flipping a car

[poker192]

How easy it to flip an average car? Notice a car and not a large suv or truck....

When you do flip a car is it it mainly due to striking an obstruction or hitting a ditch and then rolling? or could you also flip b/c you took a turn or corner too fast? (as opposed to mearly spinning out)

does anyone have good advice for discovering the traction limits of your car w/o endagering yourself or others?


thanks

-poker

[SmaartAasSaabr]

Flipping a typical car is fairly difficult since the tires tend to slide. If you have too much grip it could happen. Basically put - you have to do something really stupid to flip a car :lol:

A nice empty parking lot is typically a good place, but in these days of 24/7 operating hours when is it empty...

[TSi+WRX]

Good question - and honestly, it's beyond my rather shallow knowledge base.... :oops:

I'll go ahead and ask this of some of my local road (i.e. an actual track), rally, and autocross racers, they're, in my mind, the most likely to have either encountered such incidences or have enough of a knowledge-base regarding actual vehicle and suspension dynamics to be able to make applicable, real-world comments.

In the mean time, I'd speculate that without *mechanical* failure of some kind (i.e. catastrophic suspension component failure, catastrophic tire/wheel failure while cutting a very sharp corner, etc.), that it would be very hard to do this on the average road-going car, using average road-tires. From my very, very lay point of view, it would stand to reason that the tires' adhesion limits would be reached first, and a slide (be it a wide overdrive or an underdrive push) would be the typical result.

I'll be back!

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Edit - looks like Saabr's a faster typer. :)

Oh, and as for exploring your (and your vehicle's) limits, I also recommend an empty parking lot (one with either no or far-spaced light-posts), but be sure you scope it out first not only for enforcement (this kind of stuff can carry with it quite the penalty), but also that the surface is relatively smooth and free of not only potholes, but also other road-hazards (i.e. nails, trash, etc.).

Additionally, be sure you scope-out the area for potential "play" traffic from neighborhood kids, as it would be a very unfortunate thing to have a kid run onto your test-track unknowingly, while you're spinning-out and out-of-control!

If you would like a more governed menu, autocrossing would be the way to go.

[poker192]

thanks for the responses,

the reason i ask is b/c every day when i get near home i travel down a curvy hill and when i reach a certain speed, i can hear a slight tire squeel and if i go a bit faster a slight slide..... i've heard that cars can corner at higher speeds than one usually expects and i've always wanted to see the upper limits (with preferably only the danger of spinning out) and really knowing what the car will and more importantly not do, in case aliens or a murderer is following me

what you said about the tires reaching a certain point and then just sliding is a familiar concept to me.. I'll often race sailboats, (i'll skip the racing theory of keeping the boat flat for the fastest speed), but as you get closer to the wind the boat begins to "heel" or lean way over to one side.... the larger cruisers have a good size keel, usually in the form of 1500 lbs or more of lead strapped to the bottom....

Heres where the tire theory comes into play, the closer you heel the more of the keel is exposed and the closer you come to putting the boat upside down in the water,

but the second that keels loses contact the boat will turn all the way around and into the wind comnig to a dead stop w/o flipping (at least in theory it should), so I like the idea of the tires sliding after a certain point and it sounds reasonable.....

I've got a long weekened coming up and I'll go parking lot hunting and let you know how it goes.....

[SmaartAasSaabr]

Yeah if say the wheel assembly strikes a curb...

tell ya what if I get my old Crown Vic fired up again I'll go see how easy it is to flip it :D

Mind you considering it's structural integrity maybe not. I got to find a crappy Saab :P

Back in the 1960's, Eric "on the roof" Carlsson (Saab's rally driver) actually flipped his Saabs over on many occasions. He actually used to use the rolling over technique strategically to win :lol: The old 96 had a really strong roof structure so the car didn't really get damaged save for a couple dents of course. Lots of great stories there...
http://www.saabo.com/pictures/data/514/11f.jpghttp://www.saabo.com/pictures/data/514/12f.jpg
edit

Auto-X is a GREAT idea if you want to learn your car's capabilities. I strongly do not recommend trying to find your cars limits on the road. Though you can go closer once you know where they are :wink:

Tires vary greatly... a typical Avalon from the late '90s would just understeer and squeel it's way into the trees if you tried anything hard... in that way it's a fairly predictable car. As you near the edge the car just pushes further and further straight, you back off, the car returns to normal. No real crazy spinout tendencies like say an old 911.

