Aero and Gearing Setup for the iRacing FR2.0 Part 2

Aero for the iRacing FR2.0 Part 2

Wings, Rake and Drive Train--Practical

Intro:

OK, now with some basic background information gained from testing, let’s get practical and work on just how to choose the ideal aero settings. First, we have to choose a reasonable starting point, and then we need to understand the cause and effect of adjustments.

To start, let’s hear what two really fast guys had to say recently in the iRacing Forum:

“The vast majority of tracks in this car will be 'full downforce', meaning 31 front and 12/13 rear. This car is very low drag even with the wing on it so unless a track has very very long straights you can usually turn the wing right up and gain speed.

Ultimately you just have to test and see what is faster, but glancing at the schedule, Laguna Seca will be full downforce, so will Donington.  Silverstone, Canadian Tire and Road America may slightly reduced.”

---Thomas Jordan (iRating=6311)

and

 “I did some testing in Watkins Glen today and managed a 41.9. Replay is attached and hope it helps someone to analyse. I was driving a high downforce-setup with 31/15 wings.”

----Fredy Eugster (iRating=8011)

Take a look at the following diagram. We will use it to generally compare the advantages and disadvantages of high and low downforce. The car approaches point “A” at high speed, under full throttle. The driver “lifts” and begins braking.

In the Braking Zone from “A” to “B”, the car with high downforce will have an advantage. Brakes can be applied later and harder since the tires have more grip. The ideal relative front vs rear wing settings are affected by brake bias, spring and damper settings.

As the car approaches the Corner Entry Zone, brakes are modulated (reduced) and steering input is added. Again, high downforce generally provide an advantage here.  Higher downforce produces the biggest advantage in the Mid Corner Zone, although the relative front vs rear wing setting is also very important, Too much relative rear wing will cause understeer; too little will cause oversteer. In addition, the ideal front vs rear wing settings are affected by other set-up parameters, such as spring, damper, ARB and camber settings as well as rake--and especially the differential settings.

Another important factor in Mid Corner is driver input in the Mid Corner Zone as well as driver input in the prior Braking and Corner Entry zones. (Faster entry and trail braking will produce more rotation.)

As the car approaches the Apex, and the Corner Exit Zone, full throttle is introduced as steering input is reduced. Again, higher downforce generally produces an advantage.

So, from points “A” to “D” and to the Track Out, higher downforce produces an advantage. But, at that point the higher drag that accompanies higher downforce will reduce acceleration, resulting in an average lower speed from points E to F and a lower terminal Top Speed.

So, essentiailly we are balancing the benefits in A-D against the penalties from high downforce in E-F. We are also adjusting the relative front vs rear settings to achieve the optimum overall speed through the corner.

Developing a keen sense of whether the car is understeering or oversteering in various sections is critical for making adjustments—of wing settings and rake, as well as many other set-up settings. 

So, always be aware of what the car is doing in sections A-B, B-C, and C-D. A-B is Corner Entry, B-C is Mid Corner and C-D is Corner Exit. There are many definitions of understeer and oversteer. The engineering definition has to do with “slip angle”. Slip angle being the difference between the actual line of tire travel as compared to the line of travel that would occur with the tire rotating without any slip.

Here is my simple definition from a driver’s point of view—Understeer is where the car is rotating and changing direction more slowly than you would like. Oversteer is where the car is rotating and changing direction faster than you would like.  So, by my definition, understeer and oversteer, like beauty “is in the eye of the beholder”.  A veteran pro driver once told me: “When the car is understeering, you see the wall as you hit it going forwards, but when the car is oversteering you hit the wall going backwards.”  

When we get to the final fine tuning, we will use tire temperatures to help bridge the gap between the driver’s point of view and the engineering definition, but at the start, focus on the driver’s perception.

 OK, again. “How do I choose a starting point?” 

