McLaren MP4-29 Mercedes

[SectorOne]

Why would Red Bull go that route? With a gradient and virtually no horizontal floor space from edge to sidepod?
And i take it STR in 2012 was too extreme?



Maybe a mod can just break this off to a thread? Sorry about that, i´m just curious about the thought concept of this whole thing.

[Gaz.]

I would say that the large undercut is trying to get as much air as possible to rear of the car. The larger the undercut, the less likely air flow could leak from the top of the floor to underneath it and disturbing the flow underneath the car. Also, the larger and tighter the undercut, the faster the velocity of the air is around the sidepods as a stronger low pressure region is created around them and towards the coke bottle area thus increasing the velocity of the air which would then flow on top of the diffuser increasing downforce. Obviously if the sidepod undercut is too aggressive, then there is chance the air flow will stall so there is a balance of increasing the velocity of the airflow around the sidepods and towards the coke bottle without stalling it.

So I presume this undercut wouldn't work properly with those large wishbone fairings? I'm not an aero man at all, but the wishbones appear to be counter productive to what you've just said- to this layman anyway

[trinidefender]

I would say that the large undercut is trying to get as much air as possible to rear of the car. The larger the undercut, the less likely air flow could leak from the top of the floor to underneath it and disturbing the flow underneath the car. Also, the larger and tighter the undercut, the faster the velocity of the air is around the sidepods as a stronger low pressure region is created around them and towards the coke bottle area thus increasing the velocity of the air which would then flow on top of the diffuser increasing downforce. Obviously if the sidepod undercut is too aggressive, then there is chance the air flow will stall so there is a balance of increasing the velocity of the airflow around the sidepods and towards the coke bottle without stalling it.

So I presume this undercut wouldn't work properly with those large wishbone fairings? I'm not an aero man at all, but the wishbones appear to be counter productive to what you've just said- to this layman anyway

There seems to be some confusion about those wishbones. At first glance all they seem to do block the airflow hence why many have called them blockers. I would say the term "blocker" is actually a misnomer. Think about it this way, if a car is moving through the air, the air is GOING to flow around it somehow. So on the McLaren there is the air flowing toward the back of the car along the floor. The air then hits the suspension mushrooms (what has been termed as blockers). The airflow has to go somewhere. It can't go straight through obviously except in the small gaps. It can't go underneath as the diffuser roof is there. It only really has one direction to go, upwards at an angle. Therefore behind the suspension mushrooms will be a low pressure zone that increases the pressure differential in the diffuser and hence pulls more air through it increasing downforce.

Now onto the whole undercut thing. Remember that, like everything else in Formula 1, undercut comes with a compromise. The more undercut you have, the higher up all the pieces in the sidepods will be increasing the centre of gravity. The sidepods are more complicated than most think and one place where the aero guys have to work hand in hand with the cooling guys. The cooling guys know how much cooling they need and therefore the size of radiators and airflow figures that these radiators need. The aero guys then have to take these radiators and figure out how exactly to lay them to figure out car exterior aerodynamics traits, car internal aero and and packaging (C of G) constraints.

Why the undercut you say? Well think of it this way. Starting from the front of the T-tray, above the floor, what is the shortest and fastest point to get airflow to the top of the diffuser? It is along the floor. The more you put in the way on the floor the more the airflow has to go around and divert its flow. It should then hold true that the larger you have an undercut the less there is in the way of the airflow restriction to the rear of the car. Now you throw in the shape of that car. From a purely minimising drag way of thinking the most ideal shape would be something along the lines of a constant radius turn with the largest radius (think of it as a smaller angle change over a larger distance) possible. It is the shape that provides the most gradual pressure gradient. It also has the greatest chance of keeping the flow laminar however laminar flow is a whole other kettle of fish.

The lower the pressure gradient the lower the drag. Of course all my explanations were extremely simplified but I hope it helps people somewhat. Just remember that more isn't always better and, especially with sidepods, everything is a compromise, no more so than the whole undercut issue.

