What's My Line, Part II

What's My Line, Part II

     In part one; we looked at the “racing line” in the textbook design of a long straight followed by a 90 degree corner followed by another long straight. We looked at how the theoretical and geometric “lines” are similar. In part two, we’ll get into corner combinations and more.
     “Don’t use the brakes, they only slow you down!” While that statement is true, on a closed road course or on the street, it’s not realistic. The first phase of a corner is the actual braking zone. For beginners in road racing, new students are often encouraged to get all of their braking done in a straight line so that they can focus on the turn-in, apex and track-out points in a smooth and controlled manner. However, when you advance your driving technique, trail braking (or staying on the brakes as you turn in) gives the front end tires more “bite” or grip leading to better initial handling into the turn. Simultaneously, this forward weight transfer helps to lighten the rear of the car which then helps “rotate” the car into the corner thereby lessening steering input. So far so good. The balance of releasing the brake, coasting and re-applying the throttle while the wheels are still turned is all about good hand/eye coordination as well as the seat-of-the-pants feel.
     The theory of getting on the gas as soon as possible and going to full throttle as soon as possible is the same in any corner that leads onto a long straight. What you don’t want to do is get on the gas and then have to lift off and then re-apply. The time and momentum lost during that dance will be more than if you had just waited a bit longer to go full throttle or perhaps squeezed on the gas pedal a bit more smoothly (not an on/off switch) to sustain that acceleration.
     As we combine this with corner combinations, we need to look at which corners to “give up” in order to gain the maximum amount of speed for the rest of the lap. For example, if you have two 90 degree corners in succession (e.g. left then right) and the second corner is followed by a long straight, you’ll want to apex the first corner very late in order to take a better line through the second and be able to come off of that corner with maximum acceleration as soon as possible. The amount of time lost by not taking the textbook line through the first corner will be more than made up by the extra speed you’ll gain by coming off of the second corner better.
     How do you know which corners to prioritize for the best line? Start with the ones that lead onto the longest straights. Also, look at the highest speed corners as a tenth of a second gained at high speed is much more distance traveled than a tenth of a second at low speed.
In part three, we’ll look at more corner types and how rain affects the line.

 

By Larry Mason

Copyright © 2021 Larry Mason

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What's My Line?

Whats My Line

   One of the most fundamental aspects of safe and fast driving is making sure that you’re driving on the “proper line.” There are theoretical and geometrical lines to take through corners on the road and turns on the race track. Which is the best one for you? If you have two identical radius 90 degree corners, is the line the same through each one? Not necessarily. This is where the theory gets complicated just as quick as the geometry.

  The “line” is made up of a curve that includes multiple points of reference. In fact, before you even start turning in, there’s usually a braking point and zone before you get to the “turn in” point. After the turn in point you get to the apex, and from there you exit at the “track out” point. By connecting the dots in a smooth and wide radius, this allows the driver to lessen the steering input. This allows for more mid-corner speed which ultimately leads to a lower lap time.

  If you have an X long straightaway followed by another X long straightaway, with a 90 degree corner in the middle, the geometrical apex of the corner and the largest radius might be very close to the theoretical best line through the corner. However, it also depends upon what kind of car you’re driving and where you’re driving it. If it’s a high-horsepower car, you might want to move that apex point further away (later in the corner) from the geometric point.

  What are the results of hitting your apex early or late? If the corner is increasing radius, an early apex is okay. If it’s a “textbook” 90 degree or a decreasing radius corner, the results of an early apex can be severe. Once you’ve turned into an apex at speed, there’s very little correction that can be made if you’re not hitting it within a few inches. If you apex early, you will run out of room, or roadway position, at the exit. This typically brings up two responses – the first being that you lift off of the throttle because you’re carrying too much speed. The second being that you turn the steering wheel more to avoid driving off the outside edge of the road. Both of those actions combined can create a TTO, or Trailing Throttle Oversteer. The result is that at this point you can fly off the road surface backwards, or if you’re racing on a grand prix street course, you can hit the concrete barrier.

  If in contrast you apex late, you will leave excessive room on the roadway position at the track out point. It’s safer, and also slower. It’s also a great way to start to learn a track or an unfamiliar mountain road.

  In Part II, we’ll take a look at turn combinations and other aspects of driving the line.

By Larry Mason

Copyright © 2021 Larry Mason

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ABS – Always Be Steering!

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  Why use the brakes? They only slow you down! Of course I’m kidding when I say that. Using the brakes is an everyday occurrence whether you’re driving on the race track, the street, or even on your bicycle. Even though we know that pressing the brake pedal slows you down, there are nuances to be learned and understood in order to become a better driver.

