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Old 11th April 2010, 10:12   #16
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Spike: good report.

How about weaving a car and what is the max speed at which one can do it without the tyres screeching?

IMO, learning to weave a car lets one understand the behaviour of the car from handling to steering response to road grip and driver confidence.

And a slalom is done once, a lane change is half a slalom and a multiple slalom is ???
The speed at which tires screech cannot be generalized as it depends on a various factors. Tyre screeching depends on factors like slip angle, camber thrust, lateral acceleration, traction available at wheels etc. Lane change and slalom are not the same, in a slalom the pitch in a track remains the same whereas in a lane change/elk test the pitch varies. However, i agree that they look similar.

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Old 11th April 2010, 12:51   #17
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in a slalom the pitch in a track remains the same whereas in a lane change/elk test the pitch varies.

How do you vary the pitch?
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Old 11th April 2010, 13:54   #18
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How do you vary the pitch?
For slalom test, this value remains constant throughout the obstacle, but this constant value depends on the type/wheelbase/dimensions of the vehicle being tested.

For Elks/lane change test, the pitch varies throughout the section as defined in IS standards.

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Old 11th April 2010, 17:58   #19
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For slalom test, this value remains constant throughout the obstacle, but this constant value depends on the type/wheelbase/dimensions of the vehicle being tested.

For Elks/lane change test, the pitch varies throughout the section as defined in IS standards.
Spikey man, Forget the IS standards. I want to know HOW one varies the pitch in the ELK test?

Personally, I have pushed most cars / jeeps / gypsies / Storms through whatever tests I know [I'm no qualified T driver but an enthuthiast like you]

I value the vehicle behavior especially high speed dynamics, steering response, body roll as well as tyre grip levels. It is an eye opener to understand vehicle dynamics without involving "physics"

Now, please tell me how one varies the pitch on a lane change test?
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Old 11th April 2010, 18:51   #20
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Now, please tell me how one varies the pitch on a lane change test?
Simple, first section will be of short length with a width = X1 times the width of the vehicle + run off area, second section will be longer compared to first one with section width X2 (X2>X1) times the width of the vehicle and so on. First increase the length and section width of the track gradually and then come back to the dimensions (similar to first section) at the final section i.e. X1. This is how it is done generally. See the pics i posted earlier and you will understand.

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Old 13th April 2010, 11:17   #21
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Wow, finally the thread is moving thanks to Spike and headers.

One question here. Both the elk and slalom tests, if I am not mistaken are done by real human beings as drivers. This may result in variances in data due to human error, varying capacities of a driver as such and other non measurable parameters. How are those neutralized?

PS: Pl accept my apologies if the questions sound stupid.
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Old 13th April 2010, 12:04   #22
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One question here. Both the elk and slalom tests, if I am not mistaken are done by real human beings as drivers. This may result in variances in data due to human error, varying capacities of a driver as such and other non measurable parameters. How are those neutralized?

PS: Pl accept my apologies if the questions sound stupid.
Good question (no question is stupid).

You are right, there will be variances due to driver interface/human errors. In order to minimize this, the test is conducted by atleast 5 experienced drivers/test engineers, and then statistically co-related. Every vehicle testing agency has a pool of qualified test drivers/engineers who are used for this purpose.

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Old 13th April 2010, 12:08   #23
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This is a great stuff.

Thanks Devdath for starting this. And Thanks Dabhar sir, CPH and Spike for pouring in. I am all ears. Already subscribed to this one. Keep it going.
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Old 13th April 2010, 12:16   #24
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Thank you for you answer Spike.
So is vehicle testing a part of the vehicle validation process?
You mentioned that the track must be dry and hard for the elk and slalom tests. Which I guess is somewhat like "ideal test conditions". How and what testing is done for "real world" conditions then?

Waiting for your inputs.
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Old 13th April 2010, 12:22   #25
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Great thread guys!
But still no description of ARAI? When does ARAI comes into picture?
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Old 13th April 2010, 12:26   #26
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Originally Posted by n.devdath View Post
Thank you for you answer Spike.
So is vehicle testing a part of the vehicle validation process?
You mentioned that the track must be dry and hard for the elk and slalom tests. Which I guess is somewhat like "ideal test conditions". How and what testing is done for "real world" conditions then?

Waiting for your inputs.
Nice question again, Vehicle testing is the most integral part of the vehicle validation process. For simulating real world conditions vehicles may be taken to geographical regions which offer such terrains/conditions, or such conditions are simulated in test tracks e.g.water sprinkling etc.

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Old 13th April 2010, 12:49   #27
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Nice question again, Vehicle testing is the most integral part of the vehicle validation process. For simulating real world conditions vehicles may be taken to geographical regions which offer such terrains/conditions, or such conditions are simulated in test tracks e.g.water sprinkling etc.
Spike
So, what tests, and to what extent or depth are they done and in what sequence when developing a vehicle? For example, the elk and slalom tests would probably give an idea of the handling, the stress bearing, the flexing and body roll characteristics of a vehicle which I guess, implies the suspension, the tires, the structural rigidity, and the steering qualities along with driver ergonomics and line of sight.

How are the other aspects of a vehicle viz;the engine, drivetrain/drive line, electricals etc tested?
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Old 22nd April 2010, 16:38   #28
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Originally Posted by n.devdath View Post
So, what tests, and to what extent or depth are they done and in what sequence when developing a vehicle? For example, the elk and slalom tests would probably give an idea of the handling, the stress bearing, the flexing and body roll characteristics of a vehicle which I guess, implies the suspension, the tires, the structural rigidity, and the steering qualities along with driver ergonomics and line of sight.

How are the other aspects of a vehicle viz;the engine, drivetrain/drive line, electricals etc tested?
Vehicle dynamic tests upto some extent can be simulated using CAD tools like Simulink/Adams/Carsim, but actual feedback only happens with instrumentation on prototypes. For a new product this evaluation starts from Engineering Prototype stages. Once a baseline performance is achieved fine tuning is done by using different shock absorber rates, spring rates, tyres with varying belt angles, tread pattern, cornering stiffness, roll stiffness etc. But for this to happen first the basic suspension and steering geometry must be zeroed in. You can always tweak if the baseline performance is OK.

For engine and driveline there are plenty of tests which focus on Engine Cooling, Air Intakes (intake depression), Intercooler performance, Alpine (Gear Jump out test), Hot rod shift for manual transmissions, Roll back/forward, Water ingress, Axle scoring/noise etc.

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Old 2nd September 2010, 09:53   #29
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A few queries on this wonderful thread (thanks, Devdath, for starting this )

1. Road Test : How many thousands of kilometres are normally done before approval ? Are there any regulations on this ?

2. The periodic maintenance manual : Is this directly linked to the observations made during the road test ?

3. Individual modules : are modules such as gearboxes and engines made to undergo separate tests, for so many hours of operation ?
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Old 2nd September 2010, 11:03   #30
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A few queries on this wonderful thread (thanks, Devdath, for starting this )

1. Road Test : How many thousands of kilometres are normally done before approval ? Are there any regulations on this ?

2. The periodic maintenance manual : Is this directly linked to the observations made during the road test ?

3. Individual modules : are modules such as gearboxes and engines made to undergo separate tests, for so many hours of operation ?
1. 100000 km as a thumb rule, also depends on the manufacturers confidence on his product. There are no regulations, this depends only on the manufacturers discretion.

2. Yes it is.

3. Yes, usually an endurance, durability vehicle is run for only endurance, durability or reliability whereas separate vehicles are used for performance trials. Nature and amount of testing depends on the kind of design change, and varies on case to case basis.

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