Mclaren Mercedes MP4-25

[TheMinister]

Yes, I'm pretty sure, because you can google the problem and will find more than 100 other studies about same effect. (blown flap, boundary layer control...) What I posted here is just I think the shortest, clearest explanation. You can find studies with 20-30 pages and more diagrams if you wish. The blowing wing concept is all about anti-stalling the wing : sticking the airflow to the surface of the wing all the way to the end. So the rear wing may "stall" in case of high angle,and high speed situation, but here the "stall" means dramatically increased drag+low downforce because the airflow is no longer sticking to the surface of the wing. It's my understanding though.

Aha, you were right all along; a bit of wikiing reveals this:
http://en.wikipedia.org/wiki/Circulation_control_wing

Seems to be a much better explanation of the concept- the blown flaps idea is something of an aviation-specific evolution on this theme.

This still leaves me puzzled as to why there was a line of the aero paint just above the slit (in those photos posted earlier). Does that indicate the airflow detaching from the wing, as Raptor suggested earlier? Surely that can't be the intention; or can it?

As to pup's idea with the pressure valvey doodah at the back; that sounds interesting, but is there any reason to stop blowing air out the CCW slit, at any speed? Would there be any possible drag reduction from stalling the wing at high speeds?(ie tune it so that when CCW airflow is stopped, wing stalls)

I guess that would basically be the same as my previous idea, only working the other way (so the blown slit is making the wing stall later rather than earlier).

Physics 101 just never prepared me for stuff such as that.

Heh, I feel the same. Trying to work it all out from badly written wiki articles and mentally modelling the airflow gives me a headache. Real interesting stuff though.

[tok-tokkie]

.......
Aha, you were right all along; a bit of wikiing reveals this:
http://en.wikipedia.org/wiki/Circulation_control_wing

Seems to be a much better explanation of the concept- the blown flaps idea is something of an aviation-specific evolution on this theme.

..........

Heh, I feel the same. Trying to work it all out from badly written wiki articles and mentally modelling the airflow gives me a headache. Real interesting stuff though.

I posted that same link on the 11th.

[TheMinister]

I posted that same link on the 11th.

And so the circle of thread life continues. Perhaps we should have some sort of wiki page that gets updated with the very best info on the cars to stop this from happening quite so much. Although if we did, then we'd quickly run out of things to argue about, and then what would this forum be....?

[Pup]

There is only one rule for discussing the Wing of Circular Debate™, which is that no one is allowed to say or post anything that wasn't mentioned here on Feb. 1.

We'll give Kalinka a pass, since he's new.

[kalinka]

Pup, I think the linked paper concludes just what I think it might be good for an F1 wing design : It concludes that with blow-wing design you can actually go with higher wing angles without losing the sticking airflow, and all that at low speed ( wich again might be even high speed in F1 , because the paper is for airplanes ). Not to mention the other important thing the paper says : all this significant lift/downforce is achieved without increasing drag !
This system is significant on airplanes only at liftoff/landing where additional lift is needed beacause of low speed ( but you must consider that airplane takes of / lands over 180-200kmh maybe more ). So this effect might work in F1 at normal speed/high speed cornering ). Maybe it has an advantage only on high downforce tracks, but surely does not have any disadvantage at high speed tracks. It says that as the speed increases, the effect is becoming smaller. On high speed tracks you can even block the air intake to "switch off" the blown wing.
Please correct me if I'm wrong. Before 2 months i dont have a clue about this , but since I'm spending lot of time researching over the internet.

Pup, thank you for forgiveness. I read almost the entire 80+ pages before I begin posting, so I'm sorry, obviously I skipped some pages. But if you mean the wikipedia link, I never posted any wiki link as best I can remember.

[firbanks]

Hi, I am new here, but have been following this discussion with great interest. I have a question that I am hoping someone more knowlegeable can comment on. If the slot in the wing is intended to reduce flow separation in the same way as the BMW wing of last year, then what advantage is conferred by routing air though the shark fin as opposed to having the slot on the leading edge of the wing as seen last year? Would it simply be a matter of increased intake volume?

