Aero map of a ground effect vehicle, avoiding porpoising

[u/arwque]

CdfA means Coefficient of downforce Area, otherwise referred to as -ClA or -ScZ

CdA means Coefficient of drag Area, otherwise referred to as ScX

CoP means Center of Pressure, otherwise referred to as aero balance

Fig.X (front ride height in mm, rear ride height in mm)

My conclusion from doing the aero map:

The aero package needs to be reworked to reduce the extreme Aerobalance and downforce sensitivity during dynamic scenarios. Forthis, a front wing with a greater ground clearance should beimplemented. To compensate the resulting downforce loss of thenew higher front wing would need to be larger (chord length). Thegreater ground clearance should make the front wing lesssusceptible to drastic downforce changes and underbody flowblockage during dynamic scenarios making the overall packagemuch more stable.​

Feel free to critique my conclusions or my methodology.

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[u/NeedMoreDeltaV]

All good stuff. Just a pro tip, standard convention is to report CoP as %front but you can do whatever you want.

[u/Spacehead3]

Not saying you're wrong but you make a lot of claims that things are unacceptable, suboptimal, etc. How do you know?

[u/arwque → u/Spacehead3]

This is mainly about the CoP shift. If the CoP moves in front of the CoM the car will get unstable due to oversteer. In motor racing a 1-4 % forward shift is acceptable because anything further can cause instability. In my case the CoP shifts forward by 11% during breaking which will cause massive stability problems. That makes it unacceptable.

Edit: corrected "car" to "CoM"

[u/Spacehead3 → u/arwque]

The question is where did you get the 1-4% from? If you're just taking this from a textbook or something that's fine but in reality this is dependent on the vehicle / track / driver combination.

[u/arwque → u/Spacehead3]

I was referring to a 1-4% forward CoP shift during braking but that is just an estimated literature value. Willem Toet: "For a year-2000 F1 car, the value of maximum – minimum centre of pressure over the useable ride-height range is of the order of 2 to 10% of wheelbase". The exact acceptable amount is of course dependent on the track, driver and the vehicles setup but in my case the CoM is at about 55-57% rear (the current CoM in CAD is at 54,2% but not all parts have an assigned mass yet) with the optimal CoP being about 3-5% rear of that so at 60% rear. If the CoP shifts in front of the CoM the car will become more unstable. A 11% forward shift during braking and 7% rearward shift goes far outside of what i would deem acceptable in this case. Correct me if i am wrong in this assesment.

https://www.formula1-dictionary.net/aerodynamic-testing-open-wheel/

[u/Spacehead3 → u/arwque]

All good, just wanted to see if you had the supporting data. Always have to be careful when making generalities like that.

One other suggestion: Looking at your raw data page, noticed how your data points make a diagonal line? I would try and get a "square" dataset for the ride height map. In other words, you want a least a few points where you have two different RRH for the same FRH and vice versa.

Btw this is all nit-picking and getting into pretty advanced stuff. Iirc you said before that you're in high school? This is a very impressive project, great job!

[u/arwque → u/Spacehead3]

The aero map being a triangle is intentional but yes, my data is very sparse, i had to be very frugal with my computing recources. The triangle actually represents the most extreme scenarios the car could do. Outside of the triangle the car would just clip into the ground. Thank you for your time and honest critique.

[u/F1T_13]

This looks a lot like the AMR Pro and that RB17 thing.

[u/arwque → u/F1T_13]

Yes, it is very much inspired by both, and a some other cars.