Mercedes AMG F1 W05

[Morteza]

I could spot these parts being the old versions:

[OO7]

Side pods and engine cover are of the launch specification and the roll hoop doesn't feature the lateral cooling ducts.

[turbof1]

Halfway season Front wing evolution/analysis - warning: epicness incoming:
http://www.f1technical.net/features/19448

[trinidefender]

Halfway season Front wing evolution/analysis - warning: epicness incoming:
http://www.f1technical.net/features/19448

http://f1tcdn.net/images/features/2014/ ... sfw2.0.jpg

I have a few issues to bring up here with your analysis of Mercedes front wing evolution. If you have an issue with anything I am saying please tell me.

1. "The gap bled off high pressure from the wing elements, preventing airflow separation and stalling." The high pressure side of a wing is never the side at risk of stalling. That would be the low pressure side. To prove my point look at the front and rear wing. The high pressure side of a wing always bleeds off into the low pressure side PREVENTING the stall.

2. This is on the old wing. Did you notice that next to the centre slot on the endplate there is a wing element, the third element from the front. If you look at the vertical component of this element, I.e. Turning the airflow outwards, then you'll notice it is very long in relation to the elements before and after it. It is also right next to the slot on the endplate. I think the slot is there to work with this long vertical element on the front wing.

The first point was a fact, the second was my theory.

3. The flick that you talked about on one of the wings upper elements that you consulted Will Tyson about. He stated "The small flick created a tiny set of vortices to shape airflow around the front tyre." Let's analyse this, a vortex is formed by a pressure differential between two sides of an object or two or more surfaces. As it is, the vertical component where the flick mounts to curves outwards toward the endplate. This would create a vortex as the pressure gets higher on the side closer to the endplate and lower on the other side. Agree? Now, if you add that flick it actually creates a situation where the pressure gradients are evened off a bit as you move along the flick to the edge, this is a result of the flick being at a neutral angle of attack to the airflow. Therefore the flick would actually reduce the size of the vortex and reduce drag a bit off of that element. I personally think the flick is there so the vortex coming off of that vertical section (had the flick not been there) would interfere with the small turning vane next to it that was changed into a purely vertical turning vane.

4. "a wing producing more downforce without stalling at higher speeds." Do some reading on wings, increasing the speed through a multiple slot wing like this will not make it stall. Definitely not at the slow (relatively) speeds that F1 cars run. If you disagree with this statement then please I would love to see some references to material stating that this happens.

5. "Since the footplate doesn’t bend upwards in that region, it looks to keep airflow attached" again, why would the footplate bending upward in that region make it stall. High pressure sides of wings aren't the sides that stall. I don't know why they have the slots there, this has interested me as well and I want to do some research on it but I can almost assure you that the slots aren't there to reduce pressure on top the footplate to preventing it from stalling. My only guess would be to bleed pressure from the top of the footplate to encourage airflow to move into this area from the main wing elements.

6. "It’s to be noted that the base of tire creates a turbulent and very draggy vortex." The tyres do produce a lot or drag and create a lot of turbulent air but there is nothing to suggest that they create a vortex in the traditional sense. Airflow can be turbulent without a vortex being present.

7. "The second wing element has very little AoA, but due the placement of the strakes it still creates a fairly amount of downforce for only a very small drag penalty." The second element is also the largest in terms of area so you can bet that it produces quite a large amount of downforce. Also you cannot think of this wings in terms of individual elements as all the elements work together as one wing.

8. "Strake 4 is longitudinal straight, but latitudinal it has bent over its complete length. Important to know is that the strake is position right next to the inner edge of the tire. At the back end of the bent part of the strake, it creates a strong vortex at the tip, shielding airflow." Again, vortices are only created when there is a pressure differential. Strake No 4 is perfectly straight and aligned with the airflow under the wing. This means that the pressure is almost perfectly even between the left and right side of the strake which means no vortex. Also, that close to the ground, it is very hard to produce a vortex simply because of being that close. If you don't believe me then take a look at this, when a plane comes into land it encounters what is known as ground effect. Ground effect affects wings up to about a wingspan away from the ground. When the wing reaches about this distances the wing becomes much more efficient as a result of ground effect. One of the causes of this is the reduction in wing tip vortices. Why is it not possible that strake No 4 could simply be there to keep the airflow laminar and keep the airflow straight going to the inside of the tyre.

