Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 15th August 2016, 17:23   #16
Distinguished - BHPian
 
condor's Avatar
 
Join Date: Jun 2006
Location: Speed-brkr City
Posts: 9,914
Thanked: 3,063 Times
Default Re: Car swaying on highway - Effect of crosswinds?

Quote:
Originally Posted by apachelongbow View Post
However a parked Storme oscillates a bit when a truck or a bus pass by at high speed in close quarters.
That would be because of the road / foundation not being firm enough.
condor is online now   (1) Thanks Reply With Quote
Old 15th August 2016, 21:17   #17
BHPian
 
Join Date: Sep 2007
Location: bangalore
Posts: 91
Thanked: 34 Times
Default Re: Car swaying on highway - Effect of crosswinds?

I have Waggy F10D, Recently i was crusing on highway(BLR-HYD), even though i was at 80-100 speeds. I could feel significant Lateral movement, due to crosswinds, lateral movement gets worse especially, while overtaking HCV's.

Worthy to mention: we are 3 adults + 2 Kids with lots of luggage, still maybe because due to tallboy design, significant lateral movement.
navrddy is offline   Reply With Quote
Old 15th August 2016, 23:01   #18
Senior - BHPian
 
vnabhi's Avatar
 
Join Date: May 2007
Location: DC -> DC
Posts: 5,062
Thanked: 1,056 Times
Default Re: Car swaying on highway - Effect of crosswinds?

Tall vehicles like XUV, most SUVs and tall boys like WagonR, Santro and Celerio sway like hell in heavy cross-winds, and also when passing a large truck or bus at high speeds.

But there are some notorious spots where even sedans and 'great-handling' hatchbacks get affected. Once such spot is near the Penukonda windmills on the Hyderabad to Bangalore highway. I travelled last month on my Figo. Luckily a bhpian had travelled a couple of days before, and also another who'd ridden a bike on the previous day. Owing to their narration, I was prepared for that spot. At triple digit speeds, i felt the Figo had lost air on the front right at some spots, and on the front left at others spots. I dropped speed to below 100 and kept driving in the pitch dark for around 10 kms. After that everything was normal! Phew, some relief that was!

While on this, even on the Hyderabad ORR there are some spots with heavy cross-winds. I experienced it last week on my Fiesta. When I was overtaking a Merc SUV at triple digit speeds (legal on ORR), I suddenly felt the car drift from the center lane towards the divider. I quickly dropped speed and understood why the SUV had also dropped speed. But after a few kms, I could reach very high speeds without loss of composure.

To sum up, even the best-handling sedans and hatchbacks are no match to the mighty forces of nature. Drive with caution and be safe.

While on this topic, I wonder how the 'pull-drift' compensation on the new Fiesta would compensate for such cross-winds. I am not sure if that really works, but new Fiesta owners can perhaps chip in.
vnabhi is offline   Reply With Quote
Old 17th August 2016, 22:01   #19
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Kolkata
Posts: 3,304
Thanked: 1,693 Times
Default Re: Car swaying on highway - Effect of crosswinds?

Much has been said of crosswinds, but do
a) drive anothersimilar vehicle to find out if yours is different.
If so, also check out
a) tyres
b) steering geometry, and worn out parts.

For tyres, best to swap with known good tyres for testing purposes.

Quote:
Originally Posted by Rahul Bhalgat View Post
The crosswinds what we usually come across, can make the car roll on its suspension but it cannot make it drift laterally. Rubber (tyre) has fairly good amount of grip on the road (co-efficient of friction at least 0.5). So a lateral force of at least half of the car's weight will be needed to displace the car laterally. With ambient air density of around 1.2 - 1.25 kg/cu m, very high crosswind speeds will be needed (more than 200 kmph for Alto) to displace the car laterally.
Vehicle is not static.

Regards
Sutripta
Sutripta is offline   Reply With Quote
Old 17th August 2016, 22:47   #20
Senior - BHPian
 
khoj's Avatar
 
Join Date: Sep 2008
Location: Dilli
Posts: 2,664
Thanked: 1,185 Times
Default Re: Car swaying on highway - Effect of crosswinds?

Completely agree!!

2008, swayed by popular recommendations, picked up a spanking new SwiftZxi from "My Car" just off the BOM-Poona expressway and as I drove back to Bombay, I literally cried.
The crosswinds on the curvy stretch before the first toll made the Swift flutter like a dried leaf.

The next two purchases though very unpopular (Cedia & Linea TJet) are rock steady in even the gustiest of winds.

Quote:
Originally Posted by GTO View Post
Just wanted to add that some cars don't appear to be as affected by crosswinds as others.
khoj is offline   Reply With Quote
Old 17th August 2016, 23:07   #21
BHPian
 
Join Date: Apr 2011
Location: Pune
Posts: 471
Thanked: 370 Times
Default Re: Car swaying on highway - Effect of crosswinds?

Quote:
Originally Posted by Sutripta View Post

Vehicle is not static.
Yes. But even the kinetic friction coefficient between tyre and dry pavement is more than 0.5. So the crosswinds (that we usually come across) alone cannot cause lateral movement of the vehicle unless some additional lateral force is generated because of tyre - road interaction. Properly aligned, balanced and rotated tyres having proper grip won't allow the car to sway laterally.
Rahul Bhalgat is offline   Reply With Quote
Old 18th August 2016, 20:26   #22
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Kolkata
Posts: 3,304
Thanked: 1,693 Times
Default Re: Car swaying on highway - Effect of crosswinds?

