2016 Mercedes AMG Petronas F1 Team - Mercedes

[bhall II]

But I have to repeat, I still see no evidence to suggest that Rake will not create more drag at speed.

There's a tidy explanation which still points to higher rake meaning higher drag. I dunno if we going round in circles yet, but it does seem this point has not been surmounted.

Maximising the downforce of the diffuser is, however, a subtle issue. The downforce generated by a diffuser is a function of two variables: (i) the angle of the diffuser, and (ii) the height above the ground. Generally speaking, the peak downforce of the diffuser increases with the angle of the diffuser. Then, for a fixed diffuser angle, the downforce generated will increase according to an exponential curve as the height reduces, until a first critical point is reached (see diagram above, taken from Ground Effect Aerodynamics of Race Cars, Zhang, Toet and Zerihan, Applied Mechanics Reviews, January 2006, Vol 59, pp33-49). As the height is reduced further, the downforce will increase again, but according to a linear slope, until a second critical point is reached, after which the downforce falls off a cliff.

There are five different diffusers (or angles) plotted on the graph, and they're represented by curves that depict downforce coefficient as a function of both increasing ride height and decreasing ride height.

In line with your tidy explanation, please identify the diffusers (or angles) for which any deviation from optimal ride height - indicated by their respective points of peak downforce - results in an increased downforce coefficient, thus an increased drag coefficient.



And yes, we're definitely chasing our tails here.

[FoxHound]

In line with your tidy explanation, please identify the diffusers (or angles) for which any deviation from optimal ride height - indicated by their respective points of peak downforce - results in an increased downforce coefficient, thus an increased drag coefficient.

http://i.imgur.com/vrNutbm.png

And yes, we're definitely chasing our tails here.

I'm learning as I go man, it's some next level stuff(For me anyway).

However, you did write this a couple months ago...

.... it's my belief that rake is a consequence of lowering the ride height of the front wing in order to increase downforce. Since doing so enhances ground effect, the increase in downforce is accompanied primarily by increased induced drag. Adding the same amount of downforce through higher AoA alone would add both induced drag and parasitic drag. (It's also not always possible, because there's a practical limit to AoA, and it tends to be lower at higher ride heights.)

Pertaining to a question surrounding "pitch" or rake".

We also had AMuS on hand to handily provide some info on that...


Using that explanation of yours, and the AMuS graph, would it not be a good bet to suggest that the Red Bull would run more drag than a similarly winged Mercedes?

[bhall II]

Using that explanation of yours, and the AMuS graph, would it not be a good bet to suggest that the Red Bull would run more drag than a similarly winged Mercedes?

I'm not sure what you mean by "similarly winged."

Hypothetically, if two cars have the same level of downforce, but are optimized around different rake angles, the more highly raked car would likely suffer a lesser drag penalty than the other car, because rake adds downforce in just about the most efficient manner possible (under current rules), making the other car the draggier of the two by default. You can even flip it around: of two cars with the same level of drag, but different rake angles, the more highly raked car would likely be the one that produces more downforce (which is Red Bull's approach to aero).

That's the point I was trying to make with the bit you quoted.

Again, there are caveats aplenty. But, this is the foundation.

[FoxHound]

Using that explanation of yours, and the AMuS graph, would it not be a good bet to suggest that the Red Bull would run more drag than a similarly winged Mercedes?

I'm not sure what you mean by "similarly winged."

Hypothetically, if two cars have the same level of downforce, but are optimized around different rake angles, the more highly raked car would likely suffer a lesser drag penalty than the other car, because rake adds downforce in just about the most efficient manner possible (under current rules), making the other car the draggier of the two by default. You can even flip it around: of two cars with the same level of drag, but different rake angles, the more highly raked car would likely be the one that produces more downforce (which is Red Bull's approach to aero).

That's the point I was trying to make with the bit you quoted.

Again, there are caveats aplenty. But, this is the foundation.

Ok Ben,

I'm taking this up with some professors, I'll get back to you on this within a few days.

[bhall II]

Is it really that difficult to accept?

[turbof1]

Is it really that difficult to accept?

Remember when I had that with you? Those were fun times .

Also, what is all of this doing in this topic? I welcome the level of conversation though, so I think I will search tomorrow for a suitable topic to move posts into.

[Juzh]

Hypothetically, if two cars have the same level of downforce, but are optimized around different rake angles, the more highly raked car would likely suffer a lesser drag penalty than the other car, because rake adds downforce in just about the most efficient manner possible (under current rules), making the other car the draggier of the two by default.

Case in point: post summer RB9 vs W04.

[bhall II]

Put a different way, it might be easier to understand.

Of two cars with identical downforce coefficients, which one will likely have the lower drag coefficient: the one that derives a higher percentage of total downforce from its undertray (more rake), or the one that derives a higher percentage of total downforce from its wings (less rake)?

In reality, it's not that simple. But, it's close enough for this conversation.

[SameSame]

Why does a lower ride height and a lower AoA diffuser generate the same downforce as a higher ride with a relatively higher AoA diffuser? Is this due to ground effect? And if it is due to ground effect, isn't the whole point of rake to be able to run a higher rear end with a steeper AoA diffuser? Could this graph show that even though Mercedes run less rake they could still be generating similar diffuser performance as Red Bull?