9. "they create a vortex right above the strakes. Air between the strakes and the underside of the wing tends to stagnate, which creates drag. Creating a vortex in front of the stagnated air re-energizes the air there and speeds it up." Yes the overt generators there do push a small vortex through the slot gap of the wing but one minor point. Air on the underside of the wing (the low pressure side) does not stagnate. It actually speeds up in airflow, it is this acceleration in airflow that creates a low pressure and hence the pressure differential between the top and bottom of the wing and therefore the downforce on the wing. The slot gaps are there to stop the airflow from separating and becoming turbulent by feeding more air into the low pressure side. Yes as you can imagine this decreases downforce. It also allows you to run a much higher angle of attack which increases downforce more than the loss from the slot gap. That trade off is a drag increase which F1 designers are happy to live with. The vortex generators are another method to keep airflow attached to the bottom of the wing.

[turbof1]

Trindefender, you made some good comments on it. Indeed after a good night of rest, something I lacked the last few nights, I also see the points where I went wrong. HOWEVER, not everything you tried to adress was wrong, in in some cases you were picky. I'll mention where.

Alright, let's get on it.

1. "The gap bled off high pressure from the wing elements, preventing airflow separation and stalling." The high pressure side of a wing is never the side at risk of stalling. That would be the low pressure side. To prove my point look at the front and rear wing. The high pressure side of a wing always bleeds off into the low pressure side PREVENTING the stall.

as you said, this is fact and indeed I was incorrect here. However, the gap inbetween the endplate does have the function of bleeding off high pressure airflow. Now the question is why. After giving it some more thought it is to decrease drag.

I think you can very well compare this to the rear wing. They run multiple louvres to bleed off high pressure airflow in order to create less drag. It does come at the price of a bit less downforce.

2. This is on the old wing. Did you notice that next to the centre slot on the endplate there is a wing element, the third element from the front. If you look at the vertical component of this element, I.e. Turning the airflow outwards, then you'll notice it is very long in relation to the elements before and after it. It is also right next to the slot on the endplate. I think the slot is there to work with this long vertical element on the front wing.

I did, and I mentioned this in the previous article. However, the current article is more about the progression of the wing and what the new parts do, so I can't re-chew everything from the previous article. This is where I think you were a bit picky or should have readed the previous article.

3. The flick that you talked about on one of the wings upper elements that you consulted Will Tyson about. He stated "The small flick created a tiny set of vortices to shape airflow around the front tyre." Let's analyse this, a vortex is formed by a pressure differential between two sides of an object or two or more surfaces. As it is, the vertical component where the flick mounts to curves outwards toward the endplate. This would create a vortex as the pressure gets higher on the side closer to the endplate and lower on the other side. Agree? Now, if you add that flick it actually creates a situation where the pressure gradients are evened off a bit as you move along the flick to the edge, this is a result of the flick being at a neutral angle of attack to the airflow. Therefore the flick would actually reduce the size of the vortex and reduce drag a bit off of that element. I personally think the flick is there so the vortex coming off of that vertical section (had the flick not been there) would interfere with the small turning vane next to it that was changed into a purely vertical turning vane.

Yes and no. Remember that the flick was a 2013 solution. Back then the vane it was attached to was straight. I personally believe it enhances the vortex: it creates lateral and longitudal a pressure difference, instead of just in one plain.

4. "a wing producing more downforce without stalling at higher speeds." Do some reading on wings, increasing the speed through a multiple slot wing like this will not make it stall. Definitely not at the slow (relatively) speeds that F1 cars run. If you disagree with this statement then please I would love to see some references to material stating that this happens.

Remember: the tire wake is very close to the underside of the underside of the wing. Even though it is evident teams put massive resources into reducing this effect, it still has a big impact. It makes the wing as a total much more prone to stalling. So I disagree, and since you are the one questioning this I think it's up to you to find reference to prove the contrary, because more slots in a downforce producing wing with a high AoA always had the function of ensuring the wing wouldn't stall. Again, I could be wrong, but since you are the one trying to make a point out of reference material, I'd say it's up to you first.

