2022-2026-style Rear Wing CFD simulations

[Tzk]

I can’t think of a reason a team like Mercedes didn’t arrive at the same conclusion and still they went with the L shape. There must be a good reason why they still stick to L shape wings.

Maybe the interaction with the Diffusor, beam wing and the bodywork?

[G-raph]

Nice one, great to see that kind of CFD study.

Regarding the "including the endplate forces or not" debate, there are valid points on both sides but it would be interesting to report the L and L/D numbers with and without the endplates so we can all learn how much of a difference it makes. As they are the same design for all mainplanes it should be a fair comparison.

An honest question, is anyone really surprised RB was the first to figure out U wing is the optimal shape for higher downforce levels?

I'd say let's wait until Monaco before making such a leap.
RB19's high downforce RW was scoop shape, not U-shape. Scoop shape should still offer more total downforce (at reduced efficiency as you have shown) if all sections are properly optmised around the abrubt transition.

[Vanja #66]

I can’t think of a reason a team like Mercedes didn’t arrive at the same conclusion and still they went with the L shape. There must be a good reason why they still stick to L shape wings.

Maybe the interaction with the Diffusor, beam wing and the bodywork?

Can't say I know for sure, but these curved spanwise shapes weren't present in 2022, while Mercedes introduced their mid-level wing in early 2023. Most likely they didn't want to spend too much CFD and WT resources optimising wing design between seasns, when the rest of their car was in need of a lot more attention.

Nice one, great to see that kind of CFD study.

Regarding the "including the endplate forces or not" debate, there are valid points on both sides but it would be interesting to report the L and L/D numbers with and without the endplates so we can all learn how much of a difference it makes. As they are the same design for all mainplanes it should be a fair comparison.

An honest question, is anyone really surprised RB was the first to figure out U wing is the optimal shape for higher downforce levels?

I'd say let's wait until Monaco before making such a leap.
RB19's high downforce RW was scoop shape, not U-shape. Scoop shape should still offer more total downforce (at reduced efficiency as you have shown) if all sections are properly optmised around the abrubt transition.

Endplates generate about 100N of lift in total in every simulation. They are quite thin in my model, much thinner than reality, so they would only do their primary function of pressure field preservation on the underside. So they skew the lift figures a lot and then different drag figures for each design give a bit different skew levels of L/D ratio. I'm certain endplates on cars, being optimised to near perfection, have very different effect on entire rear end performance.

As for RB wings, Monaco 2023 wing was their 2022 high-level design. In reality, you can't really introduce a lot of curvature when you extend the maximum allowed cross-section height all the way towards the endplates. I was referring to medium and low-level wings regarding the U shape (and I should have made that clear ), which are used a lot more often.

[SiLo]

Sorry to have delayed this post a bit, but we are here now. With the reduction in tip foil thickness, there are now clear differences between different designs - both visual and numerical:

Scoop: -L=1695 N, D=368 N, L/D=4.61
U: -L=1708 N, D=364 N, L/D=4.69
V: -L=1625 N, D=339 N, L/D=4.80

All wings lost downforce of course, but Scoop wing also lost a bit of efficiency, while U and V wings improved. V wing remains the most efficient design, while U design generates the most downforce - even though the Scoop wing has the biggest frontal area.

The reason behind Scoop wing poor performance is an abrupt transition between the central section and the transition inclined surface. Here the suction zones get a bit broken up and this weakens them. I suspect this effect is even more pronounced on Mercedes/McLaren mid-high-level wings.

Although we didn't catch the effect of the tip vortex on the flap tip, there's now a bigger local curvature which causes the suction zone to spread diagonally across the wing - from the central belly to the rear of the tips. I suspect this might not be too far from what's actually going on, but impossible to say.

Next up will be 5 and 10 deg yaw simulations and I'm really looking forward to seeing what happens there!

https://i.ibb.co/cgdCY4k/comparison-v2-1.jpg

https://i.ibb.co/pnrpWFk/comparison-v2-2.jpg

https://i.ibb.co/D1Mzjmw/scoop-v2-5.jpg

https://i.ibb.co/bJKjsTC/U-v2-5.jpg

https://i.ibb.co/yy1N61n/V-v2-5.jpg

An honest question, is anyone really surprised RB was the first to figure out U wing is the optimal shape for higher downforce levels?

Interesting that the centre of pressure on the wings shifts backwards from Scoop, to U to V. It's farther back on the main plane.

[Vanja #66]

Interesting that the centre of pressure on the wings shifts backwards from Scoop, to U to V. It's farther back on the main plane.

