Dr Obbs Profile picture
May 25, 2023 10 tweets 5 min read Read on X
Ok so I had questions like many about the legality of the new @MercedesAMGF1 #W14b spec floor winglet. With the help of some friends, I did a bit of digging into the regulations to understand this better. A 🧵@Formula_Nerds @AlbertFabrega Photo by Auto Motor Und Sport
The regulation boxes are sometimes super confusing so it's best to start with an overview of them. The below link is a good place to start to understand the regulation boxes where engineers can design within. Each reg box is controlled differently. 🧵racecar-engineering.com/articles/tech-…
So after looking at the reg boxes, these aero features can only be in these potential volumes, Front Chassis, Mid Chassis, Floor body, Floor fence, or Rear Body Work Sidepod. So now lets eliminate them 1 by 1. First it can't be fence, because these aren't floor fences 🧵 Image
It can't be floor body, because surely they have maximized the regulation volume for the floor and did not sacrifice this critical area for a few flick-ups. And the canard is no way in this volume. So what about RBW SidePod? 🧵 Image
Looking at the regulations, it would have to be pretty far outboard to be in the sidepod volume, and this is a heavily regulated region as well. Heavy radius regulations that these would violate. So couldn't be this. 🧵 ImageImage
Only thing left is the Front and Mid chassis volumes. Looking in Issue 6 of the 2023 technical regulations, you can see there are some convexity and concavity controls in the forward chassis, but in the mid? Virtually nothing! It just has to fit in the reg box! ImageImage
So asking around, it seems that this is the same regulation box that is allowing teams to use winglets around the cockpit to manage cockpit losses. So pretty much anything is fair game as long as it fits in the regulation box. So how do these on the Merc fit? 🧵 Image
Well, if you were to sacrifice a bit of your chassis front and mid volumes to create a slim no-pod type design, then you would be left with some volume to create canards and winglets! It's an open reg box to include these features, and this is how I believe these are legal. 🧵 Image
The only downside, is that you can't extend these further out and away from the body towards the floor edge. You can see this when you observe just how close the winglet is to the chassis bodywork. 🧵 Image
So according to my review, this new winglet, like the canard, is legal. How much they help, is unknown to anyone who doesn't have the CFD. But there must be some gains for them to have them there. Thanks to my "nameless" helpers, and I hope you enjoyed this explainer thread! Image

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More from @dr_obbs

May 28
Lots of talk about tyre degradation, tyre temps, balance, and the like. So I think it's time for a refresher course on tyres, grip, and degradation. I'll try and cover all of this in this thread, but stay at a high level (because it's incredibly complex) for general understanding.

Firstly, we should understand that as a car goes around a corner, the input angle of the driver to move the tyre relative to the direction of travel creates a slip angle. This slip angle creates the forces at the contact patch that act to rotate the car about the Center of Gravity (CoG) through the corner (moment).Image
If we focus in on a single tyre, then we see that with increasing slip angle (with constant Normal Force), the lateral force to turn the car is increasing until a limit (sliding limit). After this point, increasing slip angle will result in less lateral force, as the tyre is no longer able to impart a force at the contact patch without sliding.

The rubber tyre behavior plays a key role in this as well. In the initial stressed region, the rubber acts as a linear elastic material with increasing slip angle (Figure in the middle). At a point, this transitions to an intermediate phase where the rubber acts non-linearly. This non-linear stress response generates a hysteresis within the material that manifests itself in a heating response. This is termed hysteretic heating, and can be a key to generating bulk tyre temperatures.Image
The grip at the contact patch is greater as the load at the patch is increased. This means that the lateral force that can be generated from the same tyre is greatly increased with increasing normal force. This is why downforce for race cars matters so much. As you increase the load, the turning force that can be applied is increased, as well as the load limit for sliding at increasing slip angle. The coefficient of friction between the track surface and the rubber plays a key element in this as well. With different track types, the surface has more or less grip potential. Essentially more or less coefficient of friction.

Ref. image (suspensionsecrets.co.uk/tyre-slip-angl…)Image
Read 8 tweets
Mar 13, 2024
People often ask me, "where can I find great information on motorsports and aerodynamics?" So how about a thread of some of my favorites? And no, I don't get paid to endorse these. I just think F1 Tech is a great place to share knowledge! Also, this is NOT an exhaustive list, but some that stick out to me. Feel free to add yours as well below!

Video below by Vyssion and JJN.
Let's start with some of my favorite books on car aerodynamics! "Race Car Aerodynamics: Designing for Speed" by Joseph Katz is goated. A really great book covering all types of race cars and written for anyone at any level. I highly recommend this book. Image
Another book that is sort of an extension of Katz is one from Simon McBeath called "Competition Car Aerodynamics." It's like a newer version of Katz book, and with a bit of very simple CFD in it as well. Image
Read 17 tweets
Mar 4, 2024
Is the RB20 great? Or is Max Verstappen + the RB20 great? I spent some of the weekend looking through the telemetry. And here is what I have found. In summary, Max Verstappen is a Swiss f*cking watch. Well, maybe a Dutch watch. Let's look at it in this thread. Image
Looking at the macro view level lap times to gage consistency, you can see that it's incredibly consistent irrespective of compoud. Credit to Checo as well, his lap times in Bahrain were also very consistent, but also consistently 5-tenths to 1 second slower per lap. But why? Image
Looking over the a single lap, many show similar characteristics. It's like death by a thousand paper cuts, or in this case by 15 corners. The intricacy and precision of driving from one corner to the next builds delta from corner to corner. Image
Read 13 tweets
Jul 12, 2023
Was the RB19 of MV really slow on the straights compared to the other teams? Or was something else going on? We know that MV wasn't fortunate to gain any DRS or slipstream after passing LN, but what else was going on? Let's understand this more in the thread below. 🧵
If we look first at the pit straight into Turns 1 and 2, comparing LN and MV, we see something peculiar. MV never upshifts to 8th gear, but holds 7th. Thus, his engine RPM is higher and he doesn't lift into T1. He does, however, lose time slightly to LN due to the lower speed. 🧵
Looking at the onboards, LN is 1.336s behind MV so he may catch a very slight tow, but the top speed delta here is 4kph with LN reaching 300kph. By MV never upshifting to 8th gear he limits his T1 entry speed, but doesn't have to lift as a result. 🧵
Read 11 tweets
May 31, 2023
Well that helps to solve that mystery. Had also heard that this plank was painted so they could observe the wear patterns better. Looking at this, the plank wear is quite low overall. How about a thread comparing my observations of the RB, Merc, and Ferrari wear patterns.🧵
The bib looks to be running quite low. Possibly some forward rake, as most suspect. RB is able to run their forward floor very low, and still ride curbs and manage bump tracks like Monaco. A bit more left sided mid wear. 🧵 Image
Mid floor looks pretty stable with little wear. Same preferential left side wear from previous image along the length of the mid floor. No floor flexing going on here. 😉 🧵 Image
Read 7 tweets
May 30, 2023
There is a quote in here that perfectly summarizes what I have been trying to say about the complexity seeing an image of a floor, and then getting a floor to work well.

"Talking to an engineer from the Milton Keynes team, not too worried about the photographs taken of their.."
"..underbody in Montecarlo, he explained to us that it is easier to work on the cross section of the channels while the slope (height) variation part inside is much more complicated to the tunnel and the simultaneous generation of eddies; an infinite job, among other things.."
".., since a car never works with a constant height but has many external elements, such as bumps, and dynamics, such as roll, pitch, etc., which greatly complicate the design of what it is the most important aerodynamic component of these new F1 cars..."
Read 4 tweets

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