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Old 14th July 2013, 18:26   #91
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Default re: Evasive manoeuvres & Rollovers?

The position of the vehical at the entry and exit point also makes a great impact on how it'll behave on corners. If you can enter and exit at right position in the curve, you will surely feel more 'planted'. Although all SUVs will never be as pliant as their sedan counterparts as far as the cornering goes, there are instances where an SUV may be able to beat the sedan in terms of confidence while cornering provided the right approach is used. An overconfident sedan driver entering into a corner too soon or too late will have his bodyrolls numbered for sure.
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Old 14th July 2013, 18:44   #92
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Originally Posted by tsk1979 View Post
On the safari, I use a simple rule. If the tires start squealing, I am taking the curves too fast.
That said, you can push a monoque much more than you can push a tall ladder on frame.

Moreover, when driving on mountain roads, passengers start getting uncomfortable far earlier than you hit the limits of the vehicle. So as long as you are not ignoring the motion sick passenger, you are doing fine.
Why go till the limit, its not a rally. Staying well within the safety margin is always good.
Such a good post. Thank you.
My Dad told me this when I was a novice driver.
The measure of a good driver is how comfortable and secure his or her passengers feel when he/ she is at the wheel.
As you rightly said, we are lay people and auto enthusiasts, not professional rallyists so why this great hurry. What is there to prove after all?
Safety and comfort first always. The journey is as important as the destination is!
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Old 14th July 2013, 19:46   #93
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by tsk1979 View Post
..........Moreover, when driving on mountain roads, passengers start getting uncomfortable far earlier than you hit the limits of the vehicle. So as long as you are not ignoring the motion sick passenger, you are doing fine.
Why go till the limit, its not a rally. Staying well within the safety margin is always good.
Quote:
Originally Posted by shankar.balan View Post
Such a good post. .......
The measure of a good driver is how comfortable and secure his or her passengers feel when he/ she is at the wheel.
As you rightly said, we are lay people and auto enthusiasts, not professional rallyists so why this great hurry. What is there to prove after all?
Safety and comfort first always. The journey is as important as the destination is!
You are absolutely right, tsk1979. Finally it all boils down to how comfortable your co-passengers are with your driving. There is no point trying to show off at their expense. I agree with shankar.balan; safety & comfort first.

Ultimately, we all get into our cars to reach a 'destination', that target should be paramount, the DESTINATION. Not the speed at which we get there.

Thank you all for the inputs. If it makes even one reader of this thread a better driver, I'd have achieved my 'destination'
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Old 14th July 2013, 20:29   #94
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Originally Posted by SS-Traveller View Post
Samurai has already stated very clearly with reasons, that...

...and neither will the auto OEMs or ARAI / government agencies test this parameter.
You have misquoted Samurai san out of context. He was talking about skidpad testing. Ironic, because unlike the Elk test, where driver response is just as if not more important than vehicle dynamics, skidpad testing is independent of driver response and is a true indicator of vehicle capability. And yes, it is easily doable.

Back to driving tips.

Knowing if the vehicle you are driving is FWD or RWD is also very important. Torque steer can be both useful and/or detrimental to your handling. Try to keep a steady throttle as lifting off will unsettle the suspension. Might be hard to do in a panic situation, but practice and mental preparedness are key.

Cheers.
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Old 14th July 2013, 21:53   #95
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by woodcrawler View Post
Hi Sutripta, Got
this on YouTube
It is not driving on ice but close to it.
If one has some idea of how cars behave, and why, these results are not surprising. The program producers also know that, but laymen do not. So the producers choose these unlikely comparos, essentially for viewership/ shock value/ memorable footage.

Actually, my intention was to focus on
Quote:
Originally Posted by Sutripta View Post
When will one skid? Or topple?
Quote:
FINALLY,
? ..... In Slow; Out Fast
Out fast -> you carry the extra speed down the straight till your next corner. Track day 101.

Regards
Sutripta

Last edited by Sutripta : 14th July 2013 at 21:55.
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Old 14th July 2013, 23:35   #96
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Default re: Evasive manoeuvres & Rollovers?

My Take: Having read all the posts.

1) This is not something that we can calculate from a practical perspective. And I feel we should not bother with the equations for the same either. The number of parameters that will make a significant difference are too many and in my view cannot be calculated by the human mind on the move.

