Mclaren Mercedes MP4-25

[horse]

I think it was a hole originally, just like Ferrari and Toyota's.

But then one day it disappeared...



Alien abduction?

Oh yeah! I never picked up on that last season. Did anyone else? Is this just the same system applied to both elements and fed from the airbox scoop?

=D> by the way.

[Shaddock]

I think it was a hole originally, just like Ferrari and Toyota's.

But then one day it disappeared...



Alien abduction?

Oh yeah! I never picked up on that last season. Did anyone else? Is this just the same system applied to both elements and fed from the airbox scoop?

=D> by the way.

Wasn't the slot only used on high downforce configs? Medium to low DF there was no need to run with one.

[Pup]

Wasn't the slot only used on high downforce configs? Medium to low DF there was no need to run with one.

Yes, but see the earlier post. They ran the scoop in Suzuka, but while there's an inlet, there's no visible outlet; whereas before, when they ran the scoop, there was an obvious outlet slot visible from behind.

The pics are a bit confusing, since they are out of order. In Singapore, they had a scoop with a visible slot in back; in Brazil, no scoop, no slot; but then in Japan, a scoop but no slot.

[biggles22]

There's a difference, though. Look at the Suzuka pictures from last year - the 24 had a scoop, but no obvious outlet. Is there not the faintest outline of a slot on the bottom element here, or am I seeing things?

I think that slot is identical to Ferrari's. Just seems to be a hole in the main plain.

http://www.formula1.com/news/technical/ ... 0/662.html

F1 technical described it as a "Third element"

http://www.f1technical.net/development/246

Seems like this solution can only be used for a short section. Perhaps because it is not visible from the front the blown flap can be used for the whole wing?

EDIT: I don't know, you might be right though, Pup, I can't find a good picture of the outlet for last years McLaren wing, just the inlet.

The centre scoop from last year was limited by the rule that governs appendages on the car, you can have appendages/scoops/flaps/vanes between 75mm of each side of the centre line, so it was limited to 150mm wide. McLaren's new idea probably uses a hollow section in the upper wing plane, which doesn't count as an aero appendage because it is inside the wing. That's my take on it anyway.

I'd agree with the idea that the slot is feed/controlled passively, having it mechanically/electrically controlled would be too heavy/confusing (would the standard ecu be able to even encorporate this?) Aslong as the intake is the correct size it will feed just enough air to stop delamination at the right time.

[mike_dangerous]

i'm really confused with all this suction stuff etc. with the rear wing

please can some1 explain it simply for me what the theory is?

Thanks and sorry for sounding dumb

Not dumb, perfectly valid question.

So, a wing has, in general, a long curved upper surface and a shorter lower surface (you also get symmetric profiles that are the same top and bottom, but don't worry about that for the mo).

Essentially, packets of fluid that are in contact at the front or leading edge of the wing will be in contact at the back or trailing edge. For this to happen, the flow over the top must travel faster than the flow over the bottom as the top surface is longer.

This difference in speed generates a low pressure on the top (suction side) and a high pressure on the bottom (pressure side). This difference in pressure causes the wing to generate lift. Reverse it for a F1 car and you get DF.

Now, the steeper the angle you place your wing relative to the oncoming flow, the higher your lift will be (and drag normally), until at a certain angle the flow attached to the suction side of the wing can no longer hold on and separates. This process simply produces more drag for no extra lift.

If high velocity flow can be injected into the flow on the suction side in the direction tangent to it, then this separation can be delayed with excellent lift benefits (a bit like having an extra wing).

What is odd is that (as far as I can tell) all blown flaps are normally driven by a pump (normally an aircraft engine), yet these F1 versions would be seem to be passive. This is what concerns me about sharing the engine snorkel as the deficit for using the flow from there to blow the slot is likely to manifest itself here as some sort of back pressure. I should imagine it's quite a delicate system which is maybe why the slot size has changed.

Anyway, that's my ten pence worth. Hope that explains the semantics a little better.