There are two schools of thought on this. One is to start with low downforce—optimize the handling with the ideal chassis adjustments and then add downforce for additional cornering speed. I prefer instead to start with high downforce and a “baseline” chassis setup. The driver goes out and pushes the car hard, “driving it like he stole it”.  With the extra downforce, the car will theoretically have reserve grip and recovery from mistakes is easier.

BTW—When I refer to “baseline” chassic setup, I AM NOT referring to the Baseline provided by iRacing.  I will address “How to build three baseline setups” in a later article. For now, use the setup you liked the best for Mazda Laguna Seca for a starting point. If you have no clue—use the iRacing “low downforce” setup, and change to 800# springs all around, reduce fuel to 2 gal, and set Rear ARB to P1 Stiff as a starting point.

High Downforce Setting

We will have a discussion regarding the FR2.0’s special three spring, monoshock front in another article,  One should realize that roll stiffness on this design is achieved very differently than with the conventional four spring suspension found on the Pro Mazda for example. And, the rear ARB will produce much different effects. One can achieve increased roll stiffness by increasing rear spring rates, but again, the resulting effect will be different than on other cars. We will go into this in more detail later. 

So, follow the advice of the experts, Jordan and Eugster.  Start with 31 front and 15 rear. Leave the front wing alone and test reducing the rear wing from 15 down to 12. Choose the rear setting that gives you the most comfort (understeer vs oversteer in the fast corners) and best lap times. Then, test the other setup variables changing from your original baseline settings.  When you feel you have a “balanced” race car, with the right balance of understeer and oversteer that suits you, as well as tire temperature “balance” front to rear on the same side, keep driving to improve your lap times until you consistently get close to your optimal lap time consistently over 3 or 4 laps. Note your top speed at the end of the longest, fastest straight.  (Compare this to other laps you can see on iSpeed, iAnalyze, VRS, or YouTube videos. I always view Thomas Jordan, GTROS (Spanish) and Apex Academy, as well as other drivers’ YouTube videos and always gain some insight/s.)

More or Less “Balanced” regarding Tire Temps (Note camber will make inside warmer)

A reminder: Higher downforce produces the biggest advantage in the Mid Corner Zone, although the relative front vs rear wing setting is also very important, Too much relative rear wing will cause understeer; too little will cause oversteer. In addition, the ideal front vs rear wing settings are affected by other set-up parameters, such as spring, damper and camber settings as well as rake.  So, if the car is understeering or ”pushing” in mid-corner, reduce rear wing a click and try again. If the car is oversteering or “loose” in mid-corner, consider adding rear wing, or reducing front wing a click. (One remedy to a car that rotates too quickly (oversteers) at the beginning of the mid corner is to use “maintenance throttle” but generally there are other more effective ways of dealing with that on the FR2.0.)

Keep in mind the car will not be the same in every corner, so the final “best” is the setting that produces the best overall lap time. Concentrate most on the corners where you using 4th or 5th gear in Mid Corner--downforce is big at 100 mph+. 

Now, test running with lower downforce. Reduce front and rear wings, maintaining the general relative balance between the settings. You will see your top speed increase. You will probably also note significant changes of understeer and oversteer in various corners which may require minor setup adjustments. Continue to reduce downforce as long as your lap times improve.

Note: If you hit the rev limiter in 7^th gear only briefly, you may wish to leave it in low 7^th , especially for lone qualifying or time trials. In a race, where drafting might be very important, consider going to the high 7^th.

Medium High Downforce Setting

One big word of caution. Often, drivers make adjustments to the setup as they are practicing and see lap times improve. They mistakenly assume the setup adjustment was the cause, when in fact, it was simply their driving that improved.  Always go back and reverse the change to see if the perceived advantage from the setup change disappears.

Another word of caution. Often drivers will see their lap times improve when they reduce downforce because they did not utilize all of the tire grip when using the higher downforce settings.  Higher wing settings will provide higher grip and more cornering speed—and to a point—the faster you go through the corner, the faster you CAN GO through the corner. So be sure you are driving the car to the limit all the time during your setup testing. Most inexperienced drivers do not achieve the ideal slip angle for the rear tires, so keep in mind that the car will go faster if you sense a slight oversteering tendency in the Mid-Corner and Corner Exit.

