AUTO TECH AND ROAD SAFETY

Driving through crosswinds

Driving through crosswinds image

Text: Tito F. Hermoso / Photos: Kelvin Christian Go, AutoIndustriya Team, Mercedes-Benz Press | posted July 23, 2014 18:13

Dealing with storms and crosswinds

Year in, year out

The onset of the Monsoon season always brings on timely reminders on how to stay safe. Auto clubs, consumer groups, oil companies, car dealers, tire makers, wiper makers and the like never fail to rehash time-tested and recycled tips. Now this same Southwest monsoon or Habagat, also brings in typhoons and with it. strong winds. Seasonal winds do buffet our country at other times of the year - descending at Christmastide are the cooler Siberian winds that come with the Northeast monsoon – so-called Amihan - and the hot Pacific Easterlies that arrive around Holy Week, simmering the start of summer. But of all these winds, the most hazardous are those wrought by typhoons that come along during the 5 month long Habagat season.

Incoming!

No one would want to be caught on the road during a typhoon, but with judicious caution, one can still drive safely. In a city's broad avenues, one can be assailed by descending gusts. Along parkways and avenues, any debris from billboards, buildings and trees are instantly transformed into lethal wind driven projectiles. City blocks, like Legaspi and Salcedo village, where canyons of skyscrapers funnel the storm's gusts into fierce screaming banshees, toppling parked cars and trucks.

Door blown out

In inclement weather, one already instinctively drives slower, even if one didn't want to, as the rain diminishes visibility. Unless necessary, stopping to alight is postponed until a drier and safer porte cochere can be found. In a storm situation, one should always be cautious in opening the door lest a strong gust tears it from its hinges.

More ground clearance, more lift

Out on the expressway, one also runs the risk of wind driven projectiles but the greater and more constant risk is the effect of gusts of wind that can threaten to dislodge your vehicle's position on the road and if you're unlucky, flip your vehicle over. Vehicle behavior under aerodynamic stress is dependent not only on the wind's angle of attack and the vehicle's speed but also on the vehicle's aerodynamic profile. Low-slung rakish cars, present less of a wind catcher compared to a tall boxy vehicle. Vehicles, like SUV's with high ground clearance, the ideal for flood wading, present a tempting silhouette for the typhoon wind to cause 'lift'; i.e. literally, wind induced pressure on the underfloor that could 'lift' the vehicle airborne. Witness how strong winds easily mangle and topple those boxy square shouldered 22-wheeled freight juggernauts.

Storm aftermath

Storm chaser? Not!

What to do? If one can be updated by media or Navigation on the severity of the storm, one might pull over in a safe place to let the storm tide over. If one must proceed, the strong winds alone are a disincentive to try to challenge the storm to a speed race. Slowly and cautiously, instead of fast and furious, will be the winner's strategy of the day.

Aerodynamics

Besides altered driving modes, there are ways to improve the aerodynamic profile of a vehicle. Improving your vehicle's aerodynamic profile already derives benefits for handling – what racers call downforce on fast curves, smoother cleavage of the air at high speed and with it comes improved performance and fuel consumption. These aerodynamic kits are common for most kinds of cars which now include SUVs and AUVs. Usually made of tough but flexible plastics, these are optimized if fitted as an entire kit composing of front and rear spoilers, side skirts and if needed, wheel arch fairing and fender splitters. Further customization is possible through outfits like A-toy bodykits, an art form which can even totally change the way your car looks.

TRD aerodynamics

 

TRD and Modulo

There are numerous after market kits available for cars, but the main brands are also touting their OEM [original equipment manufacturer] brands. Eight years ago, Toyota began marketing such kits for its ASEAN made models, under the TRD high performance badge. To revive its sporty roots, Honda has recently been rolling out Modulo kitted versions of its bread and butter 'civilian' cars. What works for speed, works for finessing the wind flow, even in a typhoon- or so it seems.

Storm testing

Over the years, we have had typhoon experience in comparing standard model to aerodynamically enhanced models with such kits. Just as at speed or on a racing circuit, the aerodynamically improved version really feels planted on the road as it is pummeled by the typhoon's gale. Even if one is hit by a bow wave or a deflected gust from a juggernaut or coach, the sideways nudge is felt but easily corrected. Specifically tested many years ago were comparing standard Toyota models to TRD fitted Altis, Innova and Fortuner. Honda's Modulo fitted Civic, City, CR-V and CR-Z also impresses in making the added stability felt. Caution: one should make sure these kits are professionally mounted. With haphazard fitting, one may even experience more dangerous lift and yaw than if none was fitted previously.

