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Thursday, August 12, 2010

Oops... Chrysler Techs Break Edison2 X-Prize Cars

In a blog post about the Progressive Automotive X-Prize, here, the sad tale of the coast-down testing at Chrysler's Chelsea Proving Grounds is told.  The Chrysler test drivers who were to run the coast-down tests accidentally over-revved both of the Edison2 cars, which use sequential manual transmissions, and blew up the engines.

Also on the morning of Day 3, Edison2, TW4XP, and X-Tracer hit the proving grounds for their turn through Coast Down. On the straight-away of the test track, Edison2's Mainstream Class entries, vehicle numbers 97 and 98, were fielded. In both cases, as third party test drivers accelerated the vehicles to speed, a mechanical over-rev condition resulted in engine failures and the tests had to be aborted.

The fact that the Edison2 vehicles employ sequential transmissions may have contributed to the unintended downshift and subsequent mechanical over-rev condition that damaged the engines. In a typical racing configuration, the driver pulls rearword on the shift lever to shift up through the gears. This is opposite the convention used by many US automakers in their semi-automatic transmissions (like Chrysler's AutoStick), where manual upshifting is executed by pushing forward, away from the driver. Further, given that this is a competition vehicle, the automated software that would normally override an unintended downshift at speed or at high RPM is not yet perfected.

All was not lost however.  Since the point of coast-down testing is to coast the vehicle to measure its decelerating forces, an engine isn't needed except to get up to speed.  Chrysler was able to save the day for Edison2 by pushing their cars up to speed with another vehicle.

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