Red Bull RB16B

[godlameroso]

Wouldn't positive toe on the rear tyre force the tyre squirt away from the diffuser instead of into it?

I always ran positive rear toe during my rFactor days.

Sorry I’m not aware as to what “positive” toe is — would that mean toe in or out? With the other direction of course beign “negative”

Positive is toe in, negative is toe out. It's common to get the two confused. If you move the leading edge of the tire away from the floor, you move the trailing edge closer to it. You also make the car rotate more.

[Marti_EF3]

Wouldn't positive toe on the rear tyre force the tyre squirt away from the diffuser instead of into it?

I always ran positive rear toe during my rFactor days.

Sorry I’m not aware as to what “positive” toe is — would that mean toe in or out? With the other direction of course beign “negative”

Positive is toe in, negative is toe out. It's common to get the two confused. If you move the leading edge of the tire away from the floor, you move the trailing edge closer to it. You also make the car rotate more.

Problem is, with toe in, you may cause overheat on the rear tires, right? Also with tire wear... I was trying a few setups with my car because I want my rear tires to warm better and faster

[Zynerji]

Wouldn't positive toe on the rear tyre force the tyre squirt away from the diffuser instead of into it?

I always ran positive rear toe during my rFactor days.

Sorry I’m not aware as to what “positive” toe is — would that mean toe in or out? With the other direction of course beign “negative”

Positive would be toe out in rFactor.

Toe in is great for self straightening while applying power out of a corner, but my driving style was always "severly" flattered by toe-in on front (2-3 degrees) and toe out on the rear (0.5-1.5 degrees).

Then crank up the 3rd springs front and rear, set front corners 30% stiffer than the rear corners.

Drives very "swoopy".

I should set my wheel up again... I miss it.

[godlameroso]

Sorry I’m not aware as to what “positive” toe is — would that mean toe in or out? With the other direction of course beign “negative”

Positive is toe in, negative is toe out. It's common to get the two confused. If you move the leading edge of the tire away from the floor, you move the trailing edge closer to it. You also make the car rotate more.

Problem is, with toe in, you may cause overheat on the rear tires, right? Also with tire wear... I was trying a few setups with my car because I want my rear tires to warm better and faster

Toe in is more stable, because the loaded wheel is pointing in the same direction as the turn.

[godlameroso]

Wouldn't positive toe on the rear tyre force the tyre squirt away from the diffuser instead of into it?

I always ran positive rear toe during my rFactor days.

Sorry I’m not aware as to what “positive” toe is — would that mean toe in or out? With the other direction of course beign “negative”

Positive would be toe out.

The positivity or negativity has to do with where where the wheel points when the car is turning. If the toe matches the direction of the loaded wheel during a corner it is positive. With toe out, or negative toe, the tire wants to go right while you're turning left. With positive, you turn left and the loaded tire is also turning left.

With a multilink setup, you can have the car with toe out at slow speeds to help cornering while it goes to toe in* at speed, and adds stability. Remember the ride height changes both toe and camber as it compresses.

[Zynerji]

I was running high rake in 2007 (2006 cars) on that setup as well! With the stiff 3rd and softer corner springs, it would almost "lean" the back end through the corners.

I remember my friend couldn't match my 1'11" lap at Monaco with my setup, and he was so upset watching the ghost car go through the swimming pool section nearly-flat.

He did copy the philosophy and win his league championship in 2007 and 2008 though!

BACK TO MY ORIGINAL THOUGHT ON THIS:

Would going toe-out on the rears remove the diffuser interaction with tyre squirt by redirecting the squirt to the outside of the tyre instead of the inside?

[aral]

And back to the actual RB16B, please

[godlameroso]

This is a good segue into the current car and the difficulties brought by the new regulations. Rear tire squirt is a big issue.

Going back to last year, the slots increased the pressure on the face of the tire, but when the car is in yaw that pressure also shifted, which meant the pressure difference on the outboard side of the tire was greater than the inboard, because the brake ducts were also increasing the airflow outside the tire.

The static pressure is actually higher because all the airflow is moving outboard, so the airflow that's left is stuck recirculating trying to find the lowest pressure it can fill. The body work around the diffuser tries to delay that static high pressure air from getting to the low pressure zone increasing the pressure difference.

What the rules have done is hurt the ability to send the rear tire wake outboard. Instead the floor has to interact with the tire squirt directly. The tumbling air that spills off the high pressure face of the tire rushes to fill the low pressure void behind the tire.

Going to the alignment point, the way air spills off the tire will in fact be affected by alignment, and camber angle, which changes as the rake angle changes, as the car is loaded at speed. That's not all, the way the tire deforms also plays a big part in how airflow spills off the tire. Once teams understand that better, it could take a few weeks or months to start putting that understanding to optimize their designs.

Knowing all of this it will be interesting to see how RB16B is developed going forward.

