How would anti dive geometry affect aerodynamic load under braking

[PhF1x]

With more teams expected to adopt anti dive geometries into their F1 cars next year I'm trying to gain a better understanding than I'm constantly seeing in other places which is "anti dive reduces pitching under braking and increases the chance of lockups".

With regular suspension geometries, under braking I can picture downforce initially going up slightly when the car pitches forwards as the wings would now have higher angles of attack relative to the airflow compared to with anti dive. Is this a noticeable effect?

With the current cars, if it pitches forward would be a greater loss in downforce than what is gained from the wings increasing their angle of attack?

Was Aston Martin's early season braking performance just down to the way the brakes are setup and sheer downforce or is there something more at play?

Lastly, for those who have worked with anti dive geometries, what are some ways to improve braking performance and braking feel?

[SangakaraMoory]

here is an overview of the questions you raised:

Anti-dive and Brake Lockup: Anti-dive suspension geometries are designed to reduce the amount of pitching (nose diving) that occurs under braking. This can be beneficial for handling stability, but it can also come at the expense of brake feel and lockup potential.
When a car pitches forward under braking, the front wings move to a higher angle of attack, which increases downforce. However, this also increases the risk of lockup, as the brakes are working against a more significant weight transfer.

Theoretical Downforce Loss: The theoretical downforce loss due to anti-dive is relatively small, as the increase in wing angle of attack is offset by the reduction in weight transfer. However, in practice, the loss of weight transfer can have a more significant impact on braking performance.

Aston Martin's Early Season Braking Performance: Aston Martin's early season braking performance was exceptional, and it is likely that a combination of factors contributed to this. Their car was well-balanced and had a lot of downforce, which helped them to maintain grip under braking. They also had a good understanding of their brakes and were able to optimize their settings.

Improving Braking Performance with Anti-Dive: There are a number of ways to improve braking performance with anti-dive suspensions. These include:

Optimizing brake balance: Brake balance is the distribution of braking force between the front and rear wheels. A well-balanced brake setup will help to prevent the car from pitching excessively under braking.

Using high-performance brake pads: High-performance brake pads provide more grip and can help to prevent lockup.

Optimizing brake temperatures: Brake temperatures play a critical role in braking performance. Brakes that are too cold will not provide enough grip, while brakes that are too hot will be more prone to fade and lockup.

Using a good brake management system: A brake management system can help to prevent lockup by monitoring brake temperatures and adjusting brake pressure accordingly.

I hope this information is helpful.

[Tommy Cookers]

'weight transfer' (mechanical not aerodynamic) due to deceleration is essentially the same with or without anti-dive

the first car with AD (Lotus 72) was intended to have aero DF distribution unchanged by deceleration
then they found laptimes benefited strongly from aero DF distribution changing strongly with pitch (wrote Peter Warr)

[Greg Locock]

Indeed, the weight transfer is purely related to wheelbase and cg location, nothing else. Because physics.

[Zynerji]

Indeed, the weight transfer is purely related to wheelbase and cg location, nothing else. Because physics.

CG location on the mass centroid?

[Greg Locock]

Not too sure what you mean by that. Draw an FBD.

[mzivtins]

Braking feel: Things like Toe/Camber changes will give a more variance of feel, but generally braking feel is only relative to pedal feel which is purely down to the hydraulics and pad-push-back forces.

When braking centering-torque forces across the steering axle are greatly reduced giving a sense of loss of feel through the wheel, the car will feel like the steering becomes more vague in straight line braking.

Going to make a sin here and declare an absolute: All race cars are pitch sensitive.
The change of angle of attacked is less of a force than the change of ride-height on leading edges due to lift/dive

Most (All?) wings and aero surfaces do must of their work in the underside and the closer to the floor any wing gets its effectiveness increases.

This issue with pitch is that you don't really want a change in aero posture giving you a car that does not have a consistent balance.

Good driver will use the pitch and weight to their advantage, you may pitch the nose down to increase grip on turn in, but then you have to immediately use throttle input to settle the car back to its optimum posture to then drive the rest of the turn.

In high downforce cars, this is impossible to do for most mere humans.

I think i have gone on too much, essentially anti dive/squat systems are there to give more consistency to the behaviour of a car throughout it dynamics range

[ing.]

With more teams expected to adopt anti dive geometries into their F1 cars next year I'm trying to gain a better understanding than I'm constantly seeing in other places which is "anti dive reduces pitching under braking and increases the chance of lockups".

With regular suspension geometries, under braking I can picture downforce initially going up slightly when the car pitches forwards as the wings would now have higher angles of attack relative to the airflow compared to with anti dive. Is this a noticeable effect?

With the current cars, if it pitches forward would be a greater loss in downforce than what is gained from the wings increasing their angle of attack?

Was Aston Martin's early season braking performance just down to the way the brakes are setup and sheer downforce or is there something more at play?

Lastly, for those who have worked with anti dive geometries, what are some ways to improve braking performance and braking feel?

Inclined wishbones does not indicate more anti-dive... just inclined wishbones mostly for aero:

viewtopic.php?p=1185542#p1185542

[Espresso]

....
Was Aston Martin's early season braking performance just down to the way the brakes are setup and sheer downforce or is there something more at play?
...

The dynamics and focus has changed.
The downforce created by the wings isn´t the most important anymore.
So the approach has to change towards the floor as main element (as intended by the regulations)

Focus on the floor. You want to keep the floor working optimal.
So keep it horizontal and at the optimal height.
So any movement of the floor needs to be vertical only at best.
So the focus of the (change in) suspension is to prevent the car diving and/or rising -and- getting to low (to low=stall=porpoising)

[vorticism]

Indeed, the weight transfer is purely related to wheelbase and cg location, nothing else. Because physics.

Yes, and perfect traction & brakes would send even an F1 car into a stoppie. One way to prevent that would be an infinitely long wheelbase and not even these cars will be approaching that anytime soon.

There seems to be some confusion about what anti-dive means; some are conflating it with the elimination of weight transfer, some are saying anti-dive doesn't even exist. It's a modification of the vertical acceleration profile seen by the front axle, as I understand it. Which is to say, peak load on the front axle during braking will be roughly similar amongst the cars, and suspension geometry like anti-dive can fine tune how quickly or slowly the front axle arrives at that value via suspension travel.

I imagine the effect even for RB is relatively small, which is why in the previous two seasons I couldn't easily say if it was an aero or kinematics decision. Usually safe to assume aero in this domain.

[AR3-GP]

In truth, anti-dive does have a small effect on weight transfer. Weight transfer is a function of accelerations and CoG height. CoG height is a function of anti-dive and the suspension settings. It's a dynamic system. The variables are coupled.

[Greg Locock]

Draw a free body diagram for the whole vehicle. Nothing other than wheelbase mass, gravity, longacc cgx and cgz is involved.

Because physics.

It may be that cgz is altered as the vehicle brakes, but the relationship is still there