Medium Low Downforce Setting

Ultra Low Downforce Setting

Other than LeMans, the Medium Low Downforce Setting is probably as low as most drivers will ever need, so I assume that the practical range is:

Front Wing:     24---31

Rear Wing:       5---15

Warning. iRacing tinkers with the physics from time to time, so you should assume that some of the “perfect” settings will need to be revised from time to time after updates. (Many can remember that issue in the Pro Mazda.) The process presented here for determining the perfect setting for you should continue to apply.

With experience, you will develop “intuition” and will be able to home in on the correct settings quite quickly.  You can also cheat a bit by discovering what other fast guys are using. But, as I have said—no two humans are the same and often the best setup for you is NOT the same as another guy is using, especially when the other guy has earned an iRating a few thousand points higher than yours.  And, to a degree, wing settings are dependent on other setup settings.

Finally, remember that all humans make mistakes, and in a race, you will encounter many unexpected circumstances. Be sure you have a final setup for your race and time trial that has some “reserve” handling that allows you to maintain control.

Aero and Gearing Setup for the iRacing FR2.0 Part 1

Aero for the iRacing FR2.0

Wings, Rake and Drive Train--The Data

Intro:

Being able to go through corners at a high rate of speed is an important characteristic of a race car. This is in addition to the car’s ability to accelerate and attain a high terminal, top speed.

The cornering speed is dependent on grip produced by all four tires. Grip is highly dependent on the downward force of the tire against the pavement.  Adding weight provides more grip, but comes with the cost of higher inertia in the corners.  Since the additional grip from added downward force is not “linear” meaning that it has diminishing returns, adding weight actually reduces cornering speed.

But, with aerodynamic downforce, there is no additional weight, just downward force produced by air flow over the body and wings. Hence, significant grip is added and significant higher cornering speeds is achieved. An added benefit is that the added grip actually increases exponentially with speed.  With aero downforce, more speed produces more grip which allows more speed

.

Aero downforce is a relatively new technology. Before the 1970’s, cornering g-forces above 1.5 were impossible. Today, some really fast cars are generating cornering g-forces at the 4.0 level. Here is a link for more background about race car aero:

http://wsspeedanalytics.blogspot.com/2017/03/downforce-and-aero-in-racecar-pt-1.html

Now, let’s focus on the iRacing FR2.0. There are essentially five (5) different adjustments that will affect changes to aero downforce and drag: 1) Front Wing Setting (14-31); 2) Rear Wing Setting (4-18), 3) Front Ride Height, 4) Left Rear Ride Height; and 5) Right Rear Ride Height.

More wing produces more downforce which provides more grip, but comes at the cost of more aerodynamic drag which reduces acceleration and top speed.  The process of optimization is much more complex than the concept. Often the best result is achieved only through a series of experiments or trial and error. And, such experiments take less time if you know the generally expected cause and effect from your changes, and if you have a reasonable starting point.

In addition to wings, downforce is affected by ride height.  Ride height affects two types of downforces, ground effects at the underside of the car and downforce from the incline or rake that it produces by air pushing on the top of the car’s bodywork.  Both of these types are affected by the rake or the amount the rear is higher than the front.  Ground effects become more important as the front ot the car is lowered, reducing the amount of air that flows under the car from the front.

Testing:

Knowing the “best” settings and more importantly the effects of various settings requires testing and experimentation. So, let’s go to our “test track” that I use for testing aero effects in iRacing. I take the FR2.0 to Talladega, the longest (2.66 mile/4.28 km) oval track available. We use telemetry to measure speed and ride height at the fastest flat section.