5. "Since the footplate doesn’t bend upwards in that region, it looks to keep airflow attached" again, why would the footplate bending upward in that region make it stall. High pressure sides of wings aren't the sides that stall. I don't know why they have the slots there, this has interested me as well and I want to do some research on it but I can almost assure you that the slots aren't there to reduce pressure on top the footplate to preventing it from stalling. My only guess would be to bleed pressure from the top of the footplate to encourage airflow to move into this area from the main wing elements.

I think you also were a bit picky here and trying to make a point out of a small, unimportant line, ending with the same conclusion as me. I didn't claim it would stall in that position. As mentioned it doesn't have an AoA. Rather, I think they want to keep airflow as attached and close to the footplate as possible, speeding it up. I only mentioned "doesn't bend upward" to clear it out. Your explanation basicilly tells the same thing: it drops pressure, sucking higher pressure from the wing elements and thus bending it outwards.

6. "It’s to be noted that the base of tire creates a turbulent and very draggy vortex." The tyres do produce a lot or drag and create a lot of turbulent air but there is nothing to suggest that they create a vortex in the traditional sense. Airflow can be turbulent without a vortex being present.

Check out this article:
http://mccabism.blogspot.be/search?upda ... date=false
And especially this picture:
http://2.bp.blogspot.com/-I4hkeoYDFPk/T ... w+drag.jpg
I don't think it's an ice cream cone there, now is it? That's a vortex right coming off the base of the tire.

7. "The second wing element has very little AoA, but due the placement of the strakes it still creates a fairly amount of downforce for only a very small drag penalty." The second element is also the largest in terms of area so you can bet that it produces quite a large amount of downforce. Also you cannot think of this wings in terms of individual elements as all the elements work together as one wing.

Yes I know the wing works as a whole. However, often it's nice to look at localized area of the wing and what solutions are being put in that small region. The big picture is very important, but teams do employ small solutions here and there to make specific parts work on their own better.
Yes It's a big surface, HOWEVER notice that the part in front has a negative AoA (for downforce) and the spoken second element is more or less flat. They are a bit stacked, and although element 1 on its own would create lift, in conjuction with the other elements forms a venturi tunnel. This like you mentioned the bigger picture. However, taking element 1 and 2 into isolation there wouldn't be so much downforce created. A big surface still needs to have some sort of AoA to create downforce in the first place. Ask someone with the mathmatical background.
However, this wasn't the point either I wanted to make, and either I put more focus on the subject itself to get people loose the point (that the underbody strakes create a venturi tunnel) or you are focussing yourself too much on the words. The main point was: strake 1 and 2 form venturi tunnel underneath element 2, increasing its downforce production.

8. "Strake 4 is longitudinal straight, but latitudinal it has bent over its complete length. Important to know is that the strake is position right next to the inner edge of the tire. At the back end of the bent part of the strake, it creates a strong vortex at the tip, shielding airflow." Again, vortices are only created when there is a pressure differential. Strake No 4 is perfectly straight and aligned with the airflow under the wing. This means that the pressure is almost perfectly even between the left and right side of the strake which means no vortex. Also, that close to the ground, it is very hard to produce a vortex simply because of being that close. If you don't believe me then take a look at this, when a plane comes into land it encounters what is known as ground effect. Ground effect affects wings up to about a wingspan away from the ground. When the wing reaches about this distances the wing becomes much more efficient as a result of ground effect. One of the causes of this is the reduction in wing tip vortices. Why is it not possible that strake No 4 could simply be there to keep the airflow laminar and keep the airflow straight going to the inside of the tyre.

I was wondered if it did this only yaw, or also when straight up. I still am in believe it creates a vortex. Certainly not a powerful one, I agree with you there, but a small one. And yes, I also have to agree it would keep airflow laminar.

9. "they create a vortex right above the strakes. Air between the strakes and the underside of the wing tends to stagnate, which creates drag. Creating a vortex in front of the stagnated air re-energizes the air there and speeds it up." Yes the overt generators there do push a small vortex through the slot gap of the wing but one minor point. Air on the underside of the wing (the low pressure side) does not stagnate. It actually speeds up in airflow, it is this acceleration in airflow that creates a low pressure and hence the pressure differential between the top and bottom of the wing and therefore the downforce on the wing. The slot gaps are there to stop the airflow from separating and becoming turbulent by feeding more air into the low pressure side. Yes as you can imagine this decreases downforce. It also allows you to run a much higher angle of attack which increases downforce more than the loss from the slot gap. That trade off is a drag increase which F1 designers are happy to live with. The vortex generators are another method to keep airflow attached to the bottom of the wing.