P.s. To the mods, I answered here but I feel as if the last few posts about undercut should be in their own respective thread.

[dren]

I still think the rear of the engine cover looks so bulky, when compared to other cars.

Definitely!
We haven't seen the slimmed down side pods that was speculated early in the season.

Seems like the radiator layout is the reason for the sidepod shape. But was this done to make the rear wishbone devices work better? It looks like they wanted to exhaust the cooling flow higher than the rest.

[bhall II]

Yes you wonder how it works at all really. Odd [radiator] layout.

I posted a gratuitously long and speculative missive about it here.

Basically the idea is to control air flow through the radiators via a pressure differential between the intake side and the exit side of the sidepod. If the radiator is installed within the plenum such that it completely divides the high-pressure intake side from the low-pressure exit side, air will be pulled through the radiator regardless of its orientation to incoming air flow. In other words, it's unnecessary to mount the radiators anywhere near vertically in order for cooling flow to pass through them. (WIthin some constraints) as long as there's less pressure on the exit side of the radiator than there is on the intake side, it could be mounted parallel to the ground, and air flow will still pass through it.

[flyboy2160]

Yes you wonder how it works at all really. Odd [radiator] layout.

I posted a gratuitously long and speculative missive about it here.

Basically the idea is to control air flow through the radiators via a pressure differential between the intake side and the exit side of the sidepod. ... air will be pulled through the radiator ...

To be nitpicky, in a classic non-Meredith plenum, the higher pressure on the intake side drives the air through the radiator. That's why the plenum cross section area increases away from the opening. As the air slows, its pressure increases. This is what drives the air through the radiator - it's not sucked through from the back side. The lower pressure on the back side is due to the air passing through the restrictive fins of the radiator. There isn't a low pressure area there sucking the air through.

[bhall II]

To be really nitpicky, that's not so much nitpicky as it is a complete repudiation. I can accept it, though.

(I still think teams use Meredith for drag-reduction, though. And that's still partially your fault. )

[trinidefender]

Yes you wonder how it works at all really. Odd [radiator] layout.

I posted a gratuitously long and speculative missive about it here.

Basically the idea is to control air flow through the radiators via a pressure differential between the intake side and the exit side of the sidepod. ... air will be pulled through the radiator ...

To be nitpicky, in a classic non-Meredith plenum, the higher pressure on the intake side drives the air through the radiator. That's why the plenum cross section area increases away from the opening. As the air slows, its pressure increases. This is what drives the air through the radiator - it's not sucked through from the back side. The lower pressure on the back side is due to the air passing through the restrictive fins of the radiator. There isn't a low pressure area there sucking the air through.

flyboy2160 what? You do realise that airflow always goes from high pressure to low pressure right? That means that it doesn't matter if the air pressure is higher on the (radiator) intake side, lower on the exit side or a combination of the two. All that matters is that there is a pressure differential there. The higher the pressure differential the higher the force on the air to move through the radiator fins.

bhall almost all radiators are set up that way, even on road cars. You will notice that manufacturers tend to seal the area around radiators so that there is a larger pressure differential between each side of the radiator and airflow is forced/pulled through the radiator making a radiator much more efficient than it would be if airflow would be allowed to go around the radiator.

While ducting does help to turn the airflow through the radiator, your explanation doesn't take into account things like turbulence and things like that. Having a radiator on the vertical plane is still ideal when it comes to getting flow through the radiator.

[bhall II]

[...]

bhall almost all radiators are set up that way, even on road cars. You will notice that manufacturers tend to seal the area around radiators so that there is a larger pressure differential between each side of the radiator and airflow is forced/pulled through the radiator making a radiator much more efficient than it would be if airflow would be allowed to go around the radiator.

[...]

And here I've been, this whole time, thinking those shrouds served to protect fingers. Learned something new today.

[flyboy2160]

...
flyboy2160 what? You do realise that airflow always goes from high pressure to low pressure right? That means that it doesn't matter if the air pressure is higher on the (radiator) intake side, lower on the exit side or a combination of the two. All that matters is that there is a pressure differential there. The higher the pressure differential the higher the force on the air to move through the radiator fins....

