they're very lucky.

Diz
03-09-2009, 04:06 PM
Well, I disagree. Drifting is the fastest way around certain corners. Look the video link I posted earlier. These corners are so tight that if they wanted to take them using racing lines they would have to bring the car to almost a standstill and downshift to first gear. That means lots of lost time plus the engine gets off the power band.

In contrast, taking the corner with drifting means that you can enter the corner in whatever gear you had previously (or downshift a gear) and can use the car's momentum to get you through the corner. This is especially useful when going uphills. Then, at the corner exit your engine is in the optimum power range so you simply gun down the throttle and you're off.

Well, yes and no. As I said, rally drivers have good reasons for using that driving style. For the types of cars they use and the conditions they race under, drifting as they do is definitely the best way.

But it is absolutely not true that the fastest way around a tight turn is by drifting like that. A sliding tire doesn't produce any more grip than a non-sliding tire (less, actually) and the speed you carry through a turn is a function of how much grip you have. In the type of racing I do (autocross) we have turns even tighter than those in the video and taking a proper racing line is invariably the fastest way. The problem for rally drivers is that taking the optimum racing line requires braking at precisely the right point, turning at precisely the right point, getting back on the throttle at precisely the right point, etc... Get any one of those steps wrong and you're either very likely to go off the road, or at least lose a lot of time. There's just no way for a rally driver to know exactly where each of those points are on a long, dynamic, unfamiliar course. So, perhaps counter-intuitively, sliding as they do actually gives them more control and a bigger margin for error while minimizing the amount of time lost, for the reasons you stated.

Could a car (NASCAR) perform a controlled drift at 200 mph? They're barely making the normal turn at that speed. In fact, they're barely holding traction on the straights at top speed.

That's where my aerodynamics caveat comes in :)
Race cars rely so much on downforce at those speeds that getting even a little sideways will mess up the airflow and take away that added grip, making it almost impossible to recover from a slide. But if you used a car that wasn't designed to produce downforce, you could theoretically drift at 200mph. Of course it would be incredibly dangerous and difficult...

Least Original User Name Ever
03-09-2009, 04:39 PM
Missed the edit window: that's Autodromo, not -domo.


Domo arigato.

Cerowyn
03-09-2009, 05:15 PM
NASCAR cars have only a few hundred pounds of downforce, unlike open-wheel cars like F1. There is a movie clip, perhaps an IMAX special IIRC, that demonstrates an F1 car driving upside down at speed. A NASCAR car would roll over once that angle became too steep.

A NASCAR can't drift well for a variety of reasons, including the suspension set up (which is optimized for left turns, making the opposite steering portion of the drift harder to do) and tires. In fact, most track-racing tires would be dreadful for drifting.

Corners are only faster to take in a drift when the limits of traction are sufficiently low enough to make the sliding transit faster. Even in rallying, in which my godfather had a long and successful career, not every corner was worth drifting through.

[Um, none of this is probably original to the thread. Just adding my voice to agree.]

Really Not All That Bright
03-09-2009, 05:24 PM
NASCAR cars have only a few hundred pounds of downforce, unlike open-wheel cars like F1. There is a movie clip, perhaps an IMAX special IIRC, that demonstrates an F1 car driving upside down at speed. A NASCAR car would roll over once that angle became too steep.
Not in real life. F1 cars can't actually drive on the ceilings- it's theoretical only.

The problem is that the amount of downforce "stolen" by the weight of the car pulling away from the ceiling significantly reduces the amount of traction, and an F1 car will spin its wheels in any gear if downforce is lost. Thus, it can't actually maintain the speed required to maintain the downforce, and it would quickly drop back to the floor.

Look at it this way: the right way up, an F1 car produces (say) 750 lbs. of downforce at 180 mph, plus its own weight- say, another 750 lbs., for a total of 750 lbs. of keep-wheels-on-groundness.

Flipped upside down, it produces the same downforce, but negative weight, meaning there are 0 lbs. of any force acting to keep the wheels on the ground (ceiling).

mangeorge
03-09-2009, 05:49 PM
Maybe this (http://youtube.com/watch?v=oHDojzNA8gs)?
Not real, of course. But cute.

Necros
03-09-2009, 06:57 PM
Well, I disagree. Drifting is the fastest way around certain corners.
Rally cars "drift" around a corner because it sweeps away the loose material of the road, and allows the tires to find better purchase on the underlying, harder, surface, not because the turns are tighter or to position themselves for acceleration. In addition, attempting to grip on a surface made out of gravel, sand, mud, ice and snow is basically impossible. I would be much faster around a course if I could actually grip, but it just ain't happening. The drift is a function of the surface, though, not of the course layout.

John DiFool
03-09-2009, 08:58 PM
That's where my aerodynamics caveat comes in :)
Race cars rely so much on downforce at those speeds that getting even a little sideways will mess up the airflow and take away that added grip, making it almost impossible to recover from a slide. But if you used a car that wasn't designed to produce downforce, you could theoretically drift at 200mph. Of course it would be incredibly dangerous and difficult...

There's been much debate in the Grand Prix Legends community about the realism of its physics model, but you can drift like crazy in that sim as downforce is definitely not a factor.

mangeorge
03-09-2009, 09:13 PM
Rally cars "drift" around a corner because it sweeps away the loose material of the road, and allows the tires to find better purchase on the underlying, harder, surface
:D, just in case you're kidding.
Otherwise, I'd like to see some citie titie for that idea. Please.
Oh, you mean for the cars behind the sweeper pilot!