Today we’ll look at how drivers can be safer, whether the cars have ABS or not. Technically speaking, ABS stands for Anti-lock Braking System. Here at Fast Lane we also like to say that it means Always Be Steering. You could also think about it as the Ability to Brake and Steer. That’s critical knowledge for driving everyday on the freeway or any other roads. ABS is a great technology that is designed to keep the front and rear wheels from “locking up” under heavy, quick or unloaded braking maneuvers. If you were to slam on the brakes, chances are that your brakes would lock up, meaning that your tires are no longer rotating; instead they are skidding on the road. Once your tire starts skidding, steering control is gone. It doesn’t matter which way you turn the steering wheel, the car will continue skidding in the same direction that it was going. Tires need to rotate to make the car change direction and that’s where ABS comes in. Keep in mind that ABS may not necessarily stop the car in a shorter distance (more on that next time); however, it gives you the ability to brake and steer. Here’s how: The vehicle has wheel speed sensors. Under heavy braking in a lock-up situation, the computer gets a signal telling it that the brakes are locked. At that point, the computer system automatically reduces brake pressure to allow that wheel to rotate. The computer also knows that you’re still mashing the brake pedal so it re-applies brake pressure. Typically at this point the lock-up returns. As soon as the system recognizes that the wheels aren’t turning, it reduces brake pressure again. This action can typically take place more than 20 times per second! That’s faster than a professional race car driver can do it. Furthermore, the system has the ability to modulate brake pressure with one wheel at a time - something that a professional driver could never do. Since 2008 all cars sold in America have been equipped with ABS. The systems have also become much more effective and have reduced the amount of noise and pedal push back (vibration) of earlier systems.

The beauty of ABS is that on slippery or uneven road conditions it can help the driver avoid danger. However the laws of physics still apply. Also, keep in mind that since the system is locking/un-locking, the time that it’s locked, you’re still sliding forward. On a dry high-grip surface this “sideways stair step” is minimized. Think lock – go straight, un-lock – turn. If you’re driving on wet or sandy roads, this sideways stair step turning pattern is amplified – meaning that when you turn the wheel under an ABS condition, the car will not go where it normally would in a dry non-ABS situation. You’ll have to turn the steering wheel more to help it trace the arc of turning you’d like. Always keep in mind what your car is capable of doing in varying road conditions. By the way, if your vehicle isn’t equipped with ABS, you’ll have to manually pump the brakes if they lock-up. It’s definitely a skill worth acquiring as otherwise you may find yourself on the wrong end of a crash. Bottom line is that when you come to Fast Lane Racing School, you’ll learn your car’s ABS limits in a safe and effective setting.

 

Copyright © 2021 Larry Mason

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Taking Your Braking to the Next Level

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  In the last blog post we focused on ABS. Today we’ll look at non-ABS brakes for track use. Techniques for braking on the track vary greatly depending upon the kind of race car you’re driving. Even though we’ve used the brakes all our lives, braking technique is critical for not only making passes in competition, but also lowering lap times and influencing how the car handles.

First, let’s look at brake pedal application. For cars with downforce (wings, diffusers, etc.) it’s critical to take advantage of all the extra grip high speeds provides. That means when it’s time to step on the brake pedal, don’t! Hammer that brake pedal like you want to destroy it! You can generate tremendous stopping power when you’re at high speed. However, as the speed rapidly bleeds off, you must also bleed off your brake pressure since you’re losing that downforce grip at slower speeds. Quick tip – Sledgehammer On, ease Off.

For cars without downforce, the technique is the opposite. You don’t want to dynamite the brakes as they will tend to lock-up. This is more of a squeeze the pedal on and rapidly ramp up the pressure until threshold braking is achieved. What’s threshold? The maximum braking force you can generate right before the moment of lock-up.

If you were to look at a graph of these two techniques, the former would show almost a digital zero-to-one on the upside and then ramping down from there. For the latter, it would be more like a parabolic curve ramping up.

Keep in mind that both of these techniques are for straight-line braking. Trail braking can still be used but you cannot apply maximum brake force. The laws of physics and vehicle dynamics still apply. The benefit of trail braking is that when you transfer weight forward, the reduced grip on the rear tires will help your car rotate into the corner.

One thing that you’ll do the same with both kinds of cars is to be mindful of “jumping off” the brakes. Work on the smoothness and timing of getting off the brakes so that you’re not inducing large amounts of understeer mid-corner. This, combined with a trail brake in and jump-off mid, can lead to the driver complaining about “it’s loose on corner entry and I have a big push coming off the corner.”

Lastly, use test days and practice sessions to push the limits not only on the racing line but off the line too so that you’re better prepared for potential passing spots during the race. Good luck and take your braking to the next level!

 

Copyright © 2021 Larry Mason

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