Reducing the drag of a two element wing through stall

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horse
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Joined: 23 Oct 2009, 17:53
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Re: Reducing the drag of a two element wing through stall

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ringo wrote:we truly don't know what phenomena is causing this.
I think we have a few potential theories ringo and, a bit like the drivers, there are advocates for each and every one. The way I see it there are two main classes, with a couple of different techniques for each. These are:

1/ F-duct is fed air in the straights:

In this case, I think there are two jobs to do here:

a) The wing must stop generating lift which in turn has a high level of induced drag from the steep AoA of the flap element. You could do this by equalising the tangential velocity of the flap element, so that it generates no vortex sheet and thus no upwash.

b) The form drag of the wing must also be dealt with by feeding air into the low pressure zone behind the wing.

I guess achieving a) and b) are somewhat complimentary, but I like to think of them as separate tasks.

2/ F-duct is fed air in the corners:

This is the more simple approach where the wing is simply a blown flap. The air is fed to the wing in corners to improve the downforce of the wing. In theory, you can then run a less aggressive AoA than required without the blown flap.

Looking at the level of wing on the McLaren cars, particularly at Monza, I think this approach 2/ is less likely to be the correct one, but who knows?
marcush wrote:wich is worth .2kph top speed.. :lol: :lol: maybe thats the case.
Yeah, I guess it seems unlikely, but Mercedes have been doing some weird things this season. Maybe the suggestion of using the flow to stall the diffuser (as in feeding some air into it) is not so far off the mark. I guess the Merc's pipe work must go nearby if it goes up the wing end plates.
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forty-two
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Joined: 01 Mar 2010, 21:07

Re: Reducing the drag of a two element wing through stall

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Continued from the STR thread:
lolzi wrote:
forty-two wrote:Yes, that is a very good point Paul.

I actually have a theory that the device on the McLaren might actually somehow still be present next season because of the way in which theirs and I believe theirs alone has been implemented.
Could you elaborate? What do you think they are doing differently?
imightbewrong wrote: Can you elaborate on that?
Just a little theory of mine, but I have noticed so far that:
- McLaren drivers have normally not been seen "operating" their F-Duct, with the exception of one or two practice sessions.
- There has been speculation by many that the McLaren system has a "hole" within the tub (out of view) which the drivers block with their "left knee", but I have not seen ANY evidence of this.
- As a few contributors to this particular thread have speculated, the McLaren system could very well be an "automatic" or rather "tuned" system which operates automatically at the correct speeds WITHOUT the need for any driver intervention.
- The above point, IMO makes the McLaren system fundamentally different to every other team's implementation of the system (with the possible exception of Mercedes).

All of the above suggests to me that IF a ban on the "F-Duct" were to be introduced for 2011, there is a chance that whatever the wording of the "ban" were to be, there is a possibility that it might NOT prevent McLaren (and possibly Mercedes) from being able to continue to run theirs.

Since the "BAN" has not been published (to my knowledge), the final part of this is purely speculative.
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wesley123
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Re: Reducing the drag of a two element wing through stall

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I woulkd rather think it is tuned to yaw, so the rear wing can even be stalled on really short straights between corners.
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forty-two
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Re: Reducing the drag of a two element wing through stall

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wesley123 wrote:I woulkd rather think it is tuned to yaw, so the rear wing can even be stalled on really short straights between corners.
Interesting thought.

Ringo did an animation some time ago (in cross section) which suggested that the tuning could work in a straight line, but that doesn't mean that it wouldnt/couldnt also be tuned to de-activate in the twisty stuff.
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doopie2you
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Joined: 26 Feb 2010, 13:42
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Re: Reducing the drag of a two element wing through stall

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I know the topic has stopped for a while but maybe this is usefull for the Dutch members! I made an article about it!

http://artikelen.foobie.nl/sport/hoe-we ... n-mclaren/
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