WRC '17 - Does it have to disappoint? Part 2...

In Part 1 of the 2017 season preview of the World Rally Championship, we touched on a surprising lack of excitement, considering the changes afoot. We took a look at the team changes and how the new regulations might affect the performance of the cars. In this segment, the new chassis regulations get the once-over.
So read on, you rally-obsessed peeps...

Is that a classy chassis I see before me? 

 

What's with the wider track?

 I was going to offer a pseudo-technical explanation in answer to that question, but the honest truth is that I have absolutely no idea. At all. So here's some idle speculation instead.

Citoen's C3 WRC weapon in testing.

Wheelbase and track are not absolute values as I'm sure you all know, but instead are relative measures which vary in their ratio depending on what the vehicle is designed to accomplish. It makes sense, therefore, that a vehicle that navigates a great many bends, curves, turns, corners, hairpins and such should have a relatively wide track and relatively short wheelbase to enable it to change direction deftly. (Think racing karts for example).

On the other hand, a high speed vehicle that will rarely if ever change direction would ideally have a relatively long wheelbase and relatively narrow track. (Top-Fuel-type dragster for instance). The former vehicle possessing a wheelbase-to-track ratio approximating 1:1. The latter vehicle would have a wheelbase-to-track ratio of roughly 4:1. Horses for courses, you might say.

But another benefit for a wider relative track will be a flatter stance in cornering, the additional width acting as a natural anti-roll element which also keeps the tyre contact patch flatter while cornering. And a flatter contact patch will provide better grip under most circumstances.

However, a caveat here - a wider track gets its tick in the "This is a good thing, but at a cost" column.

The downsides of a wider relative track will become evident as less directional stability in acceleration and under braking, and the likely greater frontal area increasing the aerodynamic drag at higher speeds (the differences are negligable at lower speeds and non-existent when going sideways). 

Even so, the constructors' designers have mostly resorted to some spectacularly ugly wheel-accomodating blisters in recent times in order to mitigate the frontal drag the wider track generates, and to try and squeeze out a couple of additional kph from their efforts. 

"Hey, rally car designers... in my opinion, it wasn't worth it lads".

Wings and things

Whoever said "I know... let's put big aero devices back onto WRC cars and everyone will remember the good old Group-B days and tune into the telly and everything will be tickety-boo" was clearly smoking something that the local constabulary would frown upon. Besides the inconvenient fact that the audience they want to attract wouldn't know Group-B from a B-cup, rallying will never offer the sort of crash-per-advertiser-minute TV extravaganza as any old monster truck smash-fest.

So moving back into the realms of return on investment, what besides more real-estate for sponsor signwriting will the new aero rules deliver? An excellent question, actually.

Aero kits tend to accomplish two things - to redirect the flow of air around the car in a targeted semi-laminar fashion to minimize drag while avoiding lift, or to simply generate negative lift*. To be successful, the devices must of course perform as expected while at the very least, avoid being actually detrimental to progress. It's not as easy as "stick a dam off the bottom of the nose" and "bung an inverse lift wing out the back", even though that's what the WRC constructors end up doing.

These days its all about computers crunching impossibly optimistic requirements and then wind-tunnel testing the results in a glorified trial-and-error tweak-fest for every decimal point they can extract. So it's not really surprising that all the marques' aero kits look like they were conceived by the same 14 year old kid who's apparently devoid of any aesthetic sensibilities whatsoever.

And unlike drag racing, or the dreaded F1, where the vehicle is nominally in line with the direction of the passing airflow much of the time, a rally car will spend a whole lot of its existence virtually at right angles to the passing air, or being at a distance of many centimetres above the surface that it's supposedly competing "on". 

So calculating the optimal aero package for a WRC car really appears to come down to "So where will the aids actually work, and why don't we just do those, so they at least offer something besides signage space? Those blokes over at VW are pretty much doing the same, eh... All good? Right, your round I think Neville..."

Okay, I exaggerate a gnat's. But while tarmac rallies apparently lend themselves to offering opportunities that benefit more from aero adornments, even on gravel it's clear that a WRC car will also benefit, sometimes greatly from the wings, dams and splitters, expecially on events like Finland and Poland. But that's not really my point. For me the point is that it's open to debate as to whether the new regs will offer any kind of readily-visible improvement that will enhance the WRC spectacle.

Not much scope for a happy camper uptick here I'm thinking.

*Negative lift is just my term for lift applied downwards, from an upside down wing if you like, which counters the tendency of an aerodynamic shape such as a modern car sihouette to lift itself off the driving surface as speed increases.

In the third part of this series, we'll look at the WRC format itself and whether it could be improved. 
By the way, if you feel you have what you believe is a better viewpoint than that offered above, feel free to share it in the comments section below.