2) Have driven the Safari for 10+ Year and the Aria for 2.5+, currently drive the i10 and the Laura and have booked an EcoSport AT. If the variant one owns has ABS or not and if it has ESP, EBD etc. will make a difference, the number of passengers in the vehicle, the Tyre pressure, the Tyre brand, the Road incline, the Speed, FWD, RWD, AWD, the Steering direction and a lot more factors including CG will make a difference. It is too much.

3) I don't read too much into the reports of the EcoSport toppling, feel it is more to do with driver error than any thing else - If I didn't I would have cancelled the booking but have not. I still may cancel the bookings for other reasons but absolutely not for the toppling.

4) Have had the occasion to have the safari (TCIC) loose the back end in rains during braking (one of the rear drums was jammed) and end up perpendicular to the traffic flow. Have had the occasion of getting out of a absolutely scary emergency braking on a bridge at high speed with the vehicle in front of me stopping too fast with the brake lights not working in the Aria where every thing surely must have worked for me to have got out of it. - Had anything to do with toppling. Surely, I would have been over the bridge and out of this world if the vehicle had not stopped on time and in a straight line.

5) The various posts in these thread are all fine as far as subjective point are concerned, but frankly feel that no equation or knowledge of Physics will help a guy get out of a situation where his/her vehicle may topple due to any number of parameters. What counts at least for me is experience, the feedback a vehicle gives me, the ability to read this feedback and finally common sense. Attempts to compare specific vehicles purely through equations just will not work. Am sure the car designers do study a lot of such parameters to make a vehicle as stable as possible while not considering the external factors but in real life the external factors will impact us too much.

6) The equations will definitely help make the same vehicle more and more stable (for example lowering the centre of gravity of the same vehicle by say taking the spare wheel lower (Safari to Strome) or increasing the wheel base or widening the tracks etc. but the moment one uses the same equations between two vehicles one is changing too many parameters to be able to continue the calculations.

7) Somehow it seems improbably that I would have been able to make a conscious calculated decision to save my vehicle from having an accident or topple in a split second on the above mentioned two or innumerable other occasions. At best one make an automatic subconscious evasive action basis experience and stay far away from angles and moves that could even remotely cause an accident or rather are low percentage moves.

The above is my take and I guess I may be wrong but only seeing a specific extensive calculation that considers all parameters that I have mentioned and many more between two different vehicles to come to a conclusion and some subjective justification would move me from the comment that experience and common sense matters the most, and that one cannot really calculate the parameters and the relation between them well enough to compare vehicles.

Last edited by ACM : 14th July 2013 at 23:46.
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Old 14th July 2013, 23:54   #97
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by ACM View Post
The above is my take and I guess I may be wrong but only seeing a specific extensive calculation that considers all parameters that I have mentioned and many more between two different vehicles to come to a conclusion and some subjective justification would move me from the comment that experience and common sense matters the most, and that one cannot really calculate the parameters and the relation between them well enough to compare vehicles.
Completely. The gist is, you know your ride and it will serve you well. Without knowing the self limitations, there is no point in expecting a technical assistance in getting you through. Well quoted ACM.
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Old 15th July 2013, 08:43   #98
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Default re: Evasive manoeuvres & Rollovers?

Quote:
Originally Posted by ACM View Post
The above is my take and I guess I may be wrong but only seeing a specific extensive calculation that considers all parameters that I have mentioned and many more between two different vehicles to come to a conclusion and some subjective justification would move me from the comment that experience and common sense matters the most, and that one cannot really calculate the parameters and the relation between them well enough to compare vehicles.
Hi.

The OP might have started of with the hope of an easy ready reckoner type calculation of safe speeds, but since then the focus has changed, and even though some technical papers and equations have been posted, doubt any calculations have taken place yet.

I doubt if the OP or any reader will or can find an easy answer to this question. But isn't discussion of ideas what forums are for? Is it realistic to expect a straight forward solution to such a complex question?

One of the biggest culprits of road accidents is lackadaisical attitude towards driving. This is not a measurable statistic, but an untold truth. A refresher sometimes, even in the basic form, even if it leads to pointless debates, works as a subconscious awakener.

So, even though we might not find exactly what we are looking for, or if our calculations are not MIT/IIT grade, why stop? Someone somewhere might wake up and be a better driver.

Cheers.
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Old 15th July 2013, 10:37   #99
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Default re: Evasive manoeuvres & Rollovers?

Quote:
Originally Posted by ACM View Post
My Take: Having read all the posts.