Here are the initial settings “A”:

Front Spring (700#)  Ride Height (0.658”)

Rear Springs (800#)  Ride Height L/R (1.046)

Static Rake  1.046-0.658 = 0.388”

Rear End  Standard 9/30

7^th Gear  High

Front Wing: 31 Max

Rear Wing:  18 Max

We will refer to this as Max Wing, Min Rake

A Results (Max Wing/Min Rake):

Top Speed of 152.1 mph (7300 RPM)

Dynamic Rake at Top Speed  0.540-0.440 = 0.100”

Front Pushed Down at Top Speed  0.218” (33%)

Rear Pushed Down at Top Speed 0.506”  (48%)

We then changed the wing settings to minimum while keeping all else the same. This we refer to as the “B” settings with Minimum Wing and Minimum Rake:

Front Spring (700#)  Ride Height (0.658”)

Rear Springs (800#)  Ride Height L/R (1.046)

Static Rake  1.046-0.658 = 0.388”

Rear End  Standard 9/30

7^th Gear  High

Front Wing: 14 Min

Rear Wing:  4 Min

B Results (Min Wing/Min Rake):

Top Speed of 157 mph  (7500 RPM—Hit Rev Limiter)

Top Speed of 159 mph  (7250 RPM—Rear End 10/30 with Low 7^th Gear)

Dynamic Rake at Top Speed  0.660-0.560 = 0.100”

Front Pushed Down at Top Speed  0.098”  (15%)

Rear Pushed Down at Top Speed 0.386”  (.37%)

We then changed the rear ride heights to increase Static Rake, while keeping all else the same. This we refer to as “C” settings with Minimum Wing and Maximum Rake:

Front Spring (700#)  Ride Height (0.660”)

Rear Springs (800#)  Ride Height L/R (1.343)

Static Rake  1.343-0.660 = 0.683”

Rear End  10/30

7^th Gear  Low

Front Wing: 14 Min

Rear Wing:  4 Min

C Results (Min Wing/Max Rake):

Top Speed of 158 mph

Dynamic Rake at Top Speed  0.880-0.530 = 0.350”

Front Pushed Down at Top Speed  0.130”  (20%)

Rear Pushed Down at Top Speed 0.463”  (34%)

So the A, B and C settings provide insight as to the effects of wing and rake settings over the entire range, from minimum to maximum.  While it is theoretically possible that a rear wing setting higher than 15 might be beneficial, personal experience indicates that a settings of 31 Front and 15 Rear with the maximum rake would be considered HIGH DOWNFORCE.

So let’s test that as “HDF” settings:

Front Spring (700#)  Ride Height (0.660”)

Rear Springs (800#)  Ride Height L/R (1.343)

Static Rake  1.343-0.660 = 0.683”

Rear End  Standard 9/30

7^th Gear  High

Front Wing: 31 Max

Rear Wing: 15 (3 clicks below Max)

HDF Results (Max HDF Wing/Max Rake):

Top Speed of 152.1 mph

Dynamic Rake at Top Speed  0.820-0.400 = 0.420”

Front Pushed Down at Top Speed  0.260”  (39%)

Rear Pushed Down at Top Speed 0.523”  (39%)

Note 1: The HDF setting with Low 7^th and 9/30 Rear hit maximum speed of 149-150 at Rev Limiter RPM of 7500.  Essentially the 9/30 Rear is used almost at every track, and the High 7th is used when top speed above 149 mph is desired and achievable. 

 

Note 2: Changing the Front Spring in the HDF settings to 800# resulted in a 0.2 mph faster speed of 152.3 mph, with Dynamic Rake of 0.820-0.460= 0.360”

Next we test changes in cornering force:

I took the FR2.0 to the Centripedal Test Track--ran it on the band/lane, 4th in from the outermost band/lane. Morning Default. Normal race settings, with 25/4 wing settings. (This is minimum rear with front set for a "balanced setup" using tire wear/temp.) Max steady speed of 125mph. Increased to 31/11 wing. Max steady speed increased 3 mph to 128. (Tire pressure does matter as I was 0.5 mph faster with 1 psi increase.)

Increasing downforce can result in higher cornering speeds of 3 mph, with a corresponding decrease in top speed of 3 to 5 mph IF speed above 150 mph with low downforce is achievable.