I think it does slow down atleast. Yes I know what airflow normally does underneath a wing. However, the strakes provide a small obstruction to the airflow. It's tiny, and the effect of it is small (I have choosen my words poorly. It doesn't stagnate, just slows down a bit compared to the airflow around it).

You have to understand that in essence what a vortex generator and a slot gap do to the velocity is contrary. A slotgap introduces high pressure air, to keep airflow attached, a vortex generator speeds up airflow dropping pressure. The vortex generators wouldn't be there if airflow slowed down more just above the strakes. If you want I'll draw that out to make it more clear. But it's factually wrong that the combination of a slotgap and a vortex generator would increase downforce. They work against eachother.

In reality those particular vortex generators are very tiny solutions; the problem it tries to solve is a very, very small one. Hence why a lot of teams don't bother with it. I'd even dare to say Mercedes has them more to block marbles from clogging up the slot gap.

I'm sorry this is so long and I don't intend to sound demeaning but please take a look at the things that I stated. If you have any questions I'll be happy to provide evidence to back up anything I said here.

Generally I liked the criticism, and there are some good points you made. If we omit some things where discussion isn't really needed to, like the discussion of whether or not the second elements creates a little, average or a lot of downforce, and focus more on things like strake 4, and for my part even on what the 2013 flick and endplate did, then I think this will be a very good debate.

[turbof1]

Some further thought on strake 4, and I feel I was right.

First of all, you speak of ground effect, but the strake isn't as close to the ground as the lowest part of the wing is. Indeed the strake starts rather high up the second element. While ground effect would probably still have an effect, it's less pronounced. How exact is yours or my guess: we both don't have access to cfd. But it doesn't run as low as the lowest edge of the front wing, that's undeniable.

Second, I took some effort into drawing the airflow:

(It's a bit simplified, but you get the idea).
This is what you said:

Strake No 4 is perfectly straight and aligned with the airflow under the wing.

I reject that statement: airflow underneath the wing tents to follow the curve of the wing, especially with all the slot gaps trying to keep airflow attached to the wing. The airflow bents upwards, so is not straight.

The high energy air will tent to follow the curve of the strake, bending around it. This makes the the outside and underside of the strake low pressure. But because the shape of the strake blocks low pressure air from going to the inside of the strake, and because the slot gaps introduce airflow of higher pressure into the inside, the inside of the strake is high(er) pressure. That's your pressure difference, and that'll create a counter-rotating vortex at the tip.

[trinidefender]

Some further thought on strake 4, and I feel I was right.

First of all, you speak of ground effect, but the strake isn't as close to the ground as the lowest part of the wing is. Indeed the strake starts rather high up the second element. While ground effect would probably still have an effect, it's less pronounced. How exact is yours or my guess: we both don't have access to cfd. But it doesn't run as low as the lowest edge of the front wing, that's undeniable.

Second, I took some effort into drawing the airflow:
http://u.cubeupload.com/turbof1/Strakepurpose.jpg
(It's a bit simplified, but you get the idea).
This is what you said:

Strake No 4 is perfectly straight and aligned with the airflow under the wing.

I reject that statement: airflow underneath the wing tents to follow the curve of the wing, especially with all the slot gaps trying to keep airflow attached to the wing. The airflow bents upwards, so is not straight.

The high energy air will tent to follow the curve of the strake, bending around it. This makes the the outside and underside of the strake low pressure. But because the shape of the strake blocks low pressure air from going to the inside of the strake, and because the slot gaps introduce airflow of higher pressure into the inside, the inside of the strake is high(er) pressure. That's your pressure difference, and that'll create a counter-rotating vortex at the tip.