[RadarRick]

Depends on the vehicle. I understand WRX's can be flipped over on the tarmac because of the copious amounts of grip they have, apparently :shock:
I guess it's pretty tough on the street but the dirt would prove not that hard :roll:
RR

[TSi+WRX]

Depends on the vehicle. I understand WRX's can be flipped over on the tarmac because of the copious amounts of grip they have, apparently :shock:
I guess it's pretty tough on the street but the dirt would prove not that hard :roll:


^ I think that the above scenario, when it comes to Subaru Impreza WRXs of the current and immediate-previous chassis generations, would be limited purely to true "race" events.

The road-going versions really have way too much compliance in their suspension for this to happen, unless, of course, there's catastrophic mechanical failure or a true "accident" occurs (i.e. hiking a curb "just-right," impact, etc.). For racing vehicles with more finely calibrated suspensions, exceeding the performance envelope often comes with devastating circumstances, as they may not be as forgiving.

Additionally, the OEM-equipped all-season tires on road-going WRXs - my wife's WRX is fitted with the Bridgestone RE-92, in 205/55/16 fitment - simply do not offer enough grip to induce such behavior. Terminal understeer is typically seen, due to the AWD, but both oversteer and snap-oversteer are possible - both purposefully induced and/or caused by bad driving input.

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Yeah if say the wheel assembly strikes a curb...

^ Agreed - this is one of the "mechanical failure" or "accident-induced" instances that I was referencing - i.e. the tire collapsing off the rim, or, as you illustrated, the wheel curbs.



Tires vary greatly... a typical Avalon from the late '90s would just understeer and squeel it's way into the trees if you tried anything hard... in that way it's a fairly predictable car. As you near the edge the car just pushes further and further straight, you back off, the car returns to normal.

^ That would be what I think, too, although without having driven the car, it would be difficult to tell for certain. There could be hidden issues that this vehicle's suspension may suffer from at-limit that could totally transform this "typical front-driver" into something unpredictable, but I think that without direct experience, based simply on knowledge of "family sedans" of FWD setup, this is a reasonable assumption nonetheless. :)

[DogGod]

You get caught whipping your car around in a parking lot youll most likly get an exhibtion driving ticket. A buddy of mine got one a while back and I cant remember exactly what the penalities were but they seemed a little too harsh for an empty parking lot and some snow.

[TSi+WRX]

^ +1 to all of those, including your sentiments.

Our local enthusiasts typically organize "snow fun" events in out-of-the-way PRIVATE lots. This greatly cuts down on the chances of getting cited.

[TSi+WRX]

Updating -

With just over a half-dozen replies so far (I just posed this question this very morning to my local enthusiast group), the autocrossers, rally-racers, and suspension gurus there all agree....

On an unmodified street vehicle - a typical family sedan - there's so much built-in "safety" in terms of tire selection, suspension design, etc., that it would be near-impossible to induce a true "roll-over" scenario unless some kind of catastrophic mechanical failure were to take place (including a blown tire "digging in"), or unless there's been an "accident" scenario (impact, catching the tire/rim on a curb, when you're already in a horizontal slide).

On a relatively smooth surface, even with aggressive/emergency cornering, this should not be problematic.

[ELVATO]

Hmmm....now if I were to try it with my car... :twisted: LOL, I'd prolly flip :P Though my tires are starting to get a little squeely :P

Is it just me, or there are some types of asphalt that grip alot better than others. It seems that our parking lot(just got repaved) gets really slippery when wet. I have to be a little easy on the gas, or else I just spin :?

[TSi+WRX]

Hmmm....now if I were to try it with my car... :twisted: LOL, I'd prolly flip :P Though my tires are starting to get a little squeely :P

Our local suspension guru and autocross champion (nationally ranked - and if I remember correctly, not too far down from the top, either!) did cite the specific example of "the Ford Explorer + Bridgestone/Firestone debacle" from back in the day.

Apparently, even when consumer advocacy groups tried the experiment, they couldn't get the vehicle to flip, and it was later revealed that the original source which made the "easy flip-over" claim actually resorted to modifying the vehicles to INDUCE such a roll event.

In his (our local guru) opinion, yes, roll-overs are more likely in a vehicle with a higher center of gravity/roll - particularly if there's external factors involved - but that it's still rather hard to do, and that normal driving, including "emergency handling," should not cause this behavior.



Is it just me, or there are some types of asphalt that grip alot better than others. It seems that our parking lot(just got repaved) gets really slippery when wet. I have to be a little easy on the gas, or else I just spin :?

^ I'm not certain about this, as I'm no traffic engineer. :) But yes, it does seem that way to me, too.

[poker192]

TSi+WRX, thanks for the update..... that sounds reassuring...

Yesterday, I went out with a few other friends and another car (which happened to be the exact same car as mine just one year younger) and we found a parkign lot at a soccer complex that is used for a boat launch for some near by water and parking at soccer events, being winter no one wass there..... It's also aways from a main street or any businesses or houses (by mabe a good 3/4 a mile to a mile)

The set up was a long rectangulr area with gentle curbs followed by grass and smooth pavement. Also what I found neat was that it came complete with two grassy islands in the center which were perfect to park a vehicle and minimize any chance of accidently hitting that car.

