E0061 High-Performance Driving V 2 - theory principle P 2; spin, sliding, momentum - EulSeoggy Ko - 笑える動画、感動する動画、話題の動画をご紹介します。

Why is sliding and spinning necessary in high-performance driving? When a large cornering force acts, the vehicle's center of gravity is high, and the tire frictional force is large, then, the vehicle may roll over. However, if the rear wheel slides or spins when the cornering force is large, the tire frictional force decreases, and oversteer occurs, allowing the vehicle to pass through a road with a sharp corner without rollover. The force caused by the excessive braking system torque exceeds the maximum frictional force on the road surface, so the vehicle does not stop and slides on the road surface with the rotation of the wheels stopped due to the force of vehicle inertia, which is called sliding. The power caused by excessive engine torque exceeds the maximum tire frictional force, so the engine power is not transmitted to the road surface and the driving wheels are idling. This phenomenon is called spin. In order to start high-performance driving, it is essential to secure the necessary vehicle momentum. Linear momentum or translational momentum is defined as the product of the mass and velocity of an object. It is a vector quantity having both a magnitude and a direction. Linear momentum is the momentum when an object moves at a constant speed along a straight line without rotation, and angular momentum is the momentum when an object rotates. Just like the law of conservation of energy, momentum is also subject to the law of conservation. If the wheel torque of the brake system is less than the wheel torque due to the maximum road friction, no sliding occurs. If the wheel torque supplied by the engine is equal to or less than the wheel torque due to maximum tire friction, wheel spin will not occur. When the handbrake is applied at full stroke, the weight of the vehicle moves forward, increasing the normal load on the front wheels and decreasing the normal load on the rear wheels, so the friction circles on the front wheels increase, allowing all vehicle controls such as steering and braking. On the other hand, since the rear wheel friction circle is relatively small and easily reaches the maximum braking force, it is easily pushed outward even with a small lateral force. Therefore, the rear wheels are easily locked, and sharp cornering and 180-degree J-turns can be achieved by operating the steering wheel and intentionally generating a yaw motion. In rear-wheel drive, if you use spin on the rear wheels, oversteer can occur even without using the brakes, so you don't need to use the handbrake. when a rear-wheel drive vehicle accelerates rapidly at a low gear that can produce large torque during right-hand turning, spin occurs in the rear wheels, and the angular speed of the rear wheels is much higher than that of the front wheels. When spin occurs, the friction coefficient is lowered, so the rear wheel cannot handle the centripetal force and is pushed outward, resulting in oversteer of the vehicle and yawing motion. In the case of front-wheel drive vehicles, oversteer using spin is not possible. In the case of cornering with oversteer, let's compare rear-wheel drive and front-wheel drive. In rear-wheel drive, when large engine torque is applied to the rear wheels without using the handbrake, rear-wheel spin occurs. This rear-wheel spin can cause oversteer, allowing you to corner fast, so you can corner without significantly reducing vehicle speed. In front-wheel drive, rear-wheel sliding occurs with the handbrake, and the resulting oversteer help you corner, so the vehicle speed is reduced compared to rear-wheel drive during cornering. In this way, rear-wheel drive uses accelerated spin to corner faster than front-wheel drive, so high-performance drivers prefer rear-wheel drive. Another advantage of rear-wheel drive is greater maximum acceleration compared to front-wheel drive at the same engine torque. Any object that rotates will continue to rotate unless an external force is at play. This is called rotational inertia, denoted by J, and also called moment of inertia, or angular mass. When the rotational torque is the same, a vehicle with a longer wheelbase generally has a larger rotational inertia compared to a vehicle with shorter one, so it takes a longer time for change of angular velocity. Therefore, oversteer occurs slowly when the wheelbase is long, and oversteer occurs quickly when the wheelbase is short. Therefore, when driving at high performance with a vehicle with a long wheelbase, the vehicle's behavior progresses slowly, allowing you to feel the movement of the vehicle while driving.
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投稿日時：2023年09月9日　16時37分
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