Yes, it's because of the local suction peak on flap tips. With different foil design, it would look different of course

[SiLo]

Interesting that the centre of pressure on the wings shifts backwards from Scoop, to U to V. It's farther back on the main plane.

Yes, it's because of the local suction peak on flap tips. With different foil design, it would look different of course

Can you explain this in more laymans terms (or with a diagram) please? I am only a simpleton.

[Vanja #66]

Can you explain this in more laymans terms (or with a diagram) please? I am only a simpleton.

Red is the illustration of camber in the symmetry plane and blue is the chamber of wing tips. The curvature "peak" is also the suction peak and this moves from the point of main element maximum thickness to the point of flap interaction at the tips. This is a bit of a compromise from my side with the design, but I think it might be illustrative of the influence the tip vortex on the flap tip makes, generating suction peak with the vortex core as vortices usually do

[Stu]

Can you explain this in more laymans terms (or with a diagram) please? I am only a simpleton.

https://i.ibb.co/fFWg1cX/RW-chords.jpg

Red is the illustration of camber in the symmetry plane and blue is the chamber of wing tips. The curvature "peak" is also the suction peak and this moves from the point of main element maximum thickness to the point of flap interaction at the tips. This is a bit of a compromise from my side with the design, but I think it might be illustrative of the influence the tip vortex on the flap tip makes, generating suction peak with the vortex core as vortices usually do

Thank you for that illustration Vanja.
Not sure whether I am seeing this correctly, but not only does the more cambered wing create more drag, but the downforce also operates through a shorter lever length in relation to the rear axle (reducing the load on the rear axle)?

[Vanja #66]

Thank you for that illustration Vanja.
Not sure whether I am seeing this correctly, but not only does the more cambered wing create more drag, but the downforce also operates through a shorter lever length in relation to the rear axle (reducing the load on the rear axle)?

As usual, it can be better to keep forces and torques separated

Slight changes in rear wing CoP X (longitudinal) position do not have major effect on overall load of the rear axle. The whole car always works as a single aerodynamic body and generates one force with 3 projections and usually some torque around CoG of the car with nose-up pitch (ie the CoP is behind CoG). Typically, the flex of front wing flaps (and reduction of FW downforce) has bigger influence on increasing rear load at speed than some small changes in RW CoP can have

[CaribouBread]

Regarding different rear wing philosophies, we've seen Red Bull use a larger DRS flap to create their DRS advantage for a few years now. Why are other teams reluctant to head down this route? For example, Mclaren still has a very inefficient DRS. Is there any drawback to using this larger DRS flap during non-DRS'd situations? Or is it simply a budget/cost thing - to redesign their wings.

[Vanja #66]

Regarding different rear wing philosophies, we've seen Red Bull use a larger DRS flap to create their DRS advantage for a few years now. Why are other teams reluctant to head down this route? For example, Mclaren still has a very inefficient DRS. Is there any drawback to using this larger DRS flap during non-DRS'd situations? Or is it simply a budget/cost thing - to redesign their wings.

Ferrari has shifted slightly in this direction with the new mid-level wing, with Sainz achieving same Top Speed figures as Max in Q. In the race, Max was often harvesting more aggressively for some reason, so typically Sainz was reaching higher figures for that reason. In Jeddah, Ferrari was using too big a wing and are therefore incomparable to RB on Top Speed.

Why other teams don't do that, I guess it's mostly about cost saving and using existing Rear Wings as much as possible. Especially since no team other than RB and Ferrari (with a break during most of the 2023) showed it fully understands how to design and operate these cars and floors on the limit, so you'd have to imagine they find using most of their resources on the floor and suspension integration more beneficial than redesigning rear wing.

[variante]

Regarding different rear wing philosophies, we've seen Red Bull use a larger DRS flap to create their DRS advantage for a few years now. Why are other teams reluctant to head down this route? For example, Mclaren still has a very inefficient DRS. Is there any drawback to using this larger DRS flap during non-DRS'd situations? Or is it simply a budget/cost thing - to redesign their wings.

Because a shorter flap normally means more downforce. So, you're going to get more performance every time you're not using DRS.
That's because flow separation tends to happen toward the trailing edge of the wing, so you want your flap slot to be placed there, not much forward.

So, the real question is: how are RedBull getting away with such a large flap?

[FDD]

"Scoop: -L=1805 N, D=390 N, L/D=4.63
U: -L=1820 N, D=392 N, L/D=4.64
V: -L=1750 N, D=368 N, L/D=4.76"

"-L" means negative lift?