The fundamental advantage of a mid-engine car is its ability to change direction quickly. Sir Isaac Newton's second law of motion, the F=ma that some of you learned in high school, relates the acceleration of a mass to the force that is needed. when you want to push a car forward by hand, there is a certain amount of resistance that must be overcome to get the car rolling. The car resists the motion and we say it has inertia.
That's fine for a car being pushed in a straight line, but what about a car changing direction? To do so it must rotate about an axis locates near its center of gravity. Think of pushing a children's merry-go-round, if all of the children are sitting on the outside edges of the disk, it is dificult to get the merry-go-round started. If all the children sit very close to the center, however, it is mush easier to start the rotation of the disk. The resistance to rotational motion is called the moment of inertia, and it depends on the overall mass and on how far the mass is located fron the center of rotation.
A Mid-Engine Car
Toyota MR 2
A mid-engine car has the majority of its mass-the emgine, the transmition, and the diver-located close to its center of gravity, very close to the rotational axis. When the driver whishes to change directon, the car rotates around this axis. With the mass centered nearby, the moment of inertia is low and the car changes direction quickly, with the application of minimal force. A front-engine, rear-wheel-drive car with the same mass and same location of its center of gravity, will have a higher moment of inertia, because its heavy parts are spread farther apart. The force required to get the front-engine car to begin turn will be higher. Likewise although it will be easier to start a mid-engine car spining, its moment of inertia is lower, so less efort will be needed to catch the spin and recovery will be quicker. With a front-engine car, the higher moment of inertia works agaist the driver. Making it harder to recover from a spin.
For a production car there are some disadvantages to a mid-engine layout. Frontal crash protection, engine cooling, and limited rearward visibility are traditonal problems. Also, placing the driver too far ahead of the rear axle makes it difficult to sense the beginings of a rear slide or spin.
Still, for a skilled driver on a twisty road, it's hard to beat the responses of a good mid-engine sports car.
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