Technical Analysis: WRC Cars 2017

[itix]

Those fluent in the technical rally car knowhow, does the modern rally cars have some kind of guard or protection for a flywheel blowing out or coming loose?

Having been unfortunate enough to have seen the aftermath of a flywheel going on a trip on a former colleges (he is alive and well, the engine was mounted longitudinally) dragrace car I know the consequences it can have.

[Fast Eddie WRC]

Anyone know why the MSport rear spoiler might have broken off ? Poland was the second time one has done this on the '17 car and it cost Tanak the win IMO...

[noel157]

Anyone know why the MSport rear spoiler might have broken off ? Poland was the second time one has done this on the '17 car and it cost Tanak the win IMO...

Who else has had it happen?

[AnttiL]

Who else has had it happen?

Østberg in Sweden.

[mmm]

Who else has had it happen?

Ostberg in Sweden.

Anyways they have some serious miss-calculations when designing the parts. The diffusors broke off in a similar way - the area right around the bolts is too weak.

[NickRally]

Citroen keep persevering with their "nice" lift creating mud flaps in front of the rear wheels, only team to do so, I find this very peculiar:



Compare this to Ford:



Not to mention Toyota and Hyundai who have gone a step further and designed some nice little venturis in this region.

[mknight]

What I found strange is how "soft" the guiding vanes in the diffuser on some of the cars are. In quite a lot of jumps you seem them flapping around wildy. (Citroens and Toyotas at least)

Yes if they are too rigid they will break off easily when car touches the ground, but if they are too soft they won't really help in keeping laminar flow. Maybe they flap only during the jump and not when actually doing the work close to the road?

[Mrpengski]

Nick, supposedly the flaps forward of wheels have some masking effect and can reduce the pressure if done right. Sorta like the rear wheel scraper certain F1 runs I guess

We tested both rigid and flappy diffuser fins during development. Everyone was expecting the fins to disappear very quickly, but turned out that they were not really getting damaged, if at all, under normal use. In the end, it was better to risk losing the bottom 10mm of rigid fins, than to have flappy fins destroying all the flow through the diffuser.

[NickRally]

Thanks for the insight Mrpengski, this is really appreciated - you are quite right, there was so much discussion about the damage all these fins will suffer and yet it is not really happening.

On the forward facing flaps, aren't the ones we use still on the top surface . Actually this reminds of a story I read long time ago about the time when Dan Gurney started using little trim tabs on the rear wing (which are now known as gurneys) and the fact that he tried to hide their real purpose by saying they are to stiffen the wing, so another team copied him, but placed the tabs on the underside supposedly to not increase the air resistance of the wing...

[Revman]

Quick newbie questions.....

1) Is the intake on the roof for driver ventilation?
2) Does the driver consult with an engineer prior to shock tuning between stages?
3) Is there a development freeze on chassis, body, and/or engine to contain costs? I think I heard three years. What can the teams do during that time in terms of development?
4) These cars costs $900,000 US compared to a NASCAR at $250,000 US. NASCAR struggles for sponsorships and TV packages to keep teams alive. How does the WRC do it?...Maybe not a purely technological questions, but indirectly related.

Thank you