This is a lot of data to digest, so I will provide an additional article with more discussion in regards to how to apply this knowledge in Part 2. 

Basic Set Up Training for the iRacing FR2.0

Basic Set Up Training for the iRacing FR2.0

Intro

For the benefit of the iRacing FR2.0 “community” I will be sharing a series of articles.

This series of articles is not intended to impart every bit of race car wisdom ever discovered.   They are intended to provide a foundation of knowledge that will allow you to “build” a setup that will allow you to race at a reasonably competitive level as compared to others with similar physical abilities and racing experience.

I am a Mechanical Engineer who has studied vehicle dynamics for nearly 50 years.  Over the years, I have developed a reasonable level of competence as a racing driver.  However, I am far from being even close to the abilities of top rated drivers.  Whatever limited success I have achieved in racing has been due almost entirely on “building a faster car” through engineering and development.  So, think of me not as a driver coach, but rather as an experienced Crew Chief or Race Engineer. My goal is not to impress you, but rather to simply be a helpful resource to some. I really love the "sport" of iRacing. I hope this basic info makes the "sport" more fun for those that find it helpful. 

For the FR2.0, there are services that publish setups that have been tested by some really talented drivers. They provide great value to many, especially if coupled with one on one driver coaching.  I highly recommend the one on one coaching offered by VRS and Wyatt Gooden.(A great deal of my knowledge regarding the iRacing FR2.0 came as the result of Wyatt Gooden coaching.) I also highly recommend using the Youtube hot lap videos provided by Thomas Jordan. The Driver61 website by Scott Mansell is also an excellent resource.  But, no matter what resources you use, I submit that you will be a better driver, and will derive much more satisfaction from your racing activities if you understand the basics of how to setup the race car yourself.

Keep in mind, there is no “magic” setup that will allow every driver to become a champion, or even to reach their best potential.  Performance on the track is the result of the “combination” of driver and machine.  Since no two humans are exactly alike, the best setup for each will vary.  In fact, the best setup may vary significantly from one driver to another.

Driving a race car is all about managing forces—directly created by the driver, and those that result indirectly. Think “action” and “re-action”.  Optimizing these forces to achieve the fastest lap is the ultimate goal.

Before we get into specifics---I will introduce a very important basic concept: 

The Balanced Race Car

Every driver input, thru throttle, braking and/or steering introduces a force.  These forces (Engine Torque, Braking Torque, Tire Slip Angle each in combination with Tire Grip) directly produce acceleration, with either a change in speed or direction, or a change in both. Rolling Resistance, Inertia, and Aerodynamic Drag are “resistive” forces that are affected by the race car setup or design.  Resistive forces resist the change of speed and/or direction.  All of these forces are affected to some degree by environmental conditions, such as weather and track condition.

The Balanced Race Car is one that achieves the optimization of all these forces to produce the fastest lap. This “balance” is achieved by the optimum combination of driver input/s and car set up, given a certain car design and a certain set of track conditions.

The concept of optimization is simple to understand when there are only two variables—the concept of trade-off---benefits have costs.  For example: More wing produces more downforce which provides more grip, but comes at the cost of more aerodynamic drag which reduces acceleration and top speed.  The process of optimization is much more complex than the concept. Often the best result is achieved only through a series of experiments or trial and error. And, such experiments take less time if you know the generally expected cause and effect from your changes, and if you have a reasonable starting point.

Here is a simple graph of lap time vs wing angle.  Increasing wing produces more downforce and more grip allowing faster laps until the cost in aero drag begins to outweigh the benefits—you lose more time in the straights than you gain in the corners. There is an optimum setting. Notice that I did not trouble myself with the curve of downforce vs wing angle. That relationship is complicated by the fact that it is affected by speed.  (We will devote an entire article to wing and other aero settings.)

An important assumption of this optimization of wing is that the driver pushes the car to the limit of grip in the braking zone and throughout each corner.  Often, drivers will not do so in their testing and will not gain the maximum benefit from higher downforce.

