The 2022 edition of the American Rally Association (ARA) National Rally Championship is about to start this week with the 36th edition of the Sno*Drift Rally, to be held in Atlanta (MI). The recent introduction of a new version (2022) of the Technical Rules has brought an important step ahead in terms of aerodynamics to a Championship with already open regulations. This is our review of the aero novelties in the new rules.
By the end of the 2021 season, and “in view of the evolving aerodynamic standards in rally around the world”, the ARA announced the updating of the bodywork rules for the next season. The result was the 2022 version of the ARA Rally Technical Rules, which was presented in early January. The most important novelties consisted in authorising the use of additional aero parts in most of the cars, mainly those included in the most popular categories of the Championship.
B.Morris/R.Scott, Mitsubishi Mirage RS, 2021 Southern Ohio Forest Rally, 19th – picture by Ganesh Nagarajan
Changes affecting all car categories
The new rules set some modifications for the rear wing, the most important being the use of adjustable wings. Only restriction is that adjustment is only allowed from outside the vehicle while the car is stationary.
Also, a new restriction has been added with respect to the wing endplates, that now will have a minimum section of 3mm.
The new rules also allow for other modifications, such as the addition of air intakes and vents at the hood (bonnet), as any devices or addition forward of the windshield must be below the line of the hood when viewed from the side. They cannot define the plan view and must fall within it.
Also, aerodynamic plates or elements extending from major body surfaces are allowed, having a 10 mm minimum section width at the outside edge. This means that dive planes, winglets or similar devices are also allowed.
R.Rethy/R.Rethy, Subaru Impreza Outback Sport, Trespassers Wil Regional Rally 2021, 1st – picture by Jason Swoboda
Changes affecting Open Classes (Open 4WD, Naturally Aspirated 4WD and Open 2WD)*
One of the main novelties at the front is the possibility of the addition of front splitters, as the new rules allow modifying the front air dam by downward or forward extension. The restrictions in dimensions are:
– they cannot extend any more than 60 mm forward of the furthest point forward of the front bumper face at any point, and
– they must fit within the front overhang and total length percentages and may be no wider than the front fenders.
The introduction of a front splitter contributes to generating some downforce at the front (as the air dam is a high pressure area due to the impact of the airflow). But it also limits the amount of air flowing under the car, which contributes to accelerating it, thus reducing pressure under the car (and increasing downforce).
The new rules also allow some important front modifications for cooling purposes, affecting the radiator, auxiliary heat exchangers and front brakes. The radiator opening of the front bumper can be enlarged or reduced. Also, additional openings may be added for the sole purpose of providing cooling airflow to the front brakes or auxiliary heat exchangers located in the front engine compartment.
S.Burke/M.Brady, Ford Escort Mk2, 2021 Southern Ohio Forest Rally, 10th – picture by Ganesh Nagarajan
Another important novelty is the introduction of rear diffusers, with the only restrictions that:
– must be located below the lower luggage opening in their entirety, and rear of the centerline of the rear wheels,
– may define the plan view but cannot extend rearward more than 50mm of the rearmost point of the rear bumper, and
– must fall within the approved body and overhang dimensions.
Changes affecting Limited Classes (Limited 4WD and 2WD)
Underbody protection can be added, provided it intends to serve no other purpose. But, even with that only purpose, they contribute to having a smoother airflow under the car, allowing air to flow faster.
The implementation of the new rules will benefit not only the factory team (Subaru) taking part in the Championship, as well as those teams driving machines derived from the WRC (except Rally2 cars) but also to the legend of private teams driving all types of rally cars, as many of them will surely undertake DIY process to improve the aero of their cars.
*Open classes include WRC, modified Rally2, AP4, and Proto cars, amongst other