At 01:56 PM 5/19/2015, meekerdb wrote:
Fast drivers used to delicately accelerate a rear wheel drive car into a turn to drift the rear end out slightly so the engine could contribute some centripetal force. Is this theory now deprecated?
It works in low traction situations, e.g. dirt road, snow,...
But on clean dry pavement it quickly overheats and wears out the tires, so it's not used deliberately in road racing.
You can see this technique best on the dirt-racing cars, where the rear wheels are kicking up an enormous amount of dirt and are constantly skidding while the front wheels track the line. The car is often at a substantial angle to the tangent -- e.g., perhaps 20-30 degrees -- so the front wheels have to be turned in the _opposite_ direction just to stay on course. Also, check out "donuts": https://en.wikipedia.org/wiki/Doughnut_%28driving%29 I'm not so sure that this is a "theory", so much as the only way you can possibly get around a course very fast. More-or-less, this is the way rear-wheel drive cars behave. If you're going down a street & want to reverse direction -- e.g., getting away from a potential kidnapper/terrorist -- you simply don't have enough street width to do a normal U-turn. So you floor it, turn the front wheel slightly, and then pull hard on the handbrake. The rear wheels lock up & break loose, the car does a 180 about the front wheels, you release the handbrake, straighten out the front wheels, and floor it out of there. (This is a lot more difficult on American cars where the "emergency" brake is a foot pedal, and also latches!!) The action movie guys love, love, love this maneuver.