Most variables are best optimized by direct testing of how changes affect lap times. The “balanced” race car is the one that is the fastest with a given driver under the given track conditions.

Many variables/settings can be optimized more quickly by using the driver’s feedback regarding how the car “feels” in corner entry, mid-corner, and corner exit.  Here the three simple concepts of understeer or push, vs oversteer or loose, vs neutral are important.  Adjustments can be made to the car and driver inputs to optimize the car’s handling—again the optimum being the combination that produces the best lap time.  In the case of most drivers, a car that understeers slightly on corner entry and oversteers slightly in mid corner and corner exit is both faster and more stable—especially in racing conditions with traffic.

Another caution. Often, the cause of a driver’s feedback comment is poor technique. For example, entering a corner too slowly and accelerating too early can often make a driver complain that the car is too understeery. Using VRS, iSpeed, or iAnalyze telemetry to compare the driver’s technique to others is useful in evaluating this.  

One “gauge” of being balanced is tire temperature.  Tire temperature is a proxy or “gauge” of cornering force. When the temps for the front and rear tires on the same side of the car are significantly different, it is often an indication that cornering force is not being optimized.  (This depends on the car to some degree—but for each car with a balanced setup there is an optimal relationship between tire temps for the front and rear tires on the same side of the car.)  If the front tires are relatively too hot, then the car has too much understeer and is wasting available grip and cornering force from the rear tires. If the rear tires are relatively too hot, the car has too much oversteer and is wasting available grip and corning force from the front tires.  There is one exception to this rule—in setting up a car for fast 2 lap qualifying or racing on a very cold track, it may be optimal to run a setup that tends more toward oversteer-if the driver is comfortable.  

If the tire temps are not in balance as mentioned above, the handling becomes progressively unstable on a hot track after a few laps as once the tires exceed a certain temp, they lose grip rapidly and begin sliding more, generating even more heat and temp. 

It may surprise some, but in real life, there is a lot less adjusting of the setup at the track than most people realize. Generally, almost every ideal setup for a given track can be derived by making relatively minor changes to one of three basic setups for a given driver.  So, the goal is often to produce those three basic (driver specific) setups and then use them as a starting point when making the final adjustments to achieve the balanced setup for a specific track and track conditions.

Future articles will cover more detailed info regarding:

Wings, Rake and Aero

Dampers and Springs

Differential Settings

Camber/Caster/Toe

Tire Pressure and Brake Bias

Asymmetrical Setups

Brake Force Diagram

Probably one of the least understood aspects of road racing is the need to modulate the brake force when approaching a corner. The above figure denotes the force vs time/distance of a "typical" brake application at the end of a straight, approaching a slow corner. 

The racing car typically has aero downforce proportional with speed. And, even with cars having low downforce, more force can be applied initially before weight is transferred.

Threshold braking is the maximum braking force that can be applied without locking up the tires.

As the car slows, downforce is reduced and weight is transferred to the front. Braking force must be gradually reduced. 

In most instances, a lower brake force can be maintained as steering is added--reducing the brake force as steering is added and more cornering force is applied to the tires. This is called Trail Braking.

Depending on the brake bias settings, trail braking can cause the car to rotate (oversteer), but too much may cause the front tires to be overloaded, causing understeer.  Trail braking is used differently on different cars and in different corners, in different ways to control the car on corner entry. (On some really heavy cars, you never trail brake as it overloads the front tires. On these cars you brake in a straight line and "roll thru" the corner much like driving on a short track oval.) 

An often forgotten phenomenon is the fact that the car typically will tend to rotate when the brakes are released during trail braking.  (It has to do with the fact that upon brake release, the front tires no longer have a braking force competing with the turning force and the front will turn more sharply momentarily.)

The very best drivers will use this phenomenon to apply throttle just as, or slightly before the brakes are released as initial throttle often causes understeer, and the "brake release rotation" oversteer can offset this. 

