DIY Frontal Downforce

Myself and the other male members of my wider family attempt to go to the 24hr hour race at Le Mans every year for a lads weekend away. It’s very good fun, and after a few beers we don’t always watch that much racing 😉

Last year we went a couple of days early and so I took the opportunity on the Friday to join the masses and do the pitwalk, and me being me, it got me thinking…

Walking past all the garages, most of them had bits of bodywork left out front while the engineers did all their last minute adjustments on the internal gubbins of their respective machines. If you’re at all technically minded it’s fascinating.

Anyway, with the bodywork off, you get to see a lot of the ducts and shapes that guide the airflow, and if you have even half an idea about aerodynamics, or even a bit of imagination you can see how it all works.

I’m sure the maths behind it all is pretty complex, actually I know it’s pretty flippin’ complex. I studied applied physics at Uni and I’ve been scratching my head thinking about boundary layers, flow gradients and cross sectional areas, whilst trying to work out the equations from first principles. Then again, the whole thing is in three dimensions too, so why not use the engineer’s other rule (of thumb), if it looks good it probably is.

Have a look at the picture above. The splitter is the shelf bit at the bottom that sticks out and splits the air flow in two. What it does is direct smooth air beneath the underside of the car. The reason it has a raised bit in the middle, is to prevent this happening:


Fortunately no one was hurt in the incident, which I bet Mercedes were very glad of, considering what happened in 1955. The driver was unscathed, and you can see him in action most weekends on your telly, as it was the very talented Mark Webber behind the wheel.

front diffuserUnderneath the splitter is shaped a bit like a diffuser, for the same effect – to decrease the air pressure under the car, so the air pressure above it presses the car down, otherwise known as downforce!

However, unlike the rear of the car, there is no easy place for the air to vent, so they vent out to the sides, “possibly the wheel well) like this picture here.

So where’s the DIY?

Well my boss has a kit car with a flat underside…

(I’ll keep you posted!)

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