Red Bull RB18

[ScrewCaptain27]

Or it is just there to cope with compressive loads.

Any sort of internal bracing would provide the same effect. So then, why go through the trouble of making a unified arm? On the RB16B it did appear to be a continuous part.

https://i.imgur.com/abPYosC.jpg

I think the reason is quite simple: weight saving. If multiple parts don’t exist you can’t make them any lighter. It’s the same reason some mid-2000s cars adopted the same solution.

[vorticism]

I think the reason is quite simple: weight saving. If multiple parts don’t exist you can’t make them any lighter. It’s the same reason some mid-2000s cars adopted the same solution.

Makes sense, although with the keel you'd either have two rose joints right next to each other or you'd replace that with a continuous mass of CF and a clamping device, gaining some weight back. Similarly with this interpretation, omitting two ball/rose joints saves weight but you gain some back with the addition of the central spar and the scallop required by the chassis, and the anchoring/clamping devices/bushings. Others earlier were suggesting the leaf spring (maybe you as well?) explanation, which makes most sense to me.

[Airshifter]

Is there any way this arm can torque under particular loads changing wheel angles?

It seems to me they are using it as a leaf spring/anti roll application, and other than having influence on the opposite end, it shouldn't torque any other direction.

But with various mounting points and elements (springs) they could alter how much the opposite side wheel is influenced and use it very well as an anti roll measure.



In doing that, they can save weight in the other internal parts of the suspension, since the anti roll bar, heave springs, and torsion bar would be under less stress and as such can be made lighter.

[Henk_v]

Or it is just there to cope with compressive loads.

Any sort of internal bracing would provide the same effect. So then, why go through the trouble of making a unified arm? On the RB16B it did appear to be a continuous part.

https://i.imgur.com/abPYosC.jpg

Is that really what we see? I see a uniform member clearly in your picture,but in the RB18 case, it does not look particularly so. Any brace would do, but as it happens, pipes are the best for compressive loads as their buckling strength to weight ratio is highest.

[ScrewCaptain27]

Is there any way this arm can torque under particular loads changing wheel angles?

It seems to me they are using it as a leaf spring/anti roll application, and other than having influence on the opposite end, it shouldn't torque any other direction.

But with various mounting points and elements (springs) they could alter how much the opposite side wheel is influenced and use it very well as an anti roll measure.

https://upload.wikimedia.org/wikipedia/ ... _plane.JPG

In doing that, they can save weight in the other internal parts of the suspension, since the anti roll bar, heave springs, and torsion bar would be under less stress and as such can be made lighter.

Not sure this simulation is very accurate or representative of the actual solution found on the car. The suspension arm is obviously braced and fixed in place on the top and bottom, and has two flexure points as opposed to a single one. Not that it still can't function as a sort of leaf spring, but I doubt that the movement of one wheel has an influence on the other in this case.

[PhillipM]

Still looks just like a mounting tube to hold the wheel tethers to me.

[Big Tea]

Is there any way this arm can torque under particular loads changing wheel angles?

It seems to me they are using it as a leaf spring/anti roll application, and other than having influence on the opposite end, it shouldn't torque any other direction.

But with various mounting points and elements (springs) they could alter how much the opposite side wheel is influenced and use it very well as an anti roll measure.

https://upload.wikimedia.org/wikipedia/ ... _plane.JPG

In doing that, they can save weight in the other internal parts of the suspension, since the anti roll bar, heave springs, and torsion bar would be under less stress and as such can be made lighter.

Would that then alter the apparent length of the arm and angle the wheel? There does not seem to be anywhere a sliding or lengthening element could be?

[marcel171281]

Still looks just like a mounting tube to hold the wheel tethers to me.

They are supposed to be mounted to the chassis. So how do you explain the tether to be in this tube, going from one wheel to the other? That would mean the tethers are connecting the wheels together. And that would mean, in a violent crash, that the wheels won't stay on the car, but fly of together.

[PhillipM]

How could they? The tube is anchoring them to the chassis.

[Giando]

https://it.motorsport.com/f1/news/f1-re ... e/8602347/

about the upper single arm of the front suspension...

[vorticism]

Not sure this simulation is very accurate or representative of the actual solution found on the car. The suspension arm is obviously braced and fixed in place on the top and bottom, and has two flexure points as opposed to a single one. Not that it still can't function as a sort of leaf spring, but I doubt that the movement of one wheel has an influence on the other in this case.

Probably more scope for heave and corner forces if anything. Another thing to think about is where on the arm most of the pivoting would occur. It may arc along the entire length through travel, rather than pivot near the inboard attachment in the sense of what a typical ball joint would provide. This would alter the path of travel of the lower upright connection point; presumably yielding travel something more like a shorter lower a-arm.

[AR3-GP]

This is a kinematically constrained system due to the connection of the other 4 suspension elements to the upright. Therefore there should be very little to no forces causing the FUCA to move along it's axis.

For the bar to have any anti-roll capability, there must be some torsion exerted on the bar by the upright displacement. From the images we have currently, it does not appear that geometry would generate any twisting of the control arm due to wheel displacement. I do not believe this bar has any anti-roll capacity.

To me it just looks like the arm is used as a secondary spring medium. The calculations are only slightly more complex. Previously, you have just a tire stiffness, and a rocker spring stiffness. Now you have a tire stiffness, rocker spring stiffness, and FUCA stiffness.

[vorticism]

How could they? The tube is anchoring them to the chassis.

Depends on how the arm is anchored. On the RB16B photo (few posts back) the bar has no visible fasteners, just sits in a channel on pillows. Probable bolted through somewhere though. On the keeled cars, the arm still anchored their tethers separately, fwiw.

[chrisc90]

There could be a small hole to allow the tether to come out and mount? If its hollow already, theres no need for it to be a continuous tube with no holes. They could have a small 5-10mm sized hole for the wire to come out and mount to the chassis

[vorticism]

They only need three tethers per wheel, and they have typically four arm elements available for them to pass through. So in this case they could use the trailing halves of the A arms (2) and the leading edge of the lower A arm (1), and avoid the use of this supposed leaf spring all together. Also, regs state each tether must not "share a common fastener" so that may rule out the pass-through option (wheel to wheel, yet anchored in the middle would still entail a shared fastener).

The tethers have a minimum length rule and must keep a detached wheel from striking the driver. Now I'm wondering if that drives some of the A arm dimensions that we see. The diagonal brace might not be swept back as far as would be ideal structurally, in order to provide a shorter tether through those parts of the arm.