McLaren MP4/20 and those strange airbox horns

[Guest]

You may be looking at the airbox wing. The shelf wing, nearer the rear wing is definitely inclined.

Still your comment that it doesn't produce downforce addresses the central issue posed by reca, namely:

"I also don’t understand the comments about the “flow conditioner wings”, they modify flow direction but they don’t generate downforce by themselves... how is that possible"

[Reca]

My comment about the “strange understanding” sounded a bit harsh to some people and I’m sorry for that. My point is that reading some of the posts one gets the impression that an element is going to generate a force only if it has a 15+° angle of attack compared with the horizontal, the section has a very curved camberline and has endplates on both sides; if these requirements aren’t fulfilled then it doesn’t generate a force, you can’t even call that element wing or the section airfoil. Well, if all of that was true then many airplanes fly without wings. I was just trying to point out something that mep already tried to point out, with little success, not because his explanation wasn’t good but apparently because of the confidence of some posters on the opposite opinion, hence my comment about the “strange understanding”. I apologize if it sounded offensive, it certainly wasn’t my intention.

Well, I guess I am one of those who thought that that the "flow conditioner wings" direct the airflow towards the main downforce generating element, the rear wing and don't necessarily generate downforce on its own. They are somewhat like turning vanes that guide the airflow.

In fact also the turning vanes do generate a force on the supports. Any time you modify the flow direction with an element, you have a force on that element. Then, if to improve the airflow toward the main downforce generating element, I decide to put a wing to redirect the airflow, isn’t pretty natural that I try do to it in a way so the force generate by the element is also pointing downward ? If I succeed or not is matter of ability, wind tunnel time etc etc. so to comment each specific case isn’t easy, but the principle doesn’t negate it.
As for the shelf wings, it looks like they operate in collaboration with the rear wing, in a way that, especially in some designs, reminds me a bit of the leading edge flaps used on airplanes wings. Even if just judging by the inclination it looks like the shelf wing could generate lift, you have to consider the influence of the upwash caused on the element by the rear wing right behind and that’s pretty important.

youre wrong, those wings have no incline, they dont produce downforce nor lift, look closely at the first picture you linked.

You say that because the section is, judging from pictures, symmetrical, and horizontal. But as previously pointed out that doesn’t guarantee that the element doesn’t generate a force, you have to consider many things for the airflow direction, the mutual influence of the two winglets, the camera body right above, the fact that the winglets are on the upper edge of the engine cover, there’s the engine air intake right in front (and it has a huge influence in the airflow in that area with the amount of air entering in the intake dependant mainly by the engine rpm and not by velocity), the driver’s head etc etc etc. Furthermore for wings with a small aspect ratio (span/chord) 3D effects are pretty important hence the wing section tells only part of the story.
Obviously the resultant force isn’t going to be the 50% of the downforce of the car, but also assuming that it’s just a tiny percentage, I wouldn’t neglect that contribute considering that most of the game in F1 is on the small percentages. Then you have to work on the optimisation of the coupling with other car’s parts to achieve the highest efficiency, but the same is true for every part of the car, basically no part of a F1 has only 1 function, everything is interrelated.

[walter]

how about turbulance? couldnt these be used to minimize turbulance? Or think of it this way, the air after the now downward sloping sidepods is also either dis-attached from the bodywork or has a downward stream close to the surface of the sidepod. ANY help is good for the rear wing, and directing the airflow so that it hits the rear wing at the exact angle is the key here. This improves the efficiency of the rear wings, which is more important than the extra drag that any of these little extra wings can generate. The game here this year is improving the efficiency of the downforce, since the rules were so detrimental to downforce.

[Guest]

In fact also the turning vanes do generate a force on the supports. Any time you modify the flow direction with an element, you have a force on that element.

From your earlier post one got the impression you meant a wing that modifies the flow direction always generates downforce. And you pointed out that the existence of a wing modifying flow direction and at the same time not generating any downforce, is impossible.
As you probably meant, and as you infact pointed out on this post I quoted, that a flow modifier wing always generates a force. A force not downforce exclusively.
This exactly was my point. I am not aware of a wing concept, aerofoil or not, that can generate a significant amount downforce in a vertical position. By significant I mean significant. You might even be able to accidentally generate some downforce by moving your hand through air, but I mean significant. So don't bother sticking to that with a witty(?) remark.