^^^
We are not talking of dragging a tyre across a surface.

If you park your car on a camber, it will not slide down. But if you start driving, with the steering in the same position as when you were driving on a level plane, you will start running down the camber.
Same with crosswinds. Because it comes in gusts, it needs constant correction, and is immediately apparent.

More than the weight of the car, care in aerodynamic design is necessary. I don't think the Alto K10 (old original version) ever saw the inside of a wind tunnel.

Regards
Sutripta
Sutripta is offline   (1) Thanks Reply With Quote
Old 19th August 2016, 11:48   #23
BANNED
 
Join Date: Mar 2006
Location: mumbai
Posts: 1,893
Thanked: 1,780 Times
Default Re: Car swaying on highway - Effect of crosswinds?

take a look at this NZ article. http://www.drivingtests.co.nz/resour...-strong-winds/
Its surprising to see how a heavy trailer can be pushed off due strong cross winds. The slab sided area is to blame. Thinking about this I was wondering why my Storme doesn't feel that susceptible to crosswinds, then I realized that it is not really slab sided, infact the side is quite steeply sloped towards the roof, unlike a Scorpio or a Sumo. Maybe that and some aerodynamic designing could be the reason there is not much effect felt.
A quick question: If there is a heavy crosswind, will opening all windows, help lower its effect since the air is now being blocked by a lesser surface? Or will it make the car more imbalanced?

Edit: http://www.instructables.com/id/Meas...-car/?ALLSTEPS An interesting article to measure the drag coefficient of your car.

Last edited by apachelongbow : 19th August 2016 at 11:55.
apachelongbow is offline   (1) Thanks Reply With Quote
Old 19th August 2016, 15:04   #24
BHPian
 
Join Date: Apr 2011
Location: Pune
Posts: 471
Thanked: 370 Times
Default Re: Car swaying on highway - Effect of crosswinds?

Quote:
Originally Posted by apachelongbow View Post
A quick question: If there is a heavy crosswind, will opening all windows, help lower its effect since the air is now being blocked by a lesser surface? Or will it make the car more imbalanced?
Opening the windows will reduce the effect of the crosswind. The window area has a considerable contribution to the total lateral area.

And crosswinds are not expected beyond 4 - 5 km travel at a stretch (correct me if it is not so). So for those 5 minutes, increased drag (due to open windows) shall not matter much.

The video in the NZ site also shows that the truck swung due to heavy crosswind and large and tall lateral area. It did not sway laterally.

I appreciate the truck driver's presence of mind in taking a sharp right turn to restore the balance. The toppling wind force was countered by the centrifugal force because of turn.

Last edited by Rahul Bhalgat : 19th August 2016 at 15:10.
Rahul Bhalgat is offline   (1) Thanks Reply With Quote
Old 19th August 2016, 17:34   #25
BHPian
 
vsathyap's Avatar
 
Join Date: Aug 2011
Location: BengaLuru
Posts: 261
Thanked: 607 Times
Default Re: Car swaying on highway - Effect of crosswinds?

Quote:
Originally Posted by Sutripta View Post
but do
a) drive anothersimilar vehicle to find out if yours is different.
Quote:
Originally Posted by khoj View Post
.... and as I drove back to Bombay, I literally cried.
The crosswinds on the curvy stretch before the first toll made the Swift flutter like a dried leaf.
Quote:
Originally Posted by Sutripta View Post
More than the weight of the car, care in aerodynamic design is necessary. I don't think the Alto K10 (old original version) ever saw the inside of a wind tunnel.
For example, I owned the prev gen (classic Alto K10 2010 edition) and it did not sway too much. Yes - the effect of overtaking a large vehicle was definitely there but not too much.

Now, the new K10 that I currently own, (although having the same engine and platform, etc.) its a different machine altogether. The new K10's suspension is pretty soft - the body roll can be felt very VERY significantly compared to the old K10 and the ride is extremely bouncy, even with full luggage and load. The new K10 fares quite poorly on uneven roads and now, to add insult to injury, this swaying caught me off guard. Agreed that the tramlining effect could also have played a big part in how the car felt but at some points, it was so bad that while overtaking, the car literally had a mind of its own while picking the direction of travel and hence I had to constantly do micro adjustments to the steering.

This is why I wanted to know whether something is seriously wrong with the car or if this is a common phenomenon. At least, after all these posts, I can be happy to know that even bigger vehicles have been suffering from cross winds.

It feels exactly like this - when a wave hits a boat's side while travelling parallel to the wave - that moment of impact - the entire boat (floats) sways a few inches in the direction of the wave and later settles down - it was the same with the car, although the lateral movement was in millimeters instead of inches. But, because of the high speeds, this small movement was getting translated to a very large lateral "sway".

I think I'll have a definite answer when I upgrade stock tyres to better, fatter ones when the current ones are at the end of their life.
vsathyap is online now   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Nepal: Driving through the East West Highway (Mahendra Highway) Samratrek Travelogues 3 24th July 2016 12:26
Crosswinds - A Biker Honeymoon in New Zealand! praful Travelogues 32 6th October 2015 01:25
Motorcycle: Swaying Problem Wind splitter Motorbikes 32 25th December 2014 10:08
Modded Santro's day out on the Highway! (Universal K&N Effect) Samurai Modifications & Accessories 65 17th June 2010 16:24
NANO effect and EURO effect in Small Car market allwheeldrive The Indian Car Scene 8 15th June 2009 22:29


All times are GMT +5.5. The time now is 14:35.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks