Porsche strikes right balance between drag and downforce

German sportscar maker Porsche’s focus on performance is the stuff of legend. It’s buyers know that and crave even more with every succeeding generation of their cars, especially the 911. No other car maker can get away with claimed light-weighting benefits by selling a road-legal model without something like a music system. Buyers don’t mind paying extra if need be because they are clear about their choice and are equally obsessed about performance.

Earlier this week Porsche put out official information about the new 911 Turbo S and Coupe. And a lot of attention has been lavished on the aerodynamic performance of the new model. Significant changes to the aero package is said to enable the 911 Turbo S to deliver a more agile and at the same time more efficient performance. Two of the issues that affect sportscar performance is the balance between improving aerodynamics and simultaneously ensuring high downforce. The German car maker has successfully mastered this mix with its Porsche Active Aerodynamics (PAA), which adapts the aerodynamic characteristics of the vehicle even more precisely to the driving situation, speed and selected driving mode. PAA was premiered in the previous generation of the 911 Turbo in 2014. All model lines from the 718 through to the Panamera and Taycan now feature active aero-dynamic elements.

The newly designed active front spoiler and rear wing have increased the downforce by 15 per cent to guarantee enhanced driving stability and dynamics at higher speeds. The drag coefficient (cd) of the 911 Turbo S varies depending on the aerodynamic setting. The most efficient configuration with the minimum cd value of 0.33 is achieved with closed flaps and retracted front and rear spoilers. There are a total of eight different aerodynamic configurations in the new 911 Turbo S, which are each described by a specific combination of the active aerodynamic components.

Adjustable air-flaps

The newly controlled cooling air flaps permit a lower driving resistance and thus reduced fuel consumption. The flaps are located in the right and left air intakes of the front apron; are continuously adjustable and control the cooling air throughput to the radiators. Porsche says that an intelligent energy management system is responsible for achieving a balance between the current cooling requirement, the electric power required to operate the radiator fan and the aerodynamic benefit of the cooling air flaps. As a result, the cooling air flaps are closed as far as possible from a driving speed of 70kmph. From a speed of 150kmph, the flaps open linearly to achieve the optimum aero-dynamic balance at high speed. Priority is also given to driving dynamics and the cooling air flaps are thus opened when the Sport, Sport Plus and Wet driving modes are active and when Porsche Stability Management (PSM) is deactivated or the spoiler button pressed.

Front spoiler

Porsche’s post unveil press release says that the active front spoiler of the 911 Turbo has been significantly enhanced. The effective aerodynamic area has been increased compared with the predecessor. Extension and retraction can now take place in a shorter time with lower pressure. Three segments can be inflated separately with the help of actuators. The two outer actuators always function synchronously. The front spoiler is made of a flexible plastic (elastomer) and can therefore be rotated so that the middle segment can be retracted or extended when the outer segments are extended. So, there are several adjustment possibilities, including for reducing the lift at the front axle at higher speeds.

Porsche claims that the lightweight construction used on the rear wing means it now weighs 440 grams less than the corresponding component of the predecessor, but has an eight per cent larger effective area. The basis of the wing is a foam core with forged inserts. The official statement says that the structure consists of an upper side with two layers of carbon-fibre re-inforced plastic and a lower side with one layer of glass-fibre reinforced plastic. Electric adjustment of the wing – which can be extended and tilted – is performed primarily depending on the speed and selected driving mode. Depending on the driving modes, there are now additional positions as well as the familiar Speed and Performance positions.

Wet mode and airbrake

Porsche has also highlighted a couple of new modes for additional safety. According to the company, with the new Wet mode, the focus is on driving stability in wet conditions. If the sensors equipped as standard in the front wheel housings detect a significantly wet road surface due to spray that is swirled up, a corresponding message is displayed to the driver in the instrument cluster. The driver can then manually activate Wet mode by means of a rotary switch on the steering wheel. In addition to the adaptation of the aerodynamic components, all relevant control systems are also set to maximum driving stability.

The new airbrake function is activated automatically in the event of full braking at high speeds. The front spoiler and rear wing are then moved to the Performance position. The higher drag and increased downforce can reduce the braking distance. Driving stability is also improved during braking.