This, coupled with the fact that the Mclaren wing in question has a flat profile and no angle of attack visible by bare eye, I deducted that this is not a wing meant for generating downforce on it's own accord. Its a sensible conclusion I have come to by looking at the facts and adding 1+1=2. You are right, it's not as simple as saying a wing needs endplates to be able to generate downforce, but I am most certain a flat wing with close to zero angle of attack and in an upward inclining position is most unlikely a downforce generating element. I don't know where you got the idea I thought a downforce generating element requires specificly endplates, or camber, or an angle of attack. I'm quite certain that remark was aimed at me, even though some people got offended by it. [/i]

[bernard]

Oh, bugger. Damn autologin.
That was me, if you wish to reply, Reca. Which I'm sure you will.

[mep]

I think a few points get lost. So I try to explain them again.

First of all the span of the wing is limited by the regulations.
That's the reason for the vertikal elements. For those wo don't know what vertikal is (vertikal like this I )
They look and maybe work like airplane winglets, so let us call them winglets.
Visit this side to get some knowledge about winglets.
http://www.mh-aerotools.de/airfoils/index.htm
In short they increase the span a little bit especialy if it's limited like in our case.

Seconly the horizontal (horizontal is this ----- )element. I still belive
it's in a very good position to generate downforce. It is in cleaner air than the rear wing because no part is in front of it.
Indeed it hase no sicnificant angle of attack but this is not necesary as I have explained in an ealier post. The profile of the wing is important, and I can't see the exact profile so I want to know how bernard can say it does not have one? Please send a picture ,where the profile is visible exactly.

The small angle of attack is very good because the most downforce is produced by the less drag. It's the reason wy airplanes don't fly with an high angle of attack.

Another reason for the low angle of attack is the rear wing. With an high angle of attack the air would be guided over the rear wing and it would lost it's efficenty.

[mep]

The other theory is that those horns guide the air down to the rear wing and so increase its angle of attack indirectly. I think this could be posible especialy because there is a guerney visible in this area and it's an indicator of high angles of attack. But if it guides the air down, it would need a positive angle of atack (wich I can't see) and therefore would produce lift.
The produced lift is maybe as big as the extra downforce by the rear wing so the sum is zero + the additional drag produced by the horns and the rear wing which has now a higher angle of attack. So I think this is not an advantage and therefore a wrong theory.

English is not my mothers language so my explanations can be hard to understand.

[bernard]

I am not saying that it couldn't be there to produce downforce.
I would be happy to admit I'm wrong.
the facts I have are:
I BELIEVE the profile is very flat. Haven't seen the actual car. The shape is naturally aerofoil, but a very flat one at that.
I can't see any angle of attack.
The wing is positioned, yes, vertically, with part of it even in an upright position.
Based on those "facts" I'd be willing to rather believe the theory of a wing aiding the rearwing.
But it could be either way. My facts are pretty limited and uncertain.

[Reca]

Bernard :

the impression that a wing needs endplate to be called wing didn’t come from your posts, but from ZE.FT. post :

To name this device as a wing it must have a camber plus endplates which seperate vortices on top and on the bottom of the wing ends. If an aero device has no angle of attack and I cant see any angle of attack plus the plates at the end cover only the high pressure zone on top there then it is not a wing to create downforce.

The comments looking strange in your posts were :

Yes, it is, but that doesn't look like a downforce element either. Firstly I think it wouldn't be bent upwards (like this / ) and most importantly it's not an aerofoil.

Now you explained again your thoughts about the section not being an airfoil and I do understand a bit more what you mean but still I’ve to say that it’s not conclusive. And it still sound strange to me the comment that the main part having a dihedral of roughly 20° (that IMO is more because of refuelling than because of aero) exclude that it’s to generate downforce. You say you aren’t aware of vertical wings generating downforce, but that one isn’t vertical, only the tip is.

That’s why, to me, both your comments, some of the ZE.FT. comments, and a few more from other posters did sound strange and that’s what I said, or at least I tried to say, I see that probably I did choose the wrong words to say it. I preferred not to quote each exact comment before simply because it was a general impression given by different posts from different people.

I don’t know exactly what the “horns” are for, downforce ? lift ? guide the airflow ? I don’t know. As I already said I’ve a few different ideas, most of them I would have difficulties to explain in detail with my bad English and without drawings, especially because I also have an equal number of doubts about each of them. So, without actual data, I’m open to any possibility.
What I know for now is just that the justifications used to show why the device isn’t to generate downforce, although to you probably look like a straightforward 1 + 1 = 2, don’t look equally simple or conclusive to me, and that’s probably because I know that quite often in aerodynamics 1 + 1 isn’t 2.
It’s just that. No intention to attack, prove people wrong or anything else.

