Front splitter end plates

[Mr168]

In looking at some of the most successful hill climb and time attack vehicles, those running substantial front splitters as part of their aero package frequently have very large end/spill plates on them. Key examples would be the Peugeot T16 at this year's Pike's Peak, and several variations of those driven by Tajima also at Pike's Peak.

Can anyone here enlighten me as to the function and benefits of these massive end plates, and how the advantages may outweigh the resultant drag?

 

[KENAT]

Wikipedia gives a starter for 10.

https://en.wikipedia.org/wiki/Wingtip_device

I seem to recall even a fairly elementary text like Barnard & Philpott gives some explanation on the various forms of wing tip devices.

http://books.google.com/books/about/Aircraft_Flight.html?id=kAoHD51GkSoC

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[Mr168]

Kenat - I was under the impression that because the end plates are not in free air on these cars, that much of those characteristics don't apply. The styles that I'm referring to, are actually sealed to the front fascia/fenders.

 

[KENAT]

I'd still think it had some effect on spanwise flow of the air/flow of high pressure air under the wing around the tips onto the top of the wing.

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[Mr168]

But why not vertical plates that aren't sealed against the fender/fascia? One would think that would result in considerably lower drag. Is it simply a means of creating as large a high pressure zone as possible?

 

[IRstuff]

I don't see how the vertical plates help with drag. The net effect has to be that the effective cross-section is increased, since the air that impinges between the center of the hood and the plate cannot go sideways and must deflect upwards, which is a longer path.

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[KENAT]

Sorry, I didn't read your post closely enough and was looking at the rear wing.

At the front I see what you mean about it sealing to the sides now. In this case you're going to get a 'bubble' of air to some extent. I suspect you'll get some down force from diverting airflow but it may also act like a more 'pointed nose' - a bit like the bubble in the back of a pick up can act like a teardrop back. May even help force more air through that central grill If I'm understanding the layout properly.

Is this a way of gaming the rules of the race? Is there a limit to length of nose or similar but aerodynamic wings are allowed beyond this? Or perhaps changes to the stock vehicle are limited or some such?

Many aerodynamic features of race cars aren't strictly the 'best aerodynamic shape' but an attempt to get the most out of imposed regulations - be it class regulations for true race cars or various crash safety rules for road cars. Both NASCAR & F1 certainly take this approach.

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[Mr168]

Kenat - no rules in this instance, as they run in the unlimited class, and have no restrictions on the aero package. The one pictured above was selected from scratch as the design by the Peugeot factory team, and absolutely slaughtered the record on a tarmac surface. Previous record holder on a mixed surface also had the large spill plates, but on an even more pronounced splitter. The design works, I'm simply trying to understand the why and how!