Scientific testing

Another watchword is wind tunnel testing. Some ASEAN producers are content with circuit testing at Prince Bira Circuit, but nothing beats scientific wind tunnel testing subjecting the car and spoiler to all angles of wind approach. These other branded aero-appendages may look good but may be either too stiff or too flexible in the wrong areas which would actually worsen the car's aerodynamics, making it unstable.

Foha and Kamei

Back in the 80s, when standard cars had even cruder aerodynamics, Foha of Austria and Kamei of Germany sold excellent wind tunnel tested aftermarket plastic aerodynamic appendages for many popular Japanese cars. They performed as advertised and the improvement was major.

Oldies

What about older cars? In general, one can expect better storm 'swerve' resistance abilities with the later more aerodynamic cars. For example, a 2006 Peugeot 206 could be driven through blustery and stormy day with less drama, less involuntary shifts in steering direction or hardly any steering corrections than a 2003 Toyota Vios. The Vios, with its more rakish format would not only feel more 'planted' in crosswinds, but will also have quieter NVH than a 1997 Honda City. In turn, the City, with its front wheel drive, will feel more secure than the boxy and blunt 1968 Mercedes 200D/8, even if the Mercedes is heavier.

Isuzu Crosswind 

Crosswind, by Isuzu

On the other hand, a 2002 Isuzu Crosswind diesel, boxier, heavier, slower and sitting on old fashioned rigid axle, semi-elliptic rear springs and ladder frame, will resist sideways gusts of winds by its sheer weight alone. The Crosswind is noteworthy because the ride and roadholding of its old style chassis is highly dependent on the tires. Isuzu has wisely specified 60 series Michelin LTX. Now these tires are big enough to look like balloon tires. With its fat sidewalls, the Michelins take up the burden of softening the ride, of which, in turn, shows how important it is to maintain correct tire pressures.

Pressure on the tires

Isuzu, like all AUV makers, recommend tire pressures far higher than a regular monocoque automobile. It is a testament to the Michelin tires and a function of its fat sidewalls that the ride is never harsh. But owing to its weight and configuration, the Crosswind will never handle like a City. The squishy ride-biased sidewalls will prevent that. The Crosswind is living proof that one should strictly maintain factory approved tire pressures. Reducing or deviating tire pressures from recommended, will cause the car to be unstable, even without any storm crosswinds. Under inflated, the Crosswind's weight is supported by the tire sidewall gone wobbly. And a tire contact patch, critical during stormy days and soaking highways, akin to a dough-nut resulting in very poor traction and steering control; hence the Crosswind will sway and pitch when blown by the winds. Over inflating shrinks the tire contact patch to the width of a bicycle tire – again a No-no for one's dire need for wet traction during a typhoon. Properly inflating the tires, allows the tire to bear the weight of typhoon wind downforce in addition to 2 tons of Isuzu metal. With the wrong inflation, the Crosswind's steering will end up wandering in a straight line, typhoon crosswind or not.

Crosswind Assist

Aerodynamics for the long haul

Aerodynamics also works well for the bottom line of long haul truck fleets around the world. Trucks fitted with dome like canopies over the prime mover's roof smoothen the air flow over the towed trailer. Fairings around the wheels and spoilers also function much in the same way as they do in competition cars. Electronic stability aids, with yaw and pitch sensors, as used in cars are also found in trucks sold in the EU and USA.

Expressway gale abatement features

Road makers and tollway operators also have a role to play in mitigating the dangers of driving when strong crosswinds are imminent. The winds of recent typhoon Glenda caused the closure of the Skyway elevated for most of the day. Some expressways fit wind deflective barriers on sections, like viaducts over river gorges. The sound barriers fitted on some expressways that pass through residential areas double function as wind deflectors too.

Wind sac

Wind sac; direction and speed

Besides informing motorists of gusty winds and their location via electronic message boards, tollway operators in most countries fit wind sacs. Usually installed on masts to catch the wind and within the video coverage of CCTV cameras, these orange and white fabric cones show the angle and speed of the wind. They are commonly found along seaside, rolling plains and alpine expressways. These wind sacs, if fitted on our local tollways, would come in handy when one gets caught driving by any one of our annual quota of 26 storms a year.

Thus when it comes to wind speed and aerodynamic stability, the best practices of the aviation industry and motor-sports are a sure benefit whenever one is forced to drive in typhoon conditions.