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Old 12th July 2013, 13:32   #61
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by VeyronSuperSprt View Post
Destructive testing is used extensively in IT/Software too. Critical applications are put through destructive testing to establish reliability levels as are software products sold at a global level.
During my stint in the corporate IT world, we did not use that term. We called it stress testing, comes to close to the meaning of destructive testing in hardware. Since software can't be destroyed, I feel destructive is the wrong usage. We also have crash testing, where different machines are just switched off and then see how rest of the hive manage without that machine, and how the machine recovers when switched on. Anyway, end of OT.

SUV can survive the evasive maneuver provided the driver is driving in optimal speed for that vehicle. I drive the Grand Vitara at 80-100kmph at regular highways, and get down to 40-60kmph in ghats. This is a speed at which I can do evasive maneuver without losing control, in the Grand Vitara. This is based on my limits, on which no formula can be applied. Each one has to learn his/her own limits in their SUV by practice.
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Old 12th July 2013, 14:49   #62
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Default re: Evasive manoeuvres & Rollovers?

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Each one has to learn his/her own limits in their SUV by practice.
There are two ways to learn/improve one's driving. One is by using the "seat of the pants" technique, which your suggestions would fall under. The other, is to use your head, and to use the seat of your pants to validate what you should feel.

The drawback with the seat of the pants technique is that you are limited to only what you have already experienced. It will make you a good driver, on the roads you are used to. On the other hand, using your head makes you a better driver, period. It's a personal choice how one wants to learn.

One thing is common across the board, though. No one likes to hear that their driving can be improved. Seems to be an universal sore spot.

It's ridiculous to think that one can actually calculate "g" forces in your head while driving, and the assumption that the knowledge of "g" force requires you to be an Engineer or mathematician is also preposterous.

Why the aversion towards learning basic physics? Ranting about how manufacturers ought to have provided ESP in cars marketed in India is acceptable in a Technical thread, but talking about the basic principle with which the ESP works is way too complicated for a Technical thread.

Are we claiming to be auto enthusiasts just to go oooh and aaah about the flowing lines of a car, or how good the back seat feels over rough roads?

Guess the saying "Ignorance is bliss" is not without founding.

Cheers.
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Old 12th July 2013, 15:06   #63
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by gthang View Post

Why the aversion towards learning basic physics? .
gthang I do understand basic physics and also lateral forces to some extent.

I don't claim that I can do calculations in my head while driving but calculating anything is a moot point if I can not do it in real time.

So how exactly understanding basic physics and knowledge of lateral force I can apply in improving my SUV driving ? Can you please elaborate a bit ?

Few things I already know and practice.

(1) I have a safari which is heavy and has high CG so I should not be rotating my steering too much at high speed. As of now what is too much is as per my driving experience but this too much can be translated to how much if and only if I calculate the numbers which are kind of ruled out.

(2) Jamming brakes and turning steering is a strict no no.
This I know by experience and again no calculation done but experience tells it should be zero steer if brakes are jammed.

Beyond this how exactly and what exactly I can apply from understanding of g forces and basic physics without calculating ?

An unrelated question

If there is a monocoque SUV and a SUV with ladder frame chasis of same gross weight and same height then IMHO centre of gravity for ladder frame chasis vehicle should be lower because weight is concentrated towards the bottom where as monocoque need to have stonger , heavier body shell and weight distribution will be at higher point is it true ?

Similarly if weight and GC is kept same then rear wheel drive should have lower CG then FWD as propeler shaft and differential will shift the mass much lower resulting in lower CG

Am I flawed in my thinking in any way except perhaps RWD ladder frame chasis SUV in our market are twice as heavy as FWD monocoque rival.
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Old 12th July 2013, 15:32   #64
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by amitk26 View Post
So how exactly understanding basic physics and knowledge of lateral force I can apply in improving my SUV driving ? Can you please elaborate a bit ?
Few things I already know and practice.

