Control system instability

Remember the Dukes of Hazard? No, I mean the General Lee, not Daisy Duke! The General Lee was a 1969 Dodge Charger with a Hemi Orange paint scheme. I bought a brand new 1970 Charger R/T 440 in the same color (no, that’s not a photo of my Charger). Of course I got rid of it long before the Dukes of Hazard aired on TV. For me, the car was notable for the looks (sporty), the throaty rumble of the exhaust, the gas milage (very poor), and the kick in the rear acceleration. Wheel spin on demand was available, and sometimes even when you didn’t want it. And the 426 hemi model had a lot more oomph than mine.

Sadly, last week a 1970 Dodge Charger was in the local news. Michael Corvino, president of JanSport (you may own a JanSport backpack), lost control, crashed his Charger into a tree, and was killed. The highway patrol’s reconstruction based on witnesses and skid marks indicates he started making a left turn at an intersection and induced wheel spin, causing the rear end to break loose and slide to the right. He corrected by steering right, but over corrected, so the car’s rear end slid to the left and the car left the road and struck a tree right at the driver’s door.

Normally, the vehicle’s control system (the driver) can react fast enough (has minimal delay) to compensate for such a rear end skid. But control systems become unstable when there is too much delay between the input (observing the car’s skid) and the output (making a change in the throttle and steering). In this case the excess delay was caused by Mr. Corvino’s blood alcohol level of .21, nearly 3 times the legal limit. This crash was a very unfortunate illustration of driving with a defective control system due to alcohol impairment.