This goes back to my earlier point, if you want to reduce the turbulence on the inboard side of the tire, you either increase the pressure difference on the outboard side(harder to do because of the regulations), or you lower the pressure difference inboard, by raising the static pressure behind the rear tire, right where it's moving away from the ground.

Think about how a wheel well reduces tire turbulence, and reduces drag? The air inside the wheel well is higher pressure both ahead of, and behind of the tire, so the pressure difference between the face and the transition to the low pressure region behind the tire is greatly diminished. You can't stop airflow from interacting with the tire, but you can limit its effect. By encapsulating the tire in a high pressure zone you effectively reduce turbulence by reducing the pressure difference the tire experiences. Notice I said you reduce, not eliminate, you cannot eliminate air.

[godlameroso]

The front wing and bargeboard exemplify this beautifully. The high pressure air on the face of the front wing reduces the pressure that reaches the face of the front tire. Nicely managed to go around the tire, while the bargeboards raise the pressure on the trailing edge wake of the tire reducing it's overall turbulence in one fell swoop. I would wager that the front tires are effectively managed as if the cars had front fenders with wide open louvers.

[marcush]

I fail to see how 1mm more or less toe should affect aero in any meaningfull way , if that was the case the car would simply be impossible to drive in a straight line as any minor correction on the steering wheel would umsettle the car big time.
Big steering input ( also known as induced slip angle) can have aero effects , especially with front suspension and steering geometries aimed at changing rideheights , tyre sidewall deformation under load etc.
static Toe settings add or deduct artificial slip angle to the tyre ,so there is
an influence to be found on how much grip is available as a tyre is slip angle sensitive (there is a optimum slip angle for a given vertical load )
This vertical load -optimum slip angle relation is mirrored in anti ackerman steering geometry : the lesser loaded inner front wheel has more grip with less
slip angle ,thus it makes sense to not steer it “correctly “ but keep it a bit too straight .Thats all depending on specific tyre caracteristics.
When your suspension shows bump steer characteristics , your grip will change through suspension travel as the tyre changes slip angle ...but On an aero car the influence of underfloor ride height change induced vertical load fluctuations is your main enemy .

[godlameroso]

I fail to see how 1mm more or less toe should affect aero in any meaningfull way , if that was the case the car would simply be impossible to drive in a straight line as any minor correction on the steering wheel would umsettle the car big time.
Big steering input ( also known as induced slip angle) can have aero effects , especially with front suspension and steering geometries aimed at changing rideheights , tyre sidewall deformation under load etc.
static Toe settings add or deduct artificial slip angle to the tyre ,so there is
an influence to be found on how much grip is available as a tyre is slip angle sensitive (there is a optimum slip angle for a given vertical load )
This vertical load -optimum slip angle relation is mirrored in anti ackerman steering geometry : the lesser loaded inner front wheel has more grip with less
slip angle ,thus it makes sense to not steer it “correctly “ but keep it a bit too straight .Thats all depending on specific tyre caracteristics.
When your suspension shows bump steer characteristics , your grip will change through suspension travel as the tyre changes slip angle ...but On an aero car the influence of underfloor ride height change induced vertical load fluctuations is your main enemy .

One quarter of a degree of toe is ~6mm one degree of toe is 4 times that amount, it's not insignificant.

[PlatinumZealot]

It's interesting, the only part in testing and also today in FP1 where they put some flow-viz on is on the rear-suspension:
https://pbs.twimg.com/media/ExZ2zb6XMAE ... name=large

I think I understand how the slots worked last year. They were guiding air to the low pressure region of the tire, equalizing the pressure with the higher pressure region above the floor where the air was hitting it. By reducing the pressure differential of the high and low pressure regions of the tire, it reduced the turbulence being shed by the tire.

This year I see teams trying to create high pressure region along the edge of the floor, but won't this just feed the low pressure tire squirt? Because upstream the car is shedding vortecies that are smacking into the rear tires.

From our understanding of combustion engines, we understand that swirl and turbulence both aid mixing of air and fuel, however it's not just limited to mixing air and fuel, it's also true about mixing airflows, particularly airflows of different temperatures. Like the different temperatures found in the brakes and tires relative to ambient airflow.

There are two ways to reduce tire squirt, or turbulence shed from the tire, you either lower the high pressure zone, or raise the pressure in the low pressure zone. You can change the pressure by adding heat, however adding heat also adds kinematic viscosity to air, and thus causes more skin friction on any surface, which will affect how air flows upstream. As the airflow will always migrate towards the lowest pressure it can find.

Maybe lower rake cars create more powerful tire squirt, while higher rake cars with greater distance from the floor, and closer proximity to the high pressure zone of the rear tire create a lower pressure differential in that region.

It's a shame the regulations don't let you turn the floor downward near the rear tires. All the teams want to flick the air up, but why not down, wouldn't that increase the pressure in the low pressure region of the floor weakening the turbulence being shed by the tire? It would also match the rotation of the vortex being shed by the diffuser.