[Confused_Andy]

I guess by routing it via the sharkfin they can also use it for a small amount of cooling, things could be mounted higher up to reach the bottom of this colder tunnel inside of the bodywork.

That would be my guess, combined with the greater intake of air the inlet would provide.

[SLC]

I guess I'll just say it again:

The slot is for being able to, on command, stall the top rear wing.

The reason for using an elaborate ducting system through the roll hoop and engine cover is to add the ability to control the flow such that the stall can be induced when desired.

[jason.parker.86]

I have been following this with great interest; but can anyone explain the rear wing setup in simple terms? I got lost on page 2

[firbanks]

I guess I'll just say it again:

The slot is for being able to, on command, stall the top rear wing.

The reason for using an elaborate ducting system through the roll hoop and engine cover is to add the ability to control the flow such that the stall can be induced when desired.

This is one theory, but I have not seen any hard evidence to support it yet. However, you understand what I am getting at: if there is no clear advantage to routing air through the sharkfin to a blown slot that otherwise functions in the same way as last year's BMW, then why have this configuration.

[cupidstunt]

I guess I'll just say it again:

The slot is for being able to, on command, stall the top rear wing.

The reason for using an elaborate ducting system through the roll hoop and engine cover is to add the ability to control the flow such that the stall can be induced when desired.

Please explain why you would want to stall the rear wing? So far as I can work out all this would do is reduce downforce, but wouldn't reduce drag (which is what I assume you're getting at). Correct me if I'm wrong.

Also, surely any big reduction in rear downforce at high speed would produce a very unstable car.

Also also... "on command"? without a movable aerodynamic device? Explain how?

[Raptor22]

He can't explain to you or any of us in any great detail what the benefit of a stalled rear wing is.
Any stalled wing has the aerodynamics of a brick (that's why stalled wings don't fly) and also the drag of a brick, (which is why they don't fall as fast as say,....bombs)

The routing via the engine cover is not known yet. We have postulated how they may achieve a more marked pressure rise through this packaging but nothing is concluded because non of us has looked under the engine cover yet.
It is certainly not conclusive that the rear wing blowing mechanism is being fed via the roll hoop inlet either. That's just an assumption that's been used to the point where it is almost becoming fact (not truth)

it is highly plausible that they could be using:

- Side pod air to feed the rear wing
- roll hoop inlet air
- recirculated exhaust gas after cooling via an intercooler
- a few other fantasy ideas

the truth is we just don't know at this point.

What is truth, is that they are not stalling the rear wing, the flow vis images shows this clearly.

[cupidstunt]

Any stalled wing has the aerodynamics of a brick

That's what I suspected, thanks. Very concisely summarised.

Appologies if i've missed this and it's been discussed before, but would there be an advantage in feeding the wing with warm, high energy air, heated by perhaps the oil radiator.... hence the advantage of routing via the engine cover?

[Pup]

Pup, thank you for forgiveness. I read almost the entire 80+ pages before I begin posting, so I'm sorry, obviously I skipped some pages. But if you mean the wikipedia link, I never posted any wiki link as best I can remember.

No, my joke was that you're one of the few who've posted some new info for us. I'm glad you did, and welcome to the forum.

[Pup]

Any stalled wing has the aerodynamics of a brick

That's what I suspected, thanks. Very concisely summarised.

Appologies if i've missed this and it's been discussed before, but would there be an advantage in feeding the wing with warm, high energy air, heated by perhaps the oil radiator.... hence the advantage of routing via the engine cover?

I think your first instinct was right - that they're just able to get more air from the intake than a scoop. I don't think it's any more complicated than that.

I really, really think this is just an extension of the scoop concept from last year, and little more. I think we're all overanalyzing it a bit.