(1) I have a safari which is heavy and has high CG so I should not be rotating my steering too much at high speed. As of now what is too much is as per my driving experience but this too much can be translated to how much if and only if I calculate the numbers which are kind of ruled out.
I have not ruled out calculations completely. This brings back my OT point of magazines not doing skidpad testing. In this case, you are left to your own experiments to figure out what the limit is. My point was, if you desire to find out on your own, the formula exists, and the test is not too hard to do, provided you have the resources.
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Originally Posted by amitk26 View Post
(2) Jamming brakes and turning steering is a strict no no.
This I know by experience and again no calculation done but experience tells it should be zero steer if brakes are jammed.
ABS was invented just for this purpose. To be able to steer while braking. In the absence of ABS, you have to learn to modulate your brakes to skid,steer,skid,steer,stop (hopefully )!

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Originally Posted by amitk26 View Post
An unrelated question

Am I flawed in my thinking in any way except perhaps RWD ladder frame chasis SUV in our market are twice as heavy as FWD monocoque rival.
Your assumptions would be right for a stationary object. For a rolling vehicle, you are forgetting about the "Suspension". Stiffness and geometry will decide whether the high C of G translates to lower "g" values or not.

I think you are missing the forest for the trees regarding my comments about physics and calculations.

I cannot provide all answers, only share what I feel.

Cheers.
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Old 12th July 2013, 15:35   #65
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by gthang View Post
One thing is common across the board, though. No one likes to hear that their driving can be improved. Seems to be an universal sore spot.

It's ridiculous to think that one can actually calculate "g" forces in your head while driving, and the assumption that the knowledge of "g" force requires you to be an Engineer or mathematician is also preposterous.

Why the aversion towards learning basic physics?
I don't know how your mind works. You twist everything I say into something else.

When I said destructive testing, you could have just asked what I mean by it. Instead you decide to attack my lack of knowledge about the term. I didn't even know it was a technical term, I had used it as an English word. While others understood my intent, you refuse to acknowledge it and go on ranting.

When I say learn the limitation of the SUV by practice since the calculation are beyond most drivers, you call it aversion to improve driving and aversion to learn physics, and so on.

I understand practical physics alright, but I don't understand calculation part. So I am also very frank about my ignorance, and limitations. I won't say I understand, unless I really understand.

Unlike me, you obviously are very knowledgeable and feel everybody can pick the physics and maths behind the dynamics of a moving car. Instead of poking a stick into my large knowledge gap with your very ridiculing comments, why don't you just explain us how it all works?
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Old 12th July 2013, 15:38   #66
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Default re: Evasive manoeuvres & Rollovers?

Slightly OT-

While I agree, there needs to be an objective evaluation of the vehicle in order to "quantify" and compare vehicles, the fact remains, subjective vehicle evaluation is still weighted higher in vehicle testing, specially when it comes to these fields -

a) Ride and Handling
b) NVH
c) Drivability feel

A vehicle can have very good performance figures, that does not necessarily imply it satisfies the performance criteria expected by the user. For e.g. in NVH, two users when subjected to same noise levels, may react differently, the reason being - Psychoacoustics (parameters like shape of auricle, difference in resonance effects at middle and inner ear come in to play).

That is one reason test engineers / drivers are expected to have a good feel of the car. They must be able to communicate with the car when it tries to pass on signals.

Spike
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Old 12th July 2013, 16:04   #67
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by Samurai View Post
I don't know how your mind works. You twist everything I say into something else.
I apologize if you feel that the whole post was directed at you because I quoted you. It was not.

I am under the assumption that personal confrontations are against the rules of Team Bhp. But since a Mod is doing it, I suppose I have to defend myself.
Quote:
Originally Posted by Samurai View Post
When I said destructive testing, you could have just asked what I mean by it. Instead you decide to attack my lack of knowledge about the term. I didn't even know it was a technical term, I had used it as an English word. While others understood my intent, you refuse to acknowledge it and go on ranting.
Am I to assume that you didn't know what destructive testing was from your first post? So, I asked you to check if skidpad testing falls under your idea of destructive testing. Was that a rant?
You could have asked if skidpad testing was destructive or not, if you were not sure of what either skidpad testing or destructive testing was.
Once I explained to you what destructive testing was and where it's used, I have not posted about it since.
Sure, I did not want to patronize you by acknowledging your apology, but didn't know that was a requirement. So when and where did this rant happen?

