Ferrari SF70H Sidepods - A Masterpiece, Part II

In previous article, Part I, I opened a discussion about interesting sidepod design of SF70H, Scuderia Ferrari's 2017 Formula 1 contender. I probably left some questions unanswered and I haven't provided any credible evidence to support my proposition. In this article I plan to do just that.

(R)evolutionary design

At first, you'd say that this is a revolutionary design by Ferrari, a clear step in a different direction compared to 2016 car. And yet, front wing is quite similar in design, as is the nose. There were some interesting aspects concerning SF16-H, none as SF70H's design though. For 2017, amongst other changes, angle between wishbone profiles on suspension arms is now allowed to be 10 degrees in relation to reference plane, compared to 5 degrees before. Ferrari have exploited this as well, but they have done so in 2016 as well.

Figure 1 - comparing suspension arms AoA, Ferrari in 2016 and 2017

Note that little vane above the tea trey on SF16, if I remember well people were thinking last year that the primary purpose of it is to start a vortex or enhance the Y250. Looking at what came afterwards, towards the end of the season:

Figure 2 - SF16-H detail

... you note that this element is now slotted and has it's own winglets basically. Winglets are used to minimize the vortices, right? So what if the main purpose of these parts was to guide the air down towards the floor? Sidepods on SF70H would then be an evolutionary step (a big step though) rather then revolutionary. Move the radiators a bit to the back and make them more compact, use bigger vanes to control the air in front of them, use the space gained to put an aggressive wing-like intake lip and make it work with all the extra space allowed by new rules for winglets and vanes. Sounds plausible... It's worth remembering that diffusers on 2017 F1 cars are now a lot bigger and more aggressive, creating bigger suction zones. Combined with bigger radius allowed for floor leading edge, they have the capacity to notably change some flow structures in front of the floor and perhaps even further away. All in all, I would call 2017 Ferrari F1 car design an aggressive evolution rather than a revolution. Hard to spot a difference sometimes, isn't it...

What about competition?

Still, I provide no evidence to support my ideas. Sadly, that's because Ferrari gave us none. In all 8 days of pre-season testing they haven't applied any flow-viz in this area. Not even once... And I have been looking out for those vigorously! Sadly for us, even more so for their competition. They did use aero rakes with Pitot tubes a lot, but that's not really helpful for anyone other than aero guys in Maranello. Does this mean they are confident in their design or don't want to give anything away to other teams? Probably both... With Mercedes being the closest competitors based on tests, and being the obvious team to beat this year, lets take a look at them.

Figure 3 - W08 and W07 detail

As Ferrari, Mercedes also used angled suspension arms in 2016 (not sure about 2015) and they don't seem to be changed that much in 2017. This shows that they try to bend the air downward also, but not as much and rely on other parts to achieve what they want.

Figure 4 - W08 sidepods, launch spec and first pre-season update

As for sidepods, Mercedes is keeping same philosophy as last year (originated on Ferrari 2015 car). They use inner part of the top intake lip to "encourage" air to go outboard more and so reduce the amount of air going over the sidepod. This reduces lift and guides the air to the side and towards the coke bottle zone more effectively. It is an evolutionary continuation of W07 design - if it works, don't try to repair it.

McLaren MCL32 is an interesting car as well, very sophisticated and elegantly simple. As with others, you only notice the details later, and there are some similarities to SF70H.

Figure 5 - MCL32 barge boards

Barge boards feature a wing-shaped bracket to the chassis, removing any possibility of vortices creating where they don't want them. Is this also used to guide the air down, towards the floor and around the sidepods?

Figure 6 - flow-viz contours around MCL32 barge boards

McLaren gave us the much wanted flow-viz info in this area! It seems that the air is indeed bent downwards coming towards the inlet, just like we presume for SF70H. Like I stated above, this is most likely a combination of many factors. Still, barge board itself isn't that similar to Ferrari, or is it?

Figure 7 - barge board pre-season evolution, MCL32

This leaves us with Red Bull RB13 to wrap up this little discussion. RB13 was a car eagerly anticipated, but the launch spec was incredibly simplistic and looked completely undeveloped. Again, only after a few days of testing you could notice a number of wonderful details and the philosophy of Adrian Newey showed itself once again. Unlike in 2016, RB13 features angled wishbone profiles like other top cars.

Figure 8 - RB12 and RB13 barge board area

Comparing SF16 and RB12 shows this difference in wishbone design even better, the ones on Ferrari appearing to be much thicker:

Figure 9 - comparison of 2016 cars

With hindsight, they weren't that thicker on Ferrari, rather they were angled. Some flow-viz Red Bull, please?

Figure 10 - flow-viz contours around RB13 suspension pick-up points

Just like on MCL32, air is going down and every little bit is used to help guide it where designers want it to. You can also notice those huge turning vanes on chassis in front of barge boards, they seem to keep the air under it separated from the outside air, probably even energizing the boundary layer with multiple slots.

Figure 11 - RB13 turning vanes

Conclusion

Sidepod design of Ferrari SF70H is very different from all others, but seems to be an evolution that other teams have followed in a similar fashion as well. As I said before, I'm certainly no expert in this area and I just wanted to give my opinion on this matter that has captured the attention of many others. With that said, I do have some early experience in aerodynamic design of open-wheel race cars in CFD and wind tunnel and wouldn't dare speculate on any of this purely on gut feeling.

Ferrari SF70H is designed more aggressively than all other cars in this area and seems like it made the next step in sidepod design. The pace (both in single lap and in race simulation) it has shown in pre-season testing is admirable and has turned many heads. For many years, Ferrari haven't made such a bald and innovative move in car design and they seem to be quietly confident with it. Since late 1960s radiators were put on the sides and intakes were facing the front. Could that be changed in 2018 with an evolution of Ferrari SF70 having intake openings only on the top of the sidepods? With Formula 1, you never know!

Thank you for taking your time to read this two-part article!

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