Sorry if this sounds stupid, I find aero so interesting but am only in the process of learning the basic fundamentals

[SiLo]

The Mercedes still has quite a lot of rake, it's just that as soon as it's moving quickly it seems a lot less notable. Could be that they have gone for much better suspension mechanics and geometry gaining laptime that way.

[FoxHound]

Is it really that difficult to accept?

I'm running sans first hand sources here Ben, but I'm giving it a go.

At speed, as you mentioned, the car generates it's DF(most anyways) from the floor. This is aided by the rake with low front wing. But, this is at speed, and at speed the pitch of the car effectively stalls the rear wing(not in entirety).
We know the front wing is of a larger surface area than that of Mercedes, so there's that.

And the rear wing will also have a negative impact on drag, up to a certain point in rake angle
And this angle is not uniform, and will also have certain drawbacks relating to set up and tyre wear. For example, If anti dive is being implented on a car with a wing 1 cm above the ground at 200mph, the front tyres will feel more of the transition of energy, more of the time, than a car with less rake.

It also has more drag at lower speeds until the magic switchover point occurs. Again, this point is not uniform and will vary venue to venue. But it is interesting that Red Bull suffered most at Baku, where the tyres were not understood in relation to set up(skinny wing).
Also, the set up sweetspot changes as fuel load increases/decreases. To me, this indicates you are running compromised for at least 50% of the race, as over-rotation of the rear wing will lead to high drag, the same applies for under rotation of the rear wing.

It's also been mentioned to me that the rear wing needs to be overloaded before rotation of the wing(compressing the suspension/rake) can occur. Car's with less rake also benefit from the rear wing being stalled, to fraction less according to rake angle. This in itself is evidence that it will have much higher drag prior to transition.

And a loaded dice...

"The Red Bull, for example, is a car that functions well where high drag isn't penalised as much as at other types of circuit. So, in wet conditions and at low-speed circuits such as the Hungaroring, they are a major threat.

https://www.formula1.com/en/latest/head ... ngary.html

[bhall II]

Characterized by short straights, a circuit that doesn't penalize excessive drag is also a circuit that doesn't punish power deficits. As such, I don't know that there's anything to be gleaned on that front.

With regard to the aero, it looks as though you've stumbled upon the latest analysis from motorsport.com. Frankly, there's not much about it that makes a whole lot of sense.

First, I don't know how you overload a wing. It sounds like something that would increase the size of the car's wake, which is bad.

I also don't know how a drag-reduction system that literally relies upon induced drag (downforce) can work. Anything that's activated by the lower ride height caused by aero loading will stop working the very moment it starts working, because reducing induced drag (downforce) will cause ride height to return to its baseline setting, and then you're back at square one.

Lastly, I can't figure out how "rotating" a wing is supposed to invoke a stall if the rotation effectively reduces the wing's AoA.

So, where does that leave us? (Waaaaaaaay off-topic. )

[Cold Fussion]

First, I don't know how you overload a wing. It sounds like something that would increase the size of the car's wake, which is bad.

It's pretty simple, you overload the rear wing, it consequently falls off and then you have less drag!

[FoxHound]

Characterized by short straights, a circuit that doesn't penalize excessive drag is also a circuit that doesn't punish power deficits. As such, I don't know that there's anything to be gleaned on that front.

And yet Red Bull soundly beaten in Hungary. Circa 30 seconds IIRC.

I also don't know how a drag-reduction system that literally relies upon induced drag (downforce) can work. Anything that's activated by the lower ride height caused by aero loading will stop working the very moment it starts working, because reducing induced drag (downforce) will cause ride height to return to its baseline setting, and then you're back at square one

Not if, and as you said, the floor is generating the majority of the downforce. Once the rake has done it's work, the floor DF takes over, and this is where the efficiency ie less drag penalties as per your graphs, is outlined.
Obviously this applies at certain speeds, as to when it's "activated" or "deactivated".

Lastly, I can't figure out how "rotating" a wing is supposed to invoke a stall if the rotation effectively reduces the wing's AoA.

Depends on the wing angle and the suspension set up. That the wing changes angle as the suspension squats is a given, it has to.
As speed builds, and the wing is taking more energy, the aerodynamicists will know at which speed the stall is likely to occur.
The suspension may also have soft travel for the first few mm's and a steadily increasing resistance for each mm thereafter, or even an intermingled set up to help the effect.

So, where does that leave us? (Waaaaaaaay off-topic. )

It's relevant to a degree, with Merc monstering "chassis aero teams" at "chassis aero tracks"....

[bhall II]

- The Hungaroring, with its slow, sweeping corners, is also a circuit that rewards driveability. (This aspect of the comparison is almost a chicken-egg thing.)

- It doesn't matter what generates the downforce. Any drag-reduction measure that relies on reduced ride height for activation will defeat itself upon activation.

Further, if RB12 has the sort of floor efficiency that could affect such a change without the rear wing, then it wouldn't a need a rear wing at all.

What made Red Bull's flexible front wings work is that they were anisotropic, meaning they were activated by neither downforce nor drag force independently of the other. They required the influence of both, and I don't know how you do that with an entire chassis.

- Unless the rear wing is somehow rotated forward against the force of drag, rotation will reduce AoA. That means its highly unlikely the wing will stall, because the rotation will minimize the impact of the adverse pressure gradient that causes wings to stall.

(Seriously, whoever wrote that bit for motorsport.con really --- the bed.)

It's pretty simple, you overload the rear wing, it consequently falls off and then you have less drag!

Far more sensible than what was reported.