Downforce and "Aero" in a Racecar - Pt 1

A critical part of setting up most modern racing cars is optimizing or "balancing" the additional grip in the corners provided by aerodynamic downforce with the associated drag that reduces acceleration and top speed.

Aerodynamics is an extremely complicated subject, even for engineers, so it is not a surprise that many "rules of thumb" are adopted by some, and then defended with almost religious intensity against anyone who challenges the over-simplifications.

The goal of racing is to finish ahead of your competitors.  This is accomplished by any combination of "factors":  a) A faster car; b) A more skilled driver; c) A driver with very fast reflexes; and d) A car/driver able to maintain control in the event of unexpected or unpredictable on-track challenges.

First, for those not interested in over-simplifications, here are links to excellent "primers" for every racing driver/engineer:

Stockholm Seminar Slides

Katz Book @ Amazon: Race-Car-Aerodynamics

Also, I suggest just to "Google" the term "Katz Race Car Aerodynamics" for some papers he has written.

In iRacing, you will quickly find there are spirited debates on the "best" setup.  Each car has it's own forum and "community" and each community seems to have one (or more) self appointed and usually well intentioned "guru" who promotes a certain "rules of thumb". For the most part, I find most of these rules of thumbs to be over-simplifications and often based on faulty engineering and racing principles.


For the most part, this discussion will be about cars running in the iRacing sim, but most of the principles apply as well to real life.  There are some exceptions. iRacing is a racing simulation--a very sophisticated video game.  Being successful in iRacing is somewhat related to being successful in video games. In real life--mistakes are very costly in terms of money and personal injury. In iRacing mistakes are pretty much remedied with a simple reset button. 


A brief history:

As you can see, the widespread use of downforce began in the 1970's. Above is a "wingless" Lotus with essentially no downforce.  (Those who promote the concept of "low downforce is always better" should be drive the Lotus 49--it is a real handfull and much slower than a comparable modern car with downforce.)

The first use of downforce was to use inverted wings--take an airplane wing and turn it upside down. From the photo below, it can be seen that even that did not keep the car on the pavement.

The development over the years has advanced to include spoilers to reduce lift, drag reducing bodywork and "undercar" effects as seen above.

In essence, these graphs shows the benefit from downforce:

Grip, or the amount of lateral force that can be transmitted to the car in the corner increases dramatically with the vertical force on the tire/s AND the slip angle--to a point. So anything that decreases lift or increases downforce increases grip in the corner.

In addition, anything that decreases lift or increases downforce also increases braking and acceleration forces that can be input through the tire.

So..more downforce gives shorting braking distances and faster deceleration, along with increases in lateral cornering forces and less wheel spin on acceleration. Faster corner approach, faster corner speed, and faster corner exit.

Of course, these enormous benefits come with a cost:  DRAG.  For the most part, increases in downforce produce increased drag--sort of like having a parachute attached.

The balancing act is this:

If there is a shortage of grip in the corners (too much sliding or a loss of control) then downforce will increase grip and increase speed POTENTIAL in mid corner. (The driver must utilize some of all of this potential speed.)

If the track requires hard braking, then downforce will allow the car to approach the corner with more speed and will allow it to accelerate out of the corner faster.

But...Increased drag will REDUCE the rate of acceleration and top speed.

For example, lets examine just part of the race track---the long straight along with the corner leading to the straight and the one immediately following the straight:

A) The car with high downforce will enter the straight with more speed.
B) The car with high downforce will accelerate more slowly and will achieve a lower top speed.
C)  The car with high downforce will be able to brake later and harder at the end of the straight.
D) The car with high downforce will travel through the ending corner with more speed.

You will often hear, "With high downforce, you are a sitting duck--you will be passed on the straights".  Well, that depends on how much more downforce you are running than your competitor.
The higher downforce car will be slower for a part, BUT NOT ALL, of the straight. Typically, the lower downforce car will gain significantly in the second half of the straight, up until the braking zone.

But, here is a comeback.

