How Porsche's Active Aero Works on the New 911 Turbo S

© Porsche

By Robin Warner, Autoweek

In Mark Vaughn’s recent drive of the 2021 Porsche 911 Turbo S, he briefly wrote of an updated feature on the car called Porsche Active Aerodynamics, or PAA. The technology and reasons behind it proved worthy of a deeper dive. PAA consists of three main parts: cooling air flaps, front spoiler, rear wing. Thanks to PAA, the 2021 Porsche 911 Turbo S creates a maximum 375 pounds of downforce at top speed, which isn't much compared to race cars, but quite impressive otherwise. It's also 15% more than what the last generation Turbo S could manage. Yet, the same car can switch modes and keep its coefficient of drag down to 0.33. That's high compared to a standard family car, but not much so for a high-end sports car.

To learn more about how PAA works, Porsche provided the following images to help visualize how the 911 Turbo S manipulates the air around it for improved performance.

Continuously adjustable air flaps

© Porsche

Let's start at the front with the continuously adjustable air flaps. They're highlighted in yellow in this illustration. When closed, more air travels around the bumper, which causes less drag, making it more efficient. The computer is programmed to keep the flaps closed as much as possible at 43 mph and above. However, they begin to open again at speeds above 93 mph for high-speed stability.

Downforce is created

© Porsche

When the air flaps open, cooling air gets to the brakes, and a bit of front downforce is created. These flaps remain open in sport and sport-plus driving modes for this reason—as well as when the driver either turns off stability control or turns on the rear spoiler.

Front spoiler

© Porsche

Next, let's check out the front spoiler beneath the air flaps—while it looks like a fixed piece on the 2021 Turbo S, it's actually built from a flexible piece of plastic that bends into different positions, depending on the demands placed on the car. This is its fully retracted mode (also known as basic), again, the most efficient.

Two additional settings

© Porsche

However, with two additional settings, the plastic extends toward the ground to generate downforce on the front axle. In speed mode, the outer parts of the spoiler extend like this, but the middle part of the spoiler stays in a more retracted position. This is enough to reduce front lift for high-speed stability.

Third position

© Porsche

In the third position, performance, the entire front spoiler extends into position to maximize downforce; this will almost certainly include the air flaps remaining open, as that also helps generate downforce, as well as keep the brakes cool. Again, this is ultimately controlled by a computer system making different decisions based on the driver mode chosen and other factors.

The rear wing

© Porsche

Moving to the back, the rear wing is 440 grams (or about 1 pound) lighter than the last generation Porsche 911 Turbo S' wing, yet it offers an 8% larger effective wing area and has several positions to choose from. There are three main levels to visualize. In eco mode, seen here, the wing is fully retracted, to minimize drag.

The middle position

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This is the middle position, also known as speed. The secondary wing is extended but not aggressively pitched. This gives high-speed stability without sacrificing much in top speed capability. This is the position for speeds above 160 mph. The wet mode position looks similar to this.

Performance position

© Porsche

The performance position is the most aggressive in this, its highest position, with its most aggressive pitch. This is the track attack, maximum downforce position of the wing. It also looks cool.

Air brake function

© Porsche

One neat trick of PAA is the air brake function under heavy braking at high speeds. In this scenario, all the PAA systems will be automatically placed in the highest drag setting to give the brakes a little help from the air to slow the car down and keep it stable. You can also see from this illustration how air generally flows around the 2021 Porsche 911 Turbo S.

Cool intake

© Porsche

From the back, cool intake air feeds into the engine from beneath the rear wing. Hot air gets extracted from openings on either side and beneath the dual exhaust tailpipes.

Adding more needed air

© Porsche

Finally, cool air finds its way to the engine compartment from just ahead of the rear wheels, adding more needed air to keep the engine happily making all 640 hp.

See more at: Autoweek