Quote:
Originally Posted by Samurai View Post
When I say learn the limitation of the SUV by practice since the calculation are beyond most drivers, you call it aversion to improve driving and aversion to learn physics, and so on.

I understand practical physics alright, but I don't understand calculation part. So I am also very frank about my ignorance, and limitations. I won't say I understand, unless I really understand.

Unlike me, you obviously are very knowledgeable and feel everybody can pick the physics and maths behind the dynamics of a moving car. Instead of poking a stick into my large knowledge gap with your very ridiculing comments, why don't you just explain us how it all works?
I am guessing these comments are based on your assumption that my entire post was directed at you, so I shall let it slide.

Since you are browsing the internet to access Team Bhp, I am sure Google is available to you as well, and can provide all the answers you seek, provided you ask the right questions. If I could explain it all, I would.

Cheers

Last edited by gthang : 12th July 2013 at 16:06. Reason: typo
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Old 12th July 2013, 20:41   #68
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by joybhowmik View Post
Student paper. Very limited.

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Originally Posted by chinkara View Post
Regarding Sutripta's question about frozen lake, I understand he is referring to the lower coefficient of friction. But the broader question is would the topple angle be different for all kinds of surfaces? Mud / slush / sand / gravel / grass?
When will one skid? Or topple?

Regards
Sutripta
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Old 12th July 2013, 22:08   #69
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by anachronix View Post
Not just SUV or UV, a bad driver can beat all physics! Its a Honda City that has toppled here!
Absulutely right! Its in the hands of a driver to drive a car safely. The proper technique can do wonders far away from the capability of the vehicle. The Lancer, famous for its stability has once toppled here in an effortless maneuver. The car was doing a nice three digit run, hit a kerb on the roadside, lost control and the next thing on sight is wheels facing the sun.

Last edited by junaid12345678 : 12th July 2013 at 22:11.
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Old 12th July 2013, 22:12   #70
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Default re: Evasive manoeuvres & Rollovers?

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You could have asked if skidpad testing was destructive or not...
Is a moose/elk test destructive testing or not?
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Old 12th July 2013, 22:26   #71
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Default re: Evasive manoeuvres & Rollovers?

The issue is with the nut which was in contact with the steering wheel in most cases

If you cant 'read' your car then its a disaster like gthang said.
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Old 12th July 2013, 23:20   #72
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Is a moose/elk test destructive testing or not?
What do YOU mean by destructive testing?

Cheers
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Old 12th July 2013, 23:44   #73
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by Sutripta View Post
Student paper. Very limited.
...
Regards
Sutripta

Curious to know how you judged that the work is that of a student - the author appears to be a professor emeritus (a very high stature even amongst academicians).

Here is his resume from Virginia Tech. As you can see the paper was written in 2001, while he has been on the teaching staff since 1967.

Or perhaps you wished to dismiss the author's line of reasoning as too simple (like that of a student)- in which case would be good to know if you have a better explanation of the phenomenon?

Last edited by joybhowmik : 12th July 2013 at 23:49. Reason: Removed linked-in URL - as the resume link is sufficient proof of credentials.
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Old 13th July 2013, 09:53   #74
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What do YOU mean by destructive testing?

Cheers
EXACTLY what YOU have defined! Now would you answer the question?
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Old 13th July 2013, 11:22   #75
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Default re: Evasive manoeuvres & Rollovers?

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Originally Posted by Samurai View Post

SUV can survive the evasive maneuver provided the driver is driving in optimal speed for that vehicle. I drive the Grand Vitara at 80-100kmph at regular highways, and get down to 40-60kmph in ghats. This is a speed at which I can do evasive maneuver without losing control, in the Grand Vitara. This is based on my limits, on which no formula can be applied. Each one has to learn his/her own limits in their SUV by practice.
+ 100. Here, many are just bashing SUV for its high center of gravity.....and toppling etc..etc.
I think any driver who understand the limits of his/her machine don't need to panic unless he/she overlook these limits and push it beyond .
So, drive cautiously and enjoy it rather than wasting time and energy in measuring toppling angle and limits of CG.
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