Deceleration from high speeds

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Deceleration from high speeds

Deceleration from high speeds
Ready for break off

In contrast to airplanes, even bikes with a speed of 300 km / h do not take off. An effective delay is therefore all the more important.

Waldemar Schwarz

08/13/2002

Sunday morning at seven: The empty autobahn from Singen to Stuttgart encourages brisk pace, and that’s why the speedometer needle stops Kawasaki ZX-12 R beyond the last line on the scale. That marks the sound barrier: 300 km / h. Only a lonely omnibus pulls its path almost 300 meters ahead. So no need to flicker your right hand. But all of a sudden the tourist container pulls to the left in order to overtake a Dutch trailer team that was previously hidden from the motorcyclist. Now just concentrate on the brakes and their dosage, it shoots through the driver’s head. In just under eight seconds, the rear of the bus zooms in from the small point to the original size in the motorcyclist’s optics, finally stabilizing in front of the Kawa after a braking distance of 450 meters at 100 km / h.
The braking distance appears almost infinite. Not by chance, because with increasing speed, the stopping distances increase quadratically. From 300 km / h the braking distance is nine times longer with the same deceleration, from 200 km / h four times longer than from 100 km / h. A small consolation: The air, which brakes the driver disproportionately with increasing speed, provides help. At 300 km / h the air resistance decelerates the motorcycle with the throttle grip closed and the clutch pulled at 6.2 m / s², a value that the normal rider only achieves as a maximum at low speeds. But the wind brake quickly subsides. At 200 km / h it is only 2.9 m / s², at 100 km / h including rolling resistance it is just 1.2 m / s². The air resistance thus supports the braking by adding to its own deceleration.
During the test, test driver Carsten Schwers manages a deceleration of almost 15 m / s² when braking from 250 km / h, while from 100 km / h there is only 10 m / s². Moto GP rider Sete Gibernau couldn’t do much better. With the factory Suzuki he brakes the start-finish straight in Katalunya from 300 km / h with a remarkable 20.8 m / s², at 250 km / h it is just above the level of the ZX-12 R..
Values ​​that good sports cars achieve. Only Formula 1 racers can make huge gains in the delay. Also on the Catalunya racetrack, Nick Heidfeld manages a sensational 41 m / s² in a Sauber Petronas when braking on the start-finish straight at 300 km / h, a value that exceeds four times the force of gravity. It is not only the extreme aerodynamic drag of the monoposto that helps thanks to the catastrophic aerodynamics, but even more the enormous downforce, with which the racing car is pressed onto the asphalt by aerodynamic aids at 300 km / h with around three times its own weight and can therefore achieve high decelerations.
But one thing applies equally to two- and four-wheel pilots: Despite the airy support, it is advisable to always leave a sufficient air cushion between you and the person in front at high speeds.

Braking from 300 km / h

Formula 1 brakes everything on two and four wheels at high speeds and is vastly superior to even top-class sports cars. A Moto GP bike is far less dominant than super sports two-wheelers (left). The lower speed reduction of the Kawasaki ZX 12-R compared to the Grand Prix bike between 220 and 150 km / h (below) results from the higher slip on the front wheel, which increases sharply at irregular intervals. The air resistance alone makes a major contribution to deceleration at high speeds (left) and supports the driver when braking. At low speeds, only the rolling resistance is then effective.

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