No, you're wrong. When you do an actual engineering analysis of these things (which I have) instead of the typical F1T non-number pseudo-science by non-engineers and non-scientists, the analysis is as I described it. The incoming air energy is the driver. The outlet and radiator downstream flow path have an influence, but you always start with the properties of the incoming air as the main driver of the flow.

[trinidefender]

...
flyboy2160 what? You do realise that airflow always goes from high pressure to low pressure right? That means that it doesn't matter if the air pressure is higher on the (radiator) intake side, lower on the exit side or a combination of the two. All that matters is that there is a pressure differential there. The higher the pressure differential the higher the force on the air to move through the radiator fins....

No, you're wrong. When you do an actual engineering analysis of these things (which I have) instead of the typical F1T non-number pseudo-science by non-engineers and non-scientists, the analysis is as I described it. The incoming air energy is the driver. The outlet and radiator downstream flow path have an influence, but you always start with the properties of the incoming air as the main driver of the flow.

There is no such thing as a "driver." Air always moves from high pressure to low pressure. That is a fact. I didn't explicitly disagree with your statement, all I did was point out that on any radiator there has to be a pressure differential for air to flow through it. Whether that pressure differential comes from high at one side or low at the other is largely irrelevant.

Think of it this way. A radiator on a static ICE such as a generator. If there is no fan on the radiator then all the heat that the radiator (heat exchanger) rejects to the air will come from the radiator rejecting heat through conduction, and maybe one other form of thermal transfer, to the surrounding air.

Now, if you add a fan to the front of a radiator you get a higher pressure in front of the radiator pushing the air through. If you add a fan to the back of the radiator but this time sucking air then you get the same pressure differential. The difference is that in scenario A you get the higher than ambient pressure on the front vs ambient at the back while in scenario B you get ambient at the front with lower than ambient at the back. Either way there is a pressure differential there which causes the airflow to move through the radiator.

Btw next time stop trying to sound so condescending. As far as I can see you provided no such numbers, you didn't provide any sources and neither did you do it in a very scientific manner. We aren't 12 here so I ask that you keep immature things like that to yourself.

[zioture]

MCLAREN TECHNICAL ANALYSIS “SERRATED” REAR WING

The new edges on the rear wing of the McLaren, seen at Hockenheim, was much talked about, so we decided to go deeper to understand the principles on which they are based. You can definitely notice a “jagged” profile in the leading edge of the second plane, the upper one, which connects at the DRS system.

You can see the same thing on the trailing edge of the lower profile. I will try to explain how the first element belonging to the DRS system. It is known that whenever air finds an obstacle, it clearly collides and generates an area of high pressure area on the front of the obstacle precisely because of the arrest of the air flow.

We are looking at the wing from above and not from the top as the previous figure shows. Notice the high-pressure line follows around the edge since this is placed to be perpendicular to the motion of the air flow.

If you decided to use a serrated leading edge just as the McLaren has, we could see that instead of nearly all of the entire profile being perpendicular to the flow, only small portions are perpendicular and other portions are oblique. The pressure increases in lower amounts and the flow is not slowed down. In doing so, first we shrug off a good portion of aerodynamic drag and create another advantage: since the air strikes more violently it surely cannot mean that it slows down. It takes less kinetic energy to recover speed loss due to the air crash. This means that the entire first part of the wing will be surrounded by a flow velocity greater than the previous solution in which the edge was straight. This increases the relative speed of the air with respect to the wing, a phenomenon which also leads to an increase in downforce.


READ ALL
http://www.newsf1.it/mclaren-technical- ... wing-2071/

[PhillipM]

If it was that simple, every team would have it on their wings, and mclaren would have it on the leading edge of theirs, which they don't.

[r.t.1.n]

Russland GP

[Thunder]

Russia, Thursday via AMuS:

The upper Elements of the Front Wing are different.