EDIT: (for grammar)

Hi people, I've been following this thread for quite some time as I am a McLaren fan and wanted to see what others thought of their new car (and also the others, especially with such an exciting season ahead).

Anyway, I read your post Horse and thought I would try and put you right. The idea that a wing generates lift because as you put it "air packets" meet at the front and back is flawed. In reality air flow must follow the surface of the wing and to do so must follow a curved path so a force acts to change its direction resulting in a change in velocity. This change in velocity caused by the force acting on the air is what causes a lower pressure on one side of the wing and depending on the incidence and/or the profile of the wing, a higher pressure on the other. It is NOT because the air has to be in contact with each other at the front and back but that it has to be in contact with the wing. When things become supersonic though things become very different I would have thought so its a good job they put a hold on engine development

[Pup]

On the other hand, I may be completely wrong, since here's a picture of Lewis at Suzuka, and there's clearly a slot in the back.



They could have been running two different wings, and the pics from below are of the front of Hamilton's wing, but the rear of Heikki's; or perhaps the pics are from different days. That does look like Lewis' hemet in the previous rear end pic too.

[ringo]

I still have a hunch they want to reduce down-force and not increase it any further.
Rear wings are only 30% of the total down-force. If it was blowing to replicate a 3 element, that slit might only have a slight improvement since it is not a true 3 element wing.
3 element wings have 3 suction peaks, this thing will only have 2, the second peak being "plateaued" or elongated by the flow through the slit.

A 3 element would also allow them to run steeper angles of attack and higher cambered wings. Hard to tell from here the difference between the 2009 and 2010 angles and camber.

I have a question, are fans illegal for radiators alone and can they be used for other cooling needs?
A blown flap, will require increased blowing for increased air speed. The air passing through that slit will have to be many times faster than the free stream air velocity, and faster than that under the wing. Blown flaps are used at landing speeds, which don't require as much blowing power.

This thing Mclaren has, if it is a blown flap, may be designed for low speed turns, ie when the blowing is higher than air speed under the wing. I think the redirected free stream air will provide the required blowing at such low speeds. Above that i don't know if it will work.

This is why i kinda like to the crazier idea of reducing the down-force on the wing, not stalling it, but making it so that it behaves like a 1 element wing (or one of those tiny wings they use at monza) at high speeds and behaves normally in the turns at lower speeds.

borrowing bar555 picks for a moment!

It could be possible to have a wing behave like it wasn't there (without stalling it, stalling is never good) by having equall pressures on both sides??

[Raptor22]

If you look at the image showing the vis flow on the right you'll see that the dye shows up exactly the wavy black line on the rear of the wing. If there is air being fed through the fin to the rear wing it's along this line that I'd expect it to be coming out. What do people think?

If that slot is pumping air, the flow rate must be tiny! Considering the size of the auxiliary inlet, the back pressures must be huge (would this maybe stall the flow into the airbox???). This could, of course, explain why the inlet size has been reduced.

Still, I think the flow viz had simply got stuck on the ridge through some circulation and the picture on the right would make me think the slot is not blowing at all or it would have blown the flow viz paint off. The picture on the left could show the slot blowing, but it's a bit inconclusive.

tiny flow rate or not, when I experimented with flap bloing in my aerospace days a little pressure went a long way. Its merely to do with keeping the boundary layer flowing over the wing but that flwo speeds up quickly as the air it is introduced is at a much lower pressure.

I doubt the flow into the airbox will stall and even if it does it makes no difference anyway since the airbox creates a massive expansio which raises the pressure and drops the velocity of flow so the engine can breathe pressurised air.

If the flap is fed bypass air, the positive pressure at the inlet and the lower air pressure behind the wing will keep the flow moving.