Really Not All That Bright
03-09-2009, 09:22 PM
He's half right.

Drifting on dirt/gravel surfaces causes loose material to build up against the side of the tyre, which retards sideways motion. Rally cars aren't fitted with ABS for similar reasons; on loose surfaces, you have to lock the wheels to slow down quickly, because it allows dirt/gravel to build up in front of the tire contact patches.

So, drifting sweeps the loose material of the road, but that's in order to "push" against it, not to expose a better surface underneath.

Pork Rind
03-09-2009, 09:28 PM
Look at it this way: the right way up, an F1 car produces (say) 750 lbs. of downforce at 180 mph, plus its own weight- say, another 750 lbs., for a total of 750 lbs. of keep-wheels-on-groundness.


Just for the record, according to Wikipedia (http://en.wikipedia.org/wiki/Formula_One_car) (and this jibes with my memory), F1 cars are already creating twice their weight in downforce at only 118mph. Weight=downforce by about 80mph.

Most recent figures (http://forums.autosport.com/showthread.php?threadid=98037) I could find have the cars generating about 3,300 pounds of downforce in the 2006 season.

Really Not All That Bright
03-09-2009, 11:08 PM
Just for the record, according to Wikipedia (http://en.wikipedia.org/wiki/Formula_One_car) (and this jibes with my memory), F1 cars are already creating twice their weight in downforce at only 118mph. Weight=downforce by about 80mph.

Most recent figures (http://forums.autosport.com/showthread.php?threadid=98037) I could find have the cars generating about 3,300 pounds of downforce in the 2006 season.
The figures I used were just examples. It still renders the "car on ceiling" thing impossible, though. Gordon Murray wrote an article about it in the McLaren technical bulletin back in 1992 or 1993 or so.

Necros
03-09-2009, 11:51 PM
:D, just in case you're kidding.
Otherwise, I'd like to see some citie titie for that idea. Please.
Oh, you mean for the cars behind the sweeper pilot!
No, I am not kidding, and I am all right, despite what RNATB thinks. How about from here: http://team-oneil.com/press1.htm
Sliding the tires sideways across the surface sweeps away the loose gravel and gets the tire down to the better grip below the loose surface.

Necros
03-10-2009, 12:15 AM
BTW, I didn't mean to come off all snarky to RTNATB. Throw a ;) in there somewhere.

Leaper
03-10-2009, 12:58 AM
Only in Tokyo.

Gatopescado
03-10-2009, 01:40 AM
Looks fun, lots of smoke. Not racing. Strictly entertainment.

If the wheel is spinning, the car isn't moving forward at the optimal rate.

That is why F1 and "other" racers don't "drift" (on purpose, at least). They are racing, not putting on a show.

Robot Arm
03-10-2009, 03:35 AM
This could be another of those airplane-on-a-treadmill things.

I'm thinking of it in terms of a coordinate system centered on the car, and pointing in the car's direction of travel (and the car will not always be facing the same direction it's moving). In order to change direction, you need to generate a sideways force. You want that sideways force to be as great as possible, to make the turn in the shortest amount of time.

So whether drifting is benefical comes down to this. Is possible for a car to generate more sideways force by pointing off-line and spinning the drive wheels than by keeping the wheels rolling at their best slip angle?

I'm sure there's more to it. (Can the drifting car also generate enough forward force to maintain the optimum cornering speed?) That's as far as I've gotten so far, though.

mangeorge
03-10-2009, 09:01 AM
Looks fun, lots of smoke. Not racing. Strictly entertainment.

If the wheel is spinning, the car isn't moving forward at the optimal rate.

That is why F1 and "other" racers don't "drift" (on purpose, at least). They are racing, not putting on a show.
This isn't really about show-off drifting, which can be pretty cool by the way.
it's about drifting through a turn in a race, as a technique to get out of the turn faster. Read the rest of the thread and you'll see mentions of racers who do drift, on ourpose.
A long time ago I read a book by an english race car driver (sports cars) about racing and techniques, such as "clipping apexes", "heel and toe" handling of brake and accelerator, drifting and other tricky stuff. It was written, I think, in the "50s, and times have changed, but it was not about show drifting.
I wish I could remember the author.
Besides, drifting, like wrestling, is fun. :p
BTW; how'd you do at Monte Carlo last year?

Goblinboy
03-10-2009, 04:46 PM
Drifting in Nascar from last weeks race in Las Vegas (http://youtube.com/watch?v=-3cwVTpUPHc)

Not intentional, but not something you normally see at 180mph either. Watch the clip the whole way through to see the drifting. The shot from the following car is probably the best.

E-Sabbath
03-10-2009, 07:19 PM
Goblinboy: Exactly, precisely what I was thinking of above.

mangeorge
03-10-2009, 07:44 PM
Drifting in Nascar from last weeks race in Las Vegas (http://youtube.com/watch?v=-3cwVTpUPHc)

Not intentional, but not something you normally see at 180mph either. Watch the clip the whole way through to see the drifting. The shot from the following car is probably the best.
I gotta give it to the driver, he did drift the car. Intentional or not. The beginning was oops, but the recovery was pure skill. It could have been messy.
I don't follow NASCAR, so I know nothing about the driver.

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