Technical Analysis: WRC Cars 2017

**NickRally** · 20th February 2017, 13:33

[QUOTE/]Thanks for doing a serious aero analysis a la Mulsanne's Corner.

It's interesting to see all the different solutions being tried by the teams because of the current freedom in the rules![/QUOTE]

Thanks Ctesibios.

Regarding the efficiency of the Fiesta diffuser, I suppose it depends how you measure efficiency - if it is lift to drag ratio in isolation, then it might be, but if we measure efficiency as overall car lift to drag ratio, then at least to me it doesn't appear very efficient, but of course I haven't seen the numbers from their aero analysis. As you say time will tell who got it right.

Your question about allowed aero development through the year, I would be interested in the answer to this as well, though my suspicion and fear is that it will be close to none.

My personal preference of course would have been for much more freedom, but we all know how modern motorsport goes. Having said that, I think world rallying itself will benefit from a bit more aero (and other technical) development freedom as it will make people talk more about it, the past winter is a good example for this. You basically need to generate constant buzz around given subject if you wish people to pay interest to it on a more permanent basis.

**NickRally** · 22nd February 2017, 14:11

Guys,
After studying the 2017 WRC tech rules in more detail, there is one recurring theme, the reference to an additional document called homologation extension form 400/01 WRC, which either is not on FIA’s site or I am not skilful enough to find it. Is there anybody able to point me in the right direction for it, or is maybe already in possession of this form and is willing to share it?
Thanks,
Nick

**Mirek** · 22nd February 2017, 14:20

Hello Nick, normally the homologation extensions are not public. Maybe it is possible to ask them directly from FIA, I don't know, but for sure You can't find them on the internet (for any classes). I had them only once in my hand but those were initial ones for S2000 cars which means it's already eleven years old document.

**NickRally** · 22nd February 2017, 17:17

Thanks Mirek, to ask more specifically, let's take the diffuser rules - there is nothing in the tech regs saying what these are other than the reference to the homologation extension form 400/01 WRC, so for people like me coming from the world of circuit racing, it is unclear how the teams go about designing the diffusers if there is not a single point of tech reference that is the same for everyone. I appreciate all the base cars are different, but surely they all must be given some constraints, like how far back it can extend for example - where are these published?

**Mirek** · 22nd February 2017, 17:42

These details are probably part of the document we discussed before. Sadly it's not publicly available on the FIA website. I think that Your local ASN shall be able to provide the document to You. Maybe it's not for free. I really don't know as I have never tried to obtain one (the one I have I got for some work I did long time a go).