The problem with this is how a vortex forms. Yes the 4th element is further away from the ground but relative to its wing span it is still relatively close and still affected by the ground. The vortex is noticeable from the back however it begins to form at the front of wingtip, in this case strake tip. The front is very far forward and either way the whole bottom edge of the strake is VERY close to the ground. Being that close to the ground stops the rotation of air around the edge to a large degree

[turbof1]

The problem with this is how a vortex forms. Yes the 4th element is further away from the ground but relative to its wing span it is still relatively close and still affected by the ground. The vortex is noticeable from the back however it begins to form at the front of wingtip, in this case strake tip. The front is very far forward and either way the whole bottom edge of the strake is VERY close to the ground. Being that close to the ground stops the rotation of air around the edge to a large degree

But neither of us know to exactly what degree. I do feel you are exaggerating it. Vortices still form at the endplate tips at its back (Not at the front as you said, simply because the strake keeps high and low pressure seperated until it reaches its end) and that is closer to to ground. A vortex will form at the strake's tip, and Mercedes specifically shaped the strake in order to create a vortex of the desired shape.

Again it doesn't take a very powerful vortex (neither is this wanted) to shield the airflow from the tyre wake. More importantly is to extent the blockade the strake forms further back. If possible just past the tyre, although I agree with you that'll be difficult. Teams use what they can.
So in short I agree that ground effect will have an effect, a considerable effect, but not to the point the vortex becomes unuseable. And I do think mercedes tries to shape a very specific vortex at that point.

I'll ask clarification from Somers and Scarbs; it is very difficult to make something conclusive when there's no cfd available.

EDIT: scarbs on the subject:

The strake is used to offset the tyre squirt from the interface of the tyre thus preventing it choking the front wing flow.
I understand a vortex is used, the spanwise flow under the wing meeting the fence creating the required vortex. Front wings have quite high ride heights nowadays, while ground effect is still there its effect is diminshed. I see no reason why any surface under the wing would not create a strong vortex

[flyboy2160]

....
I'll ask clarification from Somers and Scarbs; it is very difficult to make something conclusive when there's no cfd available.

EDIT: scarbs on the subject:

The strake is used to offset the tyre squirt from the interface of the tyre thus preventing it choking the front wing flow.
I understand a vortex is used, the spanwise flow under the wing meeting the fence creating the required vortex. Front wings have quite high ride heights nowadays, while ground effect is still there its effect is diminshed. I see no reason why any surface under the wing would not create a strong vortex

Scarbs has a lot of excellent mechanical analyses, but too often in the past he's been completely off base when it comes to aero when he's on his own (i.e., not repeating something from a team.)

Based on both actual flight testing and CFD running, I'll bet that the pressure field on the down side of the wing would be a large portion of or comparable in order of magnitude to the wing chord in free stream. Since even the current wings are much closer than this to the ground, there's no way the ground isn't affecting the wing flow.

If anybody has a wing model, I'll run it in viscous CFD both free steam and next to the ground.

[PlatinumZealot]

Turbo, the diagrams in your articles are very informative.

One of my criticisms is the heft of words given to each upgrade. Sometimes the descriptions are drawn out and not that accurate. Some descriptions bring up some questions of credibility: no single one of us know exactly why Mercedes has put every piece and flap and turn where it is so I think there is need to pressure your self in trying to explain everything. Just a simple description would have done just fine most of the time.

I quite like just browsing over the diagrams and small description or two. Explanations without citations, scripted knowledge or any CFD are pretty much bring in too many questions - even when written by the great Garry Anderson

[turbof1]

I first like to say these articles are opinion pieces - I'm careful with my word use, making sure they are expressed as an opinion. There are a lot of instances where I could be wrong.

Second, I also make these articles to learn something from it myself. I very much like the ground effect debate. It enables extra insight. Understand that I don't have an educational background on this. So I do have to learn through trial and error. I love and appreciate the feedback; they help out a lot.

Perhaps the biggest contribution they give is that they generate very useful discussion. Since when did we have this kind of technical and relevant debate inbetween race weekends? That has been a long time ago.

If you feel there's too much text, then of course I can adapt to that as well. Infact I'm currently working on the Williams front wing, so I could try to implement your ideas.

[dren]

Perhaps the biggest contribution they give is that they generate very useful discussion. Since when did we have this kind of technical and relevant debate inbetween race weekends? That has been a long time ago.

If you feel there's too much text, then of course I can adapt to that as well. Infact I'm currently working on the Williams front wing, so I could try to implement your ideas.

1. Agreed
2. I like the amount of detail.

[flyboy2160]

Car threads are for actual car parts, not hypothetical updates. If those become real car parts, they can be discussed in the car threads.

[stefan_]

Great Britain 2014 - Thursday (03.07.2014)

[stefan_]

Great Britain 2014 - Friday (04.07.2014)