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Scandinavian flick
The Scandinavian flick, Finnish flick, Manji Drifting, or Pendulum turn, is a technique used in rallying. While approaching the turn the driver applies a slight steering input to the opposite direction of the turn, then steering into the turn, while sharply lifting off the throttle and (in some cases, depending on speed and type of layout) lightly applying the brakes. This will cause the car to slide sideways facing slightly away from the turn. Then steering input is applied towards the turn and as the driver releases the brake pedal while still holding down the throttle the car will slingshot itself around the corner to the desired direction. Of course, countersteering will again be required to control the induced oversteer.
This technique is used to help the driver get around corners that had an increasing radius, but it is also used as a show off as the result of the flick involves the car oversteering heavily.
This technique is explained and demonstrated in an 1990 Top Gear segment in a Mitsubishi Galant VR-4 rally car. <ref> Galant rally driving on Google video</ref>
Origin of the name
Though it's not clear who was the first one to invent it, it is named after the Scandinavian rally racers of the '60s who widely used it. This was in response to SAAB's change in handbrake operation when the Saab 99 model replaced the Saab 96 (the handbrake changed from operating on the rear wheels to operating on the front wheels). The "flick" part comes from the technique of "flicking" the wheel in a direction opposite of the turn to build up inertial energy. Nowadays it becomes even more popular with Norwegian and Swedish racers as an attempt to debunk the myth that FWD cars are prone to understeer.
Physics involved
Every time you turn, the centrifugal force attempts to cause your vehicle to continue moving straight. The force is directed towards the outer side of the turn (e.g. right when you turn left). This is partially neutralized by the friction between the tires and the road, so the vehicle rather tilts than slides. As you abruptly flick the steering wheel in the opposite direction, the inertia of the vehicle that has hitherto been trying to slide in the opposite way is added to the force applied by the engine and the friction of the front wheels, thus exceeding the force necessary to break traction between the tires and the tarmac. Since most cars have their engines in the front, the load on the rear tires is less, so they break traction first, effectively causing the rear to slide out. Lifting off the throttle, especially in FWD cars, causes additional weight transfer to the front, making the load on the rear wheels even less.
If the traction between the tires and the tarmac is too great, the effect would be the vehicle rolling over instead of sliding. Rally cars and cars designed for the specific purpose of drifting have hardened suspensions to ensure this would not happen. The harder the shocks, the more force is needed to tilt the body enough to roll over, hence there's greater chance that the wheels would break traction before the body passes the critical point of lateral stability.
Real life usage
Most cars today are FWD and prone to understeer. This can be very dangerous at high speeds. To make things worse, in-turn braking with a FWD vehicle is likely to start an uncontrollable skidding or spinning. Skilled drivers are able to correct understeer by using a maneuver similar to the Scandinavian flick, though with less steering input and control the possible slide by using an opposite lock. In the best of cases, the driver would use the inertia of the feint to make the car enter the bend without initiating a slide. This requires excellent knowledge of the specific car.
However, less skilled drivers must not attempt to use this technique, as it can prove more dangerous than the understeer itself.
The ability of a vehicle to handle sudden changes in direction at high speeds without sliding or rolling over is assessed through the so-called Moose test. This scenario occurs when the driver is trying to avoid an obstacle (allegedly a moose, or any other large animal that may appear on the road) in his or her lane and then returning back to the lane to avoid oncoming traffic. The succession of sharp turns in opposite directions combined with lifting off the throttle is exactly how the Scandinavian flick is performed. Since the technique is used at race speeds, it's not normal for a vehicle to start a slide while driving at cruise speeds.
It is possible to induce oversteer at 30 mph (45 km/h), which is well in the cruise speed range. However, it is not likely that in real life the driver would change the steering input from hard left to hard right within 2 seconds.
Usage in Drifting
In terms of drifting, the Scandinavian flick is classified as a weight transfer drift. It is also known as a Feint drift or Inertial drift. It's widely used in rally racing, because it is simple to perform and does not require engine power, nor does it cause a loss of speed at the exit of the corner. A drawback of the technique is that it requires somewhat wider tracks than the other drifting techniques.
Dangers
There are two basic dangers when performing the Scandinavian flick
- If the center of gravity is too high (as in a SUV), there's a great chance the vehicle would roll over instead of sliding.
- It takes practice to learn how to control the vehicle during the slide. A less experienced driver would be prone to overcompensating for the slide and driving off the bend.
Also, a drift is not likely to occur if the camber of the rear wheels is set too negative. On the other hand, if the camber of the front wheels is set too positive, they will break traction in the same moment the rear ones do, so the car will slide uncontrollably rather than pivoting around the front wheels.
References
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External links
Keiichi Tsuchyia's Drift Bible Part 2 (Weight transfer drifts, including feint drift)
