Civetta Bolide AERODYNAMICS

Hello and welcome to an overview of the aerodynamic properties of the Civetta Bolide in BeamNG.drive.
In this quick post I will shine light on quirks of the Bolide platform and it's aerodynamics using the integrated aerodynamic debug tool.

!DISCLAIMERS!

1. English is not my first language so don't expect perfect punctuation or grammar. Please be respectful of the idea I want to send and ask if there's something unclear that I might have written weirdly.
2. I am NOT an aerodynamic expert, I haven't learned anything about aerodynamics. I'm just applying the "if it looks good, it will fly good" concept but to cars, and in reverse since cars shouldn't fly

With those out of the way lets get an overview of:
Civetta Bolide



The Civetta Bolide is a sports coupe that was produced between 1981 and 1988. It offered amazing technology for the time like pop up headlights or a wedge shape design, which we will dive into in the aerodynamic overview.

It was originally featured in a reveal trailer on youtube and it's between the oldest cars in the BeamNG universe.

The Bolide weighs about 1350-1400kg(3000-3080lbs) and offered three engine variants from the factory.
1st we got the 350 variants featuring 3.5L Naturally Aspirated V8 capable of about 260bhp and 315Nm of torque.

Being an 80s mid engine sports car it came with handling caveats, most notably lift-off oversteer. The lack of a spoiler on the lower end models doesn't help as the nose still creates a considerable amount of downforce even in these lower end models.

The Bolide also came in a bigger 3.9L V8, also Naturally Aspirated, which, contrary to the usual tred of displacement , it revved higher than the 3.5L, allowing it to hit a 323bhp ceiling with minimal torque increase(336Nm)

Lastly it, the 320 GTT variants included a revolutionary European design that started to form. The engine was made smaller, and to compensate for the lack of displacement, a twin turbo system was fitted to boost(0.9bar) the tiny engine to an amazing 396bhp and 495Nm of torque.
The smaller engine, along with suspension geometry improvements, greatly lowered the lift-off oversteer of the original models, but it wasn't gone.

Community wise it's loved by few, hated by many.
Its quirky handling makes it hard for lower skilled drivers to pick it up, making the Vivace Gravel rally with clockwise wheels and race tires the better choice.

AERODYNAMIC OVERVIEW

As previously mentioned, the Bolide offers an iconic wedge design, being inspired by the Lamborghini Countach, but with a rather more Ferrari-esque look

The wedge design was revolutionary for Lamborghini at the time because of the surprisingly low drag, which is what we also see in BeamNG

The pictures that are about to be attached were taken at 200km/h airspeed with 0km/h wind.

The aerodynamic model of the Civetta Bolide looks fine, at a first glance. Low drag allows the vehicle to hit high top speeds for the somewhat low horsepower of the 350 models(That is if you have the space to reach said speeds)

Most aerodynamic vectors look fine but there are outliers that raise curiosity (Genius emoji)

Let's analyze:
On the front side we can observe small lift created by the nose. It's far from a problem as it's highly shadowed by the downforce the nose creates

Most probable cause by a rapid separation between the upper and lower part of the airflow. The main culprit is the blunt nose of the Bolide that doesn't do much in terms of smooth air separation by today's standards. It is to be appreciated that the Bolide has a front radiator duct that does in fact need airflow. Overall a pretty good model for now.
Moving over to the mid section:

Now, considering how tall this image is... let's look into the big outliers on the right side of the image.

After a bit of looking around it seems to be caused by how triangles form on/with the steering column/part
Notably FX5R and FX5L are the biggest outliers in the image, becoming the biggest vectors in the whole aerodynamic model.

Now I am not here to claim it's wrong, this is the devs' job to confirm/deny/whatever they do.
What I can confirm is that the outliers disappear when I remove "Steering" from the parts list.

The roof is surprisingly clean, not generating much drag nor lift

The rear is another story.
We can observe that high lift starts being generated at the tailgate.
This would be fine but it is highly exaggerated, again by an outlier, this time a somewhat small one, considering the front.

This time the outlier node with the high lift is RX6
This seems to be a small trend of frame parts that would otherwise not impact the airflow, impacting.. well, the airflow. I have no idea if this is intentional or if it's a shortcoming of the aerodynamic simulation.

With this out of the way let's move over to the back side, probably the best from the aerodynamic standpoint.


We can observe high drag, yes, but that is normal for the hard end of the tail.

The lack of a small lip on the end makes the tail create more lift than it should, but it lowers drag so I count it as a choice.

As for downforce? Not a lot. The diffuser does create some downforce, but it's very barebones and it has no way to compete with the rear lift, considering the outlier.


From a symmetry and stability standpoint it's fine, but the front outliers create a slight sway to the left.(barely noticeable but creates instability)

The outliers(FX5L and FX5R) might be creating more lift on one side than the other, but not enough to completely destroy the general stability of the car.

The outliers don't create drag asymmetry, which keeps the car going straight.


The headlights seem to have more drag closed than open. I might be tripping, or the drag is applied somewhere else in some other way that I can't see, but looking at the headlights themselves the drag seems to lower.

They do create a slight downforce which is to be expected considering the AOA.

Opening them does make the downforce disappear, almost becoming lift.

The lift is slight but real, the drag on the other hand is nonexistent.


Overall I am pleased with the aerodynamic model of the Civetta Bolide and I am looking forward to learn if the outliers are in fact "outliers" or if there's something I'm missing.

Again, this post was made for everyone to learn and share their knowledge. I am open to suggestions, criticism and most importantly learning.

Setup: Grid map, default tire pressures, no environment modification. The config used is 350(m).
Drive straight until 200km/h airspeed.(preferable hit with coast throttle rather than accel then pause at 200)
Here's a quick table of the outliers if somebody wants to replicate the issue​

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FX5L – Front suspension / steering; large upward vector (~1.4–1.5× FX5R); likely extra/overlapping triangles or larger effective area.

FX5R – Front suspension / steering; large upward vector (baseline); smaller magnitude than FX5L.

RX6 – Rear frame / tailgate area; moderate upward vector; contributes to rear lift, possibly due to frame/coltri geometry.\

Quick reminder that I don't know how BeamNG's aero simulation actually works. My arguments are mainly built on assumptions and the little documentation I could find.

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If you reached the end, what car do you think I should do next?(Stick to vanilla cars please)
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