Sunday, March 2, 2014

Finally, Flying Car Mode

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A flying car is one of the evergreen fantasies of car guys, and finally Chevrolet has fulfilled that fantasy, sort of. GM engineers have developed what they call "Flying Car Mode" for the Camaro Z/28, the most track-capable version of Chevy's muscle car. While it doesn't make the Camaro fly, it is a rather clever use of technology that's already on board when the Z/28 does get off the ground that allows the car to do faster laps.

Though getting air is not typically an issue on the road, on a race track with elevation changes you can get all four wheels to leave terra firma at the same time. While developing the new Z/28, the car was taken to the Nurburgring and they discovered that because of the way the vehicle's traction control system worked, whenever the car got air the system sensed wheel spin and cut power to the driving wheels, which meant that it slowed down when it hit the ground, producing slower lap times. Since bragging rights from the 'Ring have become a part of performance car marketing and since you can get air several times a lap there, a solution had to be found. The proposed solution GM engineers came up with was to deactivate traction control when the car is in the air. That will keep the wheels spinning under power, allowing the car to accelerate as soon as the wheels are back on the pavement. The question then becomes, how do the computers running things know that the car is off of the ground?

While the Z/28's Flying Car Mode was developed to around the 'Ring faster, this looks more like Milford, Michigan than Nürburg, Rhineland-Palatinate.

While the Z/28′s Flying Car Mode was developed to go around the 'Ring faster, this is the road course at the GM Proving Grounds near Milford, Michigan, not the Flugplatz near Nürburg, Rhineland-Palatinate.

GM's highest performance cars like the ZR1 Corvette, and the ZL-1 and Z/28 versions of the Camaro feature what the automaker calls the Performance Traction Management system, or PTM, which integrates traction control, Active Handling, and chassis mode selection to work together. Cars with PTM are equipped with ride height sensors. On the Z/28, when the PTM system senses full chassis drop from the ride height sensors, it goes into Flying Car Mode, deactivating traction control. GM says that keeping the wheels spinning when getting air saved them 5 seconds a lap at the 'Ring's Nordschleife circuit.

Bill Wise, Camaro Z/28 vehicle performance engineer, explained the details. "PTM uses torque, lateral acceleration and rear-axle wheel slip to define the amount of traction control required, but when the car clears a rise on the track, it normally wants to decrease torque to increase traction. The unique logic in the system uses the ride-height sensors to determine the reduction in force on the tires that's unique to track driving and allows the car to continue with uninterrupted momentum and, ultimately, a better lap time."

Once the ride height sensors detect that the wheels have touched down, the PTM system reactivates traction control.

PTM has five performance levels and the flying car logic is active, to varying degrees, in all five modes, so if you manage to catch some air while tooling around on public roads, you'll still hit the ground running, so to speak, but flying car mode is most effective in Mode 5, the setting Z/28 drivers would likely use on the track.

Source: General Motors.

Ronnie Schreiber edits Cars In Depth, a realistic perspective on cars & car culture and the original 3D car site. If you found this post worthwhile, you can get a parallax view at Cars In Depth. If the 3D thing freaks you out, don't worry, all the photo and video players in use at the site have mono options. Thanks for reading – RJS



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