[horse]

Anyway, I read your post Horse and thought I would try and put you right. The idea that a wing generates lift because as you put it "air packets" meet at the front and back is flawed. In reality air flow must follow the surface of the wing and to do so must follow a curved path so a force acts to change its direction resulting in a change in velocity. This change in velocity caused by the force acting on the air is what causes a lower pressure on one side of the wing and depending on the incidence and/or the profile of the wing, a higher pressure on the other. It is NOT because the air has to be in contact with each other at the front and back but that it has to be in contact with the wing. When things become supersonic though things become very different I would have thought so its a good job they put a hold on engine development

EDIT: (Deleted stupid rant) I think this wikipedia article provides the best explanation of what's really going on. Circulation, circulation circulation!

http://en.wikipedia.org/wiki/Lift_(forc ... ished_flow

tiny flow rate or not, when I experimented with flap bloing in my aerospace days a little pressure went a long way. Its merely to do with keeping the boundary layer flowing over the wing but that flwo speeds up quickly as the air it is introduced is at a much lower pressure.

I doubt the flow into the airbox will stall and even if it does it makes no difference anyway since the airbox creates a massive expansio which raises the pressure and drops the velocity of flow so the engine can breathe pressurised air.

If the flap is fed bypass air, the positive pressure at the inlet and the lower air pressure behind the wing will keep the flow moving.

Thanks Raptor, that answers a lot of my questions.

[Shaddock]

I have a question, are fans illegal for radiators alone and can they be used for other cooling needs?

Illegal Full Stop, although Murray always claims that his fan car wasn't banned, but Bernie pressured him to drop the design.

[mike_dangerous]

EDIT: (Deleted rant)

I don't know what you wrote but I was definitely not trying to undermine you or be rude. But looking at that Wikipedia article the use of the words constriction suggest that lift is produced in an effect similar to that of a venturi nozzle, or I may have misunderstood. However that method is also wrong:

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong3.html

I thinks this is the best explanation of what I was trying to explain in my previous post and is the right method for producing lift:

http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html

Anyway it is pointless to get into an argument over such a thing and I'm sure McLaren know the correct theory for the production of lift on a wing and subsequently exploit it in their design.

Edit: After seeing your edit to your original post you seem to have changed it to something which I think is the same as what I was getting at only worded in a different way and again different to the wikipedia article. Sorry I digressed from the real subject matter here...

[horse]

I don't know what you wrote but I was definitely not trying to undermine you or be rude. But looking at that Wikipedia article the use of the words constriction suggest that lift is produced in an effect similar to that of a venturi nozzle, or I may have misunderstood. However that method is also wrong:

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong3.html

I thinks this is the best explanation of what I was trying to explain in my previous post and is the right method for producing lift:

http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html

Anyway it is pointless to get into an argument over such a thing and I'm sure McLaren know the correct theory for the production of lift on a wing and subsequently exploit it in their design.

Edit: After seeing your edit to your original post you seem to have changed it to something which I think is the same as what I was getting at only worded in a different way and again different to the wikipedia article. Sorry I digressed from the real subject matter here...

Urg, wrong twice! The shame. The problem for me is that I understand it in such an abstract way (see my edit to the original post) that I'm obviously not so good at explaining it physically. This comes from working for 5 years with panel methods which has turned my brain to putty. I don't think the stream tube argument is quite the same as the venturi argument as it does consider the flow above and below the aerofoil as well as the stagnation points. I could be wrong, I hope no one ever asks me to teach this. Anyway, I don't like velocity, just velocity potential.



EDIT: And sorry Mike, I did overreact to your first post. My bad.

[Confused_Andy]

Im not sure the "snorkel" is a inlet anymore, the hole it in looks like its not a hole rather a cover for perhaps another sensor?

It has a shein on it like you get with IR sensors, just dunno what it'll be sensing up there.

[kalinka]

Hi all Mclaren fans !

This is my first post. I was following this forum since the start of the 2010 testings. I am following F1 since 1989. Some explanation I found for blown flaps :

http://www.aerolab.com/Display_Pages/Flow_Vis.html

At the bottom of the page there is an example of not blown/blown pair of wings, and visible airflow around them. It's clearly visible that a blowned wing has a great advantage in retaining the flow much longer around the wing.
Hope I helped. I think too, that it has to be something special with this Mclaren rear wing.

[deus1066]

Welcome to the forum. I too was a long time lurker before joining.