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Comment by sz4kerto | Hacker News Reader

"The original Roadster had a drag coefficient (Cd) of 0.36. Using modern computational methods we expect to make a 15% improvement, dropping the total Cd down to 0.31 with a retrofit aero kit."

I wonder how's this going to affect the generated downforce (=> and, as a consequence, the aerodynamic grip). Cd for a F1 car is around 1.

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'Cd is a coefficient. It reflects the aerodynamic efficiency of the car relative to an equivalent frontal area oriented vertically [i.e. a brick]. An F1 car achieves efficiency by having a small frontal area and effectively directing drag forces. 0,5 square meters with a 'Cd of 1.0 creates less force than 2.0 square meters with a 'Cd of 0.3.

Is aerodynamic grip really relevant for a road car? Is anyone really turning at a speed fast enough for it to matter? If you want to improve grip for your road car, you tune the suspension and buy some nice tires.

Lowering the Cd will definitely improve your milage, however.

Computional methods have improved that much in ten years?? Why aren't all cars doin this?

They do: even pedestrian looking Audis and Mazdas from a few years ago beat this retrofit by quite some margin. And the Tesla Model S is 0.24.

So what was it we couldn't do ten years ago to get these same values?

In the case of Tesla you mean? One look at the Lotus Elise and you'll see they weren't exactly going for aerodynamics. Tesla barely survived the launch, so it wasn't going to happen back then.

This is one of those "in hindsight" kind of things that never get fixed. The fact that Tesla is doing it says a LOT positive about them.

My Audi A6 has a Cd of 0.26. Comparing it to F1 makes no sense. They're open wheel.

It absolutely does make sense. F1 cars have high Cd because they need lots of downforce. An A6 does not need as high Cd as a sports car. So if a roadster's Cd goes down then the question arises: will it affect it's aerodynamic grip or not?

Since you're asking a math question the answer is "yes of course." However having owned an Elise and driven a Tesla Roadster I will confirm that strapping the equivalent in weight of an entire F1 car in batteries to the bottom of one removes aerodynamic handling from the bigger equation at play.

They're fun as hell and also uncomfortable as fuck. 400 miles is more of an endurance test for the driver than the power supply. (Also, loved every second inside both of them!)

Not only are they open wheel, but they have intentional downforce that exceeds the weight of the entire car.

They also have 600 horsepower and pass a gas station every 45 seconds :) Why compare?

Current F1 rules do not allow in-race refueling. But, yeah, expensive purpose-built race cars have little in common with road cars.

Ah, I was thinking of Indy.

> But, yeah, expensive purpose-built race cars have little in common with road cars

I wouldn't say little.

Many F1 technologies have made it into production road cars and the future of the sport will see this technology sharing increase. That's why there was the big engine change last year. And it wouldn't surprise me if their split turbocharger design that was responsible for Mercedes success makes it into their road cars.

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