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What we can learn from WRC’s first Rally1 photos

Finally, we have caught a glimpse of all three World Rally Championship teams’ first interpretations of the 2022 Rally1 regulations. Hyundai, M-Sport Ford, and Toyota have all commenced their hybrid test programmes with images coming through of each manufacturer’s vehicle.

In this article, Rally Insight will look at three key areas that have visibly changed from Rally1’s World Rally Car predecessor: aerodynamics, safety roll hoop, and hybrid module venting.

Aerodynamics

It is starting to become clear how “trimmed down” Rally1 aerodynamics will be. Gone are the intricate front dive planes, winglets, and vented arch exits. The deep, beefy diffusers from the 2017 to ‘21 World Rally Cars have disappeared too.

The front splitter and side skirts remain and will limit air flow beneath the car while wheel arches look more like what we’re used to seeing on a Rally2 car.

So what does all this mean for car performance in rallying’s highest level?

Much, much less downforce.

Excluding the rear wing, there are no other downforce inducing elements. It’s a stark contrast to the multi-level dive planes currently on the 2021 Hyundai i20 WRC’s front bumper. Or indeed the complex winglet design above the Toyota Yaris WRC’s front arch.

All these elements generate front downforce and they have simply been scrapped for 2022.

Couple that with a considerably smaller diffuser (if there even is one) and you are left with a completely different car.

The reduction in aerodynamic devices means less force acting between the tyres and the stage surface so the car will have less grip and lower cornering speeds.

Even the simplified arch design will reduce the car’s downforce. Teams had learned through the 2017 WRC regulations how vented arch exits reduced the air pressure within the wheel arches.

Unable to vent arches in 2022 results in high pressure, turbulent areas within wheel arches which creates lift, opposite to downforce.

The removal of front aerodynamic elements will reduce the amount of front-end downforce. It looks like a large rear wing will be maintained into next year so it is fair to say the front-rear aerodynamic balance, or Centre of Pressure, will move rearwards.

Having less downforce at the front of the car will give the car a tendency to understeer.

Another point to note is the addition of Rally1’s 100 kg hybrid power unit in the rear half of the car. This shifts the car’s mass distribution rearward.

With both the Centre of Pressure and mass distribution shifting closer to the rear wheels in 2022, car balance characteristics will be completely different.

It may help rear-end stability at high speed but it will also make the car harder to turn into slower speed corners.

How the rear wing works will also change with the loss of front aerodynamic devices. These devices help control the direction of streamlined air flow towards the rear wing. This improved the amount of downforce generated by the rear wing.

Now, teams will have to design a new rear wing to work effectively on its own or perhaps adapt body panels to improve air flow around the car.

Safety roll hoop

A key aspect of WRC’s 2022 regulation changes is improved safety with a new safety cell playing a key part. The safety cell’s double roll hoop is visible in the photos from early Rally1 tests.

While an increased roll cage structure improves safety it could also improve the performance of the car’s chassis.

WRC’s move to a spaceframe chassis should give teams more control over its design. Maximising the chassis’ rigidity and torsional stiffness will improve the car’s overall handling and predictability.

Minimising any chassis compliance will improve the accuracy of set-up changes as the car’s reactions to road surfaces will be dealt purely by the suspension components rather than a flexing chassis.

Obviously the chassis design of a World Rally Car is already at an incredibly high level but an engineer will always be searching for more.

Picking suspension mounting points, or suspension geometries, will also be a key aspect of designing a spaceframe chassis.

Where suspension components are mounted to the chassis plays a big part in camber, caster, and roll centre characteristics. Again these mounting points are high load-bearing locations so combining their locations with strong parts of the spaceframe is important.

Hybrid unit venting

The most noticeable addition to the appearance of Rally1 cars is the cooling vents required for the hybrid unit. Like an internal combustion engine, the battery pack also needs to be cooled.

Side vents are visible on all three test cars, although Hyundai sneakily edited theirs from its reveal photos.

Videos show that Hyundai’s side vents are much narrower than those on Toyota’s GR Yaris test car.

This will be a key design area, confirmed by Hyundai’s secrecy, and will play a huge part in the 2022 title race.

The narrowest vent will keep the car’s frontal area as small as possible, therefore keeping drag losses to a minimum. But if the vent is too small and doesn’t cool the hybrid unit sufficiently then teams will be looking at a list of hybrid unit failures and early retirements.

However, if designers play it too safe with a big vent, they’ll haemorrhage stage-time to their rivals with poor high-speed performance.

Channeling the air around the power unit to enable its cooling will also be a key design consideration. Streamlined flow will be sought after as turbulent flow not only creates drag but could effectively block air flow through cooling pipes and decrease the cooling effect.

Teams have also designed a rear bumper vent to expel the hot air from the hybrid unit area. While no released photos show this area of the car, screenshots from testing videos (like the Toyota above) show what to expect.

Perhaps engineers can utilise this hot air exit along with the underbody flow to regain some of the downforce lost from no longer having a large diffuser.

Test, test, test

Now that each team has a test car fit for the stages, engineers will be crawling through data to evaluate how their designs are performing.

With significant changes to car layout, chassis design, aerodynamic features, and power delivery; there is plenty of scope for development before lining up in Monte-Carlo next year.

As always, the massive challenge is making the package work effectively in the heat and altitude of Rally Mexico, the snow of Rally Sweden, and the bone-shaking Acropolis.

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Photos from M-Sport and Hyundai Motorsport

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