I first tried a 180 degree turn from reverse, since i figured all it required was a sharp wheel turn and a bit of gas. After I got over the intial shock of feeling a wheight shift in my car, I realized it felt quite stable and my favorite predictable. I practiced it a bit more until I could get into a controlled small area ata bout speeds of 15-20 mph.

My next try were handbrake turns/90 degree turns. These were a bit harder, given i have a pedal to operate my e brake, but with a bit of practice I was able to start to hit those pretty well.

The whole time the car felt very stable and I concluded that unless I was powerslding at very high speeds and the wheight was to suddently shift to one side of the car (as in both tires flatten or car strikes a curb) the car would probably not flip.

After we got sick of shredding the sidewalls of the tires (even tho it was a little wet on the pavement) we just sat on the hood of a car, I noticed what appeared to be a security guard or some other personell drive towards us in an explorer. So we left rather quickly trying to make it so he would not be able to see our license plates.

After we went seperate ways onto the main street so he couldnt get us both, I picked up a blip of k band. Then i went down into a valley and it dissapeared and then as i drove on it kept picking up until I it went full blast.. It was a speed sign... I'd say if the limit was 55 we were travelling a bit above it and it took us at least two minutes until we reached it so maybe a good two miles for the initial blip and a mile of a constant alarm (the area was very hilly but straight roads)

I also did a lot more driving later in the day with giving friends rides and donig fun stuff and I looked at my odometer 155 miles in one day. and I burned a lot of gas.

thanks for the responses!


-poker

[SmaartAasSaabr]

Hmmm....now if I were to try it with my car... :twisted: LOL, I'd prolly flip :P Though my tires are starting to get a little squeely :P

Our local suspension guru and autocross champion (nationally ranked - and if I remember correctly, not too far down from the top, either!) did cite the specific example of "the Ford Explorer + Bridgestone/Firestone debacle" from back in the day.

Apparently, even when consumer advocacy groups tried the experiment, they couldn't get the vehicle to flip, and it was later revealed that the original source which made the "easy flip-over" claim actually resorted to modifying the vehicles to INDUCE such a roll event.

In his (our local guru) opinion, yes, roll-overs are more likely in a vehicle with a higher center of gravity/roll - particularly if there's external factors involved - but that it's still rather hard to do, and that normal driving, including "emergency handling," should not cause this behavior.



Is it just me, or there are some types of asphalt that grip alot better than others. It seems that our parking lot(just got repaved) gets really slippery when wet. I have to be a little easy on the gas, or else I just spin :?

^ I'm not certain about this, as I'm no traffic engineer. :) But yes, it does seem that way to me, too.

There was a Car and Driver article on that at the height of the scandal. They bought an Exploder with Firestones (the good old Wilderness ATX) and fitted a device to the wheel that most likely failed (using the statistics of Exploder crashes) that would deflate it very rapidly on demand. They put the car on a track and tried to flip it. Even with the driver swinging the wheels side to side the truck remained on the road... only if he did something REALLY dumb like rapidly jerk the wheel to the side and slam on the brakes or something like that...

CG is very important in terms of flipping. Basically, the ONLY way for you to flip a car, is for you to get the centre of gravity to lie somewhere outside of the vehicle's track. Ie if the CG is left of the left wheels, or right of the right, the car flips. Otherwise the car does not flip. Of course if the road is banked then the angles change with velocity since the acceleration of the car is pushing against but I digress :P As the CG is made higher, it becomes easier to put the CG outside of the track, if the track isn't widened enough to compensate (heh, a 3 lane SUV).

Different surfaces do act differently. For example concrete doesn't grip as well as asphalt, and if you had really smooth (ie not as porous) asphalt with poor drainage it would be slippery when wet.

[TSi+WRX]

Different surfaces do act differently. For example concrete doesn't grip as well as asphalt, and if you had really smooth (ie not as porous) asphalt with poor drainage it would be slippery when wet.

^ Ah, my Saab-loving friend, that was going to be my initial response, too....but I think that our friend ELVATO had honed-in on the way that different patches of what looks to be the same type of "asphalt" can also feel different, traction-wise.

:)

While I certainly do agree with you on what you posted above, I also can definitely feel differences in what should have otherwise been two similar patches of asphalt or concrete - and what I don't know is if either their surface preparation, or even the "type" of roadway material itself (i.e. one specific "type" of concrete vs. another), if there's any such thing - is what's causing this difference in feel.....

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poker192 - Good to hear that you guys were able to experiment safely! :)