1) This is not something that we can calculate from a practical perspective. ........
The above is my take and I guess I may be wrong but only seeing a specific extensive calculation that considers all parameters that I have mentioned and many more between two different vehicles to come to a conclusion and some subjective justification would move me from the comment that experience and common sense matters the most, and that one cannot really calculate the parameters and the relation between them well enough to compare vehicles.
Quote:
Originally Posted by yogibear007 View Post
Completely. The gist is, you know your ride and it will serve you well. Without knowing the self limitations, there is no point in expecting a technical assistance in getting you through. Well quoted ACM.
Quote:
Originally Posted by gthang View Post
Hi.



I doubt if the OP or any reader will or can find an easy answer to this question. But isn't discussion of ideas what forums are for? I....

One of the biggest culprits of road accidents is lackadaisical attitude towards driving. This is not a measurable statistic, but an untold truth. A refresher sometimes, even in the basic form, even if it leads to pointless debates, works as a subconscious awakener.

So, even though we might not find exactly what we are looking for, or if our calculations are not MIT/IIT grade, why stop? Someone somewhere might wake up and be a better driver.

Cheers.
ACM has put the issue in perspective nicely; and as yogibear007 said, no one knows the car better than the driver. It is for us to assess the eccentricities of the wheels we possess and modify our driving accordingly.

Thank you again, gthang. I know very well that physics might not give me an answer in a real life situation. The whole intention, like you have rightly said is subconsciously awaken ourselves to introspect if we drive 'ideally'. If not, just reading a thread like this might prod us into correcting ourselves so we may become better drivers.

As I said earlier, even if one reader has drawn some inspiration from this great discussion to analyze the way they drive and correct themselves, I have achieved my goal.
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Old 15th July 2013, 15:33   #100
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Default re: Evasive manoeuvres & Rollovers?

Quote:
Originally Posted by tsk1979 View Post
So as long as you are not ignoring the motion sick passenger, you are doing fine.
Quote:
Originally Posted by shankar.balan View Post
The measure of a good driver is how comfortable and secure his or her passengers feel when he/ she is at the wheel.
Absolutely. As drivers we need to concern ourselves more with passenger comfort than anything else no matter how good we are, we think we are, or our cars are.

Besides on Indian roads anything can happen. When you share the road with pedestrians, rickshaws, hand carts, Public buses, etc. you have to retain a large margin of safety. Public roads are not race tracks. If they were at least 50% of Indian drivers having valid licences would fail the tests required to drive on them.

So as long as you drive your car/SUV well within the limits of it's/your ability and as long as you are an attentive and defensive driver and your car/SUV is well maintined; yes your SUV/car and you will survive an emergency evasive maneuver.

The rest is just theory and postulation.

Last edited by navin : 15th July 2013 at 15:34.
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Old 15th July 2013, 16:22   #101
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Default re: Evasive manoeuvres & Rollovers?

I don't know about others but I was getting really concerned every time when the Tata Safari was crossing the speeds of 100-110 KMPH while our drive through NH-2. I asked the driver not to exceed 120 KMPH while he was constantly managing 140-150 KMPH. SUVs are definitely not my cup of tea because I like good handlers, but anytime me driving an SUV, I will dare not cross these speeds because of the inherent handling characteristics of the vehicle. That is why I would prefer a hatchback; or better, a sedan for highway travelling. Also, I hate too much body roll that most SUVs bring on the plate. Sitting for long, esp. at the rear seat makes me sick (driving seat not included).

On another note, I feel that anything over 110-120 on Indian highways is mostly riding on luck.

Regards,
Saket

Last edited by saket77 : 15th July 2013 at 16:26.
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Old 16th July 2013, 11:01   #102
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Originally Posted by navin View Post
Absolutely. As drivers we need to concern ourselves more with passenger comfort than anything else no matter how good we are, we think we are, or our cars are.
Yep absolutely, I tend to drive the same vehicles differently basis who is or isn't the passenger riding along. For example in the Laura if love going round bends at high speeds but with people in the rear bench it gets them feeling nauseous so tend to avoid do any such moves with the back seat occupied. A kid or old parents on board acts as an automatic speed limited. The Parents would never have experienced the kind of speeds we do today on expressways in their fiats and ambassadors so why start now to give them a roller coaster experience.

Limits vary with vehicles, vehicle conditions, passenger types on board, outside road conditions, climate, traffic and so many other factors. One must stay far from the physical limits though, if one is not being paid to be a racing driver why be one? One doesn't get anywhere too much faster in any case and any aspirations of boosting our ego need not be too often or with others on board.