[bernard]

I looked at the in car camera during this quali, and the horizontal part of the wing is actually producing lift.
Looking at other pictures, the vertical parts are cambered to the inside. With a small flap.
My most recent assesment would be that the wing guides in air from the sides towards the middle of the rearwing, and the horizontal parts pull air that would gove above to lower towards the rearwing.
You get more air to the rearwing, making it more effective.
i believe this is the real reason behind the original airbox wings too. They are not there to make the flow more laminar, but to pull air from above - down towards the rearwing elements.
I'll try to whip something together in fluent to explain a little better, but I'm not making any promises - 3d modelling and meshing/ analyzing is a bitch. Currently I can handle only 2d decently.

Mep asked for pictures:

here is an example:
http://www.formula-one.net/pics05/velke/20-03-18b.jpg

The picture is from:
http://www.formula-one.net hundreds of extremely high quality pic ... eams. :(

[mep]

Ok, on that picture you can guess the profile of the vertical element.
I would say at the tip of the vertical element the profile is fully symetrical (upside equal to downside). And the tip has a very tin profile.
But this is quite naturaly for winglets on airplanes.
The profile at the tip is other than in the middle of the wing.

Importand is the profile and the angle of attack of the horizontal element.
And this is hard or maybe imposible to see.
But if you look from the front I would say the profile of the horizontal element is not so flat. Especially compared with the rear wing.
producing lift or downforce.
In motorsport are several reasons for using very tin profiles compared with airplanes.

Parts who only guide the air like bargeboards in general don't have any profile.

[Alex4]

Maybe I didn't read carefully enough but nobody seems to mention this option of these "winglets" on MP4/20:

It's about airflow in vertical plane during turning.
In the turning inside to the curve the part of the rear wing is aerodynamical shadow cast by airbox (even more with the longer airbox).
The outer one of winglets is out of the shadow and is able to direct normally wasted airflow to the rear wing element.
The inside part could have effect of guiding airflow over part of rear wing which is inside the curve (with bit of roll stabilising effect).

While car is moving straight I don't believe that the vertical parts of the winglets play any role, because they are too high to affect flow caused by helmet and they are too forward to affect turbulencies around airbox intake. (too wide too)

[Art]

I think they help to direct the flow back down to the rear wing. remember the front wing will directed alot of air upwards that would go go clean over the sidpods and may even miss the rear wing(or reduce its effective angle of attack). even more so now with the new front wing regs if u look at a side view the front wing are very high!. In light of this flow from the front wing these horn things would see an effective postive angle of attack due to this upward moving flow from the front wing.

Looking further into this concept if u look at a front view of the car the horn things are right infront of the rear wing so if they were to produce downforce they would do a very good job of deflecting the flow up and over the whole rear wing! reducing the rear wings angle of attack and creating alot of turbent flow for it.

[RH1300S]

Maybe I didn't read carefully enough but nobody seems to mention this option of these "winglets" on MP4/20:

It's about airflow in vertical plane during turning.
In the turning inside to the curve the part of the rear wing is aerodynamical shadow cast by airbox (even more with the longer airbox).
The outer one of winglets is out of the shadow and is able to direct normally wasted airflow to the rear wing element.
The inside part could have effect of guiding airflow over part of rear wing which is inside the curve (with bit of roll stabilising effect).

While car is moving straight I don't believe that the vertical parts of the winglets play any role, because they are too high to affect flow caused by helmet and they are too forward to affect turbulencies around airbox intake. (too wide too)

To help me understand this, can someone clarify how the air-flow approaches the car when it is turning?

I envisage that if the car is not yawing (oversteer) - then it is still effectively approaching the air flow head on - after all the car is moving through the air, not the air moving past the car (assuming no wind).

These horns look like they would be there to clean up the flow to the rear wing - surely the horns would help control vortices coming off the tips of the air-box winglets.

[West]

Picture a streamline cutting a diagonal, longitudinally across the car. That's what is consider air flow in a yaw condition. The RaceTech Magazine w/ the Sauber front cover (maybe 2 issues ago?) shows a picture of it in its article.