Two Approaches To Maximizing The Mid-Corner Phase

Photo credit: Driver61

The mid-corner phase might be the most obscure part of the cornering process. The car isn’t accelerating, nor is it braking. Essentially, the tires are used almost entirely for turning here. This transitional period between brake and throttle is something of a gray area and depends largely on the circumstances, yet, it is one that drivers should try to understand thoroughly, since the all-important corner-exit phase depends on how assertively the car is turned.

There are a few basics to keep in mind when visualizing the process. Coming off the brake smoothly and applying the throttle neatly help keep a stable platform; refraining from a see-sawing motion helps maximize the load evenly across all four tires. This mid-corner period involves weight-shifting, both longitudinally and laterally, and because of the complexity of the situation, there are a couple schools of thought on how it should be done.

Driver61/Scott Mansell offers some practical tips on how to improve the basics of the mid-corner phase.

An even distribution of weight is the aim, regardless of the approach, but there are different interpretations with regard to steering, brakes, and vehicular rotation. The more conventional approach aims to minimize tire scrub through a smooth manipulation of the inputs, and in theory, it ought to be the fastest way around a corner. However, there are times when this textbook approach—borne out of a time when tires didn’t provide enough grip—isn’t ideal.

Due to bias-ply tires of yesteryear providing sub-par grip or response, a little bit of sliding would help a car point into the corner, and the mustachioed, cigarette-puffing, he-man at the wheel would carry slides much further in order to keep their momentum up before parking and rolling up to the bar for a highball. Current drivers avoid sliding their cars from the entry to the exit like they did forty years ago, and nowadays, the accepted techniques are the product of a few more factors.

The Role of Downforce

Matt Cresci keeps this Radical SR3 on the largest possible radius to maximize the downforce.

Drivers these days enjoy much more grip thanks to downforce, among other things. Modern racing cars are more and more stable under braking and acceleration. So now it’s more difficult to see the differences in driving technique during these phases, but the mid-section is an area where a little style is observable to the trained eye. Matt Cresci, 2016 Mazda Road to 24 Shootout Champion, notes, “With an aero car like a Radical SR3, you want the largest radius possible to maintain your aero advantage at a higher speed through the faster corners.” Keeping a steady flow of air over the wings provides the most available grip.

Thomas Merrill complements Cresci’s point by noting, “Something like a Pro Mazda has a lot of downforce, so at high-speed you aren’t necessarily inducing slides, so much as trying to carry speed as smoothly as possible without disturbing the aerodynamic platform.” Again, keeping the air flowing steadily over the wings means more grip, and that takes precedence over the shortest possible path through the corner.

Simraceway Instructor Greg Evans unravels the mystery even further: “By turning the car in gradually, you keep the radius higher for longer, allowing the car to use its downforce by keeping the speed high.”

Merrill avoids “disturbing the aerodynamic platform.” Photo credit: Thomas Merrill Motorsports.

However, there are a few more variables to consider. With appreciation of the tire, the type of corner, the car used, we turn to the advice of a man who’s tutored Kimi Raikkonen and Nigel Mansell, we learn that there’s more than one way to turn a car through the mid-corner section.

Bending the Car

Formula 1 guru Rob Wilson sheds some light on a somewhat unconventional technique that the best drivers understand, but is seldom explained in performance driving schools. While smoothness is typically regarded as the ideal way to go racing, especially at speed, there are small areas where more assertiveness with the steering and inputs can reap minimal but useful advantages.

This pertains to high-end machines with lots of grip and power, but holds some relevance to lesser formula cars and prototypes. It sometimes is helpful to try inducing a mild form of yaw, or zero-steer, mid-corner to minimize lateral loading and straighten the car sooner. This “bend” leads to what Wilson refers to as a “flat car,” which has the distribution over all four wheels about even. Acceleration is best in this state, since the straight-line performance isn’t hampered by lateral loading.

The Technique Involved

Basically, Wilson suggests Formula 1 drivers try and subtly shock the car into rotation during the mid-corner phase. This means not over-committing on the entry, and not following a constant radius throughout the corner. The way this plays out in real life might not stand out boldly to the casual observer.

While Wilson advocates the initial turn-in should be as smooth as possible, the steering rate should increase briefly as the driver rounds the apex or the middle of the corner. This way, the car pivots almost imperceptibly in the middle of the corner, where there’s the smallest penalty for tire scrub, and straightens out a hair earlier. It’s not a hairy drift, but a minute rotation that allows the driver to straighten the wheel without countersteering.

Wilson describes Jenson Button’s textbook-smooth style with the slightly more forceful style of Kimi Raikkonen.

The Benefits Involved with a V-Shaped Line

In comparison to the smooth style best practiced by Button, Raikkonen’s more assertive direction change is, apparently, easier on tires. This mid-corner yaw might be more abrupt, but it loads the tires for a shorter amount of time, and Wilson feels the degradation to the tires is minimized—especially if the car has a handling imbalance that will be exacerbated over the course of a longer corner.

By spending less time shifting the weight, the driver gets more time enjoying a flat car. While this style relies on a stable rear end, Wilson asserts it lengthens tire life, shortens the corner, and improves acceleration. In this comparison, Wilson notes how Vettel is able to edge ahead of teammate Raikkonen, whose lines are more U-shaped. It seems Raikkonen is more assertive than Button, but not as much as Vettel, who drives more of a V-shaped line than some of his smoother colleagues, and benefits from greater corner-exit acceleration as a result.

Now, Wilson coaches F1 drivers and his advice pertains to top-tier thoroughbreds with lots of grip and power. What about a slightly slower car with grip, but not quite the thrust?

Merrill in the Pro Mazda. Photo credit: Thomas Merrill Motorsports

Our contributing racers elucidate this approach in practice. “At low speed, if you can get the [Pro Mazda] rotated, it’s way more efficient,” Merrill adds, “But your slip-angle tolerance is extraordinarily narrow, so you’re not inducing it with any aggressive inputs; rather managing it with speed.” Cresci also employs this style of subtle-yet-forceful driving, adding “For slow corners (i.e. Turn 11 at Sonoma), I tend to hook it pretty hard mid-corner to get it pointed, so that I can get on the power harder on exit.” The straighter and “flatter” the car is, the earlier the car can accelerate full-throttle.

Wilson’s approach obviously focuses more on high-powered cars which have a lot of speed to gain under acceleration, and anemic machines like a Formula Ford might benefit from a little more entry speed at the expense of the exit. Not all techniques and lines are useful and/or possible with every car.

In a perfect world, Wilson’s arcane approach might yield the most performance, but perhaps it’s only for a select few. In any event, it’s acceptance at the top levels illustrates how there is more than one correct way to go about racing, and that each car, each set of tires, and each type of corner requires consideration and a specific treatment. The drivers with the most in their databank and the greatest ability to improvise appropriately given the parameters are those who stand above the rest.

We would like to give special thanks to our contributing racers. For more information on them, please check out their websites:  Matt Cresci RacingThomas Merrill MotorsportsGregory Evans.

 

About the author

Tommy Parry

Tommy Parry has been racing and writing about racing cars for the past seven years. As an automotive enthusiast from a young age, he worked jobs revolving around cars throughout high school, and tried his hand on the race track on his 20th birthday. After winning his first outdoor kart race, Tommy began working as an apprentice mechanic to amateur racers in the Bay Area to sharpen his mechanical understanding. He has worked as a track day instructor and automotive writer since 2012, and continues to race karts, formula cars, sedans, and rally cars in the San Francisco region.
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