The high pressure region already exists in front of the tyre. It's basically an air dam as the air hits this big blunt forward spining object head on.
The flow from it interferes with the edge of diffuser. Also the spinning and deforming wheel makes it worse.

Keep in mind, floor slots are a recent invention. If I remember the floor slots were seen first on a Ferrari after holes in the side pods were banned, Ferrari cut slits to keep "holes" for the exhaust gills on the side pod. Then this same trick was used to make "holes" then to be slots in the edge of the floor after exhasust blown diffusers were banned. If I remember correctly!

But anyway.. The floors managed to acheive a natural effect of the floor vortices before they had the slots. The had little strakes and the like.

We see here with Mercedes' stuggles, that the slots allowed them to energize the flow into the diffuser by (I am estimating) creating really tight vortices (smaller radius) that fit under their low rear ride height even when cornering. Now without the slots it is harder for them to make those tight vortices. The high rake cars have more space under the floor so larger vortices will still work to seal, clean up tyre squirt and sweep in any emergy.

[FDD]

It's interesting, the only part in testing and also today in FP1 where they put some flow-viz on is on the rear-suspension:
https://pbs.twimg.com/media/ExZ2zb6XMAE ... name=large

I think I understand how the slots worked last year. They were guiding air to the low pressure region of the tire, equalizing the pressure with the higher pressure region above the floor where the air was hitting it. By reducing the pressure differential of the high and low pressure regions of the tire, it reduced the turbulence being shed by the tire.

This year I see teams trying to create high pressure region along the edge of the floor, but won't this just feed the low pressure tire squirt? Because upstream the car is shedding vortecies that are smacking into the rear tires.

From our understanding of combustion engines, we understand that swirl and turbulence both aid mixing of air and fuel, however it's not just limited to mixing air and fuel, it's also true about mixing airflows, particularly airflows of different temperatures. Like the different temperatures found in the brakes and tires relative to ambient airflow.

There are two ways to reduce tire squirt, or turbulence shed from the tire, you either lower the high pressure zone, or raise the pressure in the low pressure zone. You can change the pressure by adding heat, however adding heat also adds kinematic viscosity to air, and thus causes more skin friction on any surface, which will affect how air flows upstream. As the airflow will always migrate towards the lowest pressure it can find.

Maybe lower rake cars create more powerful tire squirt, while higher rake cars with greater distance from the floor, and closer proximity to the high pressure zone of the rear tire create a lower pressure differential in that region.

It's a shame the regulations don't let you turn the floor downward near the rear tires. All the teams want to flick the air up, but why not down, wouldn't that increase the pressure in the low pressure region of the floor weakening the turbulence being shed by the tire? It would also match the rotation of the vortex being shed by the diffuser.

The high pressure region already exists in front of the tyre. It's basically an air dam as the air hits this big blunt forward spining object head on.
The flow from it interferes with the edge of diffuser. Also the spinning and deforming wheel makes it worse.

Keep in mind, floor slots are a recent invention. If I remember the floor slots were seen first on a Ferrari after holes in the side pods were banned, Ferrari cut slits to keep "holes" for the exhaust gills on the side pod. Then this same trick was used to make "holes" then to be slots in the edge of the floor after exhasust blown diffusers were banned. If I remember correctly!

But anyway.. The floors managed to acheive a natural effect of the floor vortices before they had the slots. The had little strakes and the like.

We see here with Mercedes' stuggles, that the slots allowed them to energize the flow into the diffuser by (I am estimating) creating really tight vortices (smaller radius) that fit under their low rear ride height even when cornering. Now without the slots it is harder for them to make those tight vortices. The high rake cars have more space under the floor so larger vortices will still work to seal, clean up tyre squirt and sweep in any emergy.

"Keep in mind, floor slots are a recent invention. If I remember the floor slots were seen first on a Ferrari after holes in the side pods were banned, Ferrari cut slits to keep "holes" for the exhaust gills on the side pod. Then this same trick was used to make "holes" then to be slots in the edge of the floor after exhasust blown diffusers were banned. If I remember correctly!"
About side pods slits, yes Ferrari did that, I also remember. I think for the first time in 2007
https://torquepress.com/2018/07/classic ... rari-f2007

[Just_a_fan]

"Keep in mind, floor slots are a recent invention. If I remember the floor slots were seen first on a Ferrari after holes in the side pods were banned, Ferrari cut slits to keep "holes" for the exhaust gills on the side pod. Then this same trick was used to make "holes" then to be slots in the edge of the floor after exhasust blown diffusers were banned. If I remember correctly!"

About side pods slits, yes Ferrari did that, I also remember. I think for the first time in 2007
https://torquepress.com/2018/07/classic ... rari-f2007

Renault ran slits in the bodywork on the R26 in 2006.

[aral]

Could you please discuss this on the aero thread as it is nor RB16B specific.