That said:

The Central Telegraph Office closed down this past week, with the last telegram, we still seen the tradition round dial phones in old moves and our kids will never see them, the TV with the traditional picture tube and mobile phones with buttons are both possibly in the last 10 years, the large radios are no micro miniature chips in our Car Head-units and phones. Traditional Driving is headed the same way.

We are eventually moving towards a world where the road and the destination location and many other parameters would drive us rather than the driver or the adrenaline. Am referring to vehicles that drive themselves, trials are already on in many test centres (A recent car show also displayed an entire locality being driven around in such a manner successfully with various brand vehicles using technology from BOSCH to automatically driven themselves.) We then just do not control the speed or come anywere close to the limits of the vehicles. In time the focus will shift towards comfort elements within the vehicles and on getting a comfortable driver with the driver element possibly being restricted to the short drive into and out of our parking lots till we get on to the main roads or on rough terrains. Steering fell and high speed dynamics will maybe not matter that much then. (Plays into the route taken by Mercedes ad Volvo rather than BMW). Wonder how we would get to use the classic cars then. Yep we should be able to see this in our lifetimes. It will be boring to drive then, drivers will be able to look at the scenery though. Let us enjoy todays experience responsibly till then.
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Old 16th July 2013, 14:39   #103
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by Diesel_convert View Post
All car / suv owners can try this experiment:

Drive through a winding road with your seat height at the highest position
and drive back with the lowest position.


You will find a remarkable change in your car's cornering ability.



I find the lower the seat,
the better I can feel the grip available to the car.
In my opinion this may be because you are able to feel the roll of the vehicle more at a higher seating position than when at a lower position. The vehicle may be tilting to the same degree more or less. Means - it may not make so large a difference to affect the perceptible roll of the SUV
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Old 16th July 2013, 15:00   #104
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In my opinion this may be because you are able to feel the roll of the vehicle more at a higher seating position than when at a lower position. The vehicle may be tilting to the same degree more or less. Means - it may not make so large a difference to affect the perceptible roll of the SUV
This is true. When you are sitting high, the same degree of tilt results in more movement. This plus the psychological aspect of sitting high makes you less confident to take on the curves. Shift of couple of inches of the drivers weight is not going to affect the overall CG of a car which weighs more than 1000 kilos.

I also want to bring up another point related to high CG and rolling.
If you take 2 cars with identical ride height/CG, but with differently tuned suspension set ups, the car with softer suspension is (obviously)likely to roll more than the one with a stiffer suspension, and this is likely create some scare (with regards to the stability). But in reality, when the tipping point is reached, it is the car with the stiffer suspension which is likely to topple (2 wheels up in the air). Car with the softer suspension, even though it leans dangerously, will still have all 4 wheels grounded for 'longer period' (till the tipping point is reached). Softer suspension allows part of the mass to shift while the stiffer suspension makes it behave like a single unit(relatively).
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Old 16th July 2013, 16:03   #105
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Default re: Evasive manoeuvres & Rollovers?

Quote:
Originally Posted by Guna View Post
... If you take 2 cars with identical ride height/CG, but with differently tuned suspension set ups, the car with softer suspension is (obviously)likely to roll more than the one with a stiffer suspension, and this is likely create some scare (with regards to the stability). But in reality, when the tipping point is reached, it is the car with the stiffer suspension which is likely to topple (2 wheels up in the air). Car with the softer suspension, even though it leans dangerously, will still have all 4 wheels grounded for 'longer period' (till the tipping point is reached). Softer suspension allows part of the mass to shift while the stiffer suspension makes it behave like a single unit(relatively).
Aren't you contradicting yourself here?

Both the suspensions allow the CG to shift, the softer one earlier and the stiffer one later (with respect to the point of time that the bump or swerve triggered mass shift). The 'softer' and 'stiffer' refers to the damping.

If what you say were to be true ("the stiffer suspension makes it behave like a single unit(relatively)"), wouldn't rally cars - with stiff suspensions and virtually 0 body roll under normal circumstances - be spending more time on their sides or roofs instead of wheels? Stiffer suspension allows the wheels to be on the road longer, even if the body rolls. At the tipping point, the suspension would be at the end of travel (compression in the side to which mass shifted, extension in the side that the mass shifted from). At this point the chassis, suspension and body are a single rolling mass.
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