If the downforce produces sufficient benefits, the car with higher downforce may have built a sufficient gap that the speed advantage of the lower downforce car is insufficient to close the gap. (So often, it depends on whether there is a sufficiently long series of turns before the long straight to build a gap--think Atlanta vs Road America or Spa.)

In many cases, the passing process will include the braking zone, and here the high downforce car has the advantage. It is not a certainty that the lower downforce car can complete the pass.

And, a car with higher downforce, can mitigate the speed loss from drag, by using the draft of the car ahead, and then may be able to outbrake the car ahead and complete a pass in the braking zone.

When the last corner of the race is a high speed one, where downforce produces an advantage--like at Indy, I have seen the 2nd place car with higher downforce pop out of the draft, passing for the lead going into T3 and using the superior grip thru T4 to win the race.

But...a "logical" argument for low downforce, even for inexperienced drivers is that it is easier to go fast on the straights than it is to use the maximum corner grip that provides the major speed advantage from higher downforce. This argument assumes that inexperienced driver will brake earlier, drive slower in mid-corner, and get on throttle later than the more experienced drivers.

What I have noticed is that once the less experienced driver witnesses other cars pulling away in the corners, he/she will often push the car harder-invariably too hard---and will lose control.

Let''s review:

The goal of racing is to finish ahead of your competitors.  This is accomplished by any combination of "factors":  a) A faster car; b) A more skilled driver; c) A driver with very fast reflexes; and d) A car/driver able to maintain control in the event of unexpected or unpredictable on-track challenges.

a) There is always an "optimum" downforce that will produce the theoretical "fastest" car.
b) A skilled driver will be able to fully optimize the car's speed potential--however it is setup.
c) A driver with very fast reflexes will be able to drive a car with lower downforce.
d) Often, situations occur that require higher levels of grip than normal and anticipated.

The claim that a driver with very fast reflexes will be able to drive a car with lower downforce has to do with the fact that the road surface is uneven and the corner radius is not constant. Grip requirements change thru the braking zone and through the corner--requiring lots of changing driver inputs. A higher downforce will produce some "reserve" grip---not needed by the driver with lightning fast reflexes, but quite beneficial for the driver with slower reaction times. This holds true also in those unanticipated track events that invariably occur in racing traffic.

In conclusion:  1) Downforce settings are driver dependent--each driver may require or desire a different level; 2) Having a certain level of "reserve" grip  from a higher downforce can be beneficial; 3) The lowest downforce nor even the theoretical "fastest" car will NOT win races with more frequency than a car with a reasonable level of "reserve" grip in the hands of a skilled driver who can "fully optimize the car's speed potential"--however it is setup.

A marginal excess of downforce, if not excessive, is not like "training wheels" for beginners. In fact, a marginal excess of downforce, while admittedly helping some less experienced drivers, will often provide the greatest benefit to the most experienced driver who has the knowledge and skill to optimize the car's speed potential.

My personal opinion is that the best or "optimal" setup is not the one that produces the fastest hot lap, but rather the setup that provides the fastest average speed over about ten laps, with the least variation or standard deviation from the average.

Note:  Keep in mind that increasing downforce only helps if there is a shortage of grip. Here is a test:

Take iRacing's HPD Prototype, set it for LOW downforce and run it flat out at Indy. You never lift nor slide. (There is no shortage of grip.) Using MEDIUM downforce will result in lap times 4% slower.  Then do the same test at The Milwaukee Mile track.  Even though the MEDIUM downforce car will be slower on the straights, the lap times will be around 3% faster than the LOW downforce setup.

Even a modern race car with lots of downforce will fly 😎:

The Diving Turn

"It is amazing how may drivers, even at the Formula One Level, think that the brakes are for slowing the car down." - Mario Andretti

This is a famous quote that brings attention to the critical aspect of "dynamic weight transfer" in the process of making the race car handle.

The art and science of getting a race car to go through turns at maximum speed is greatly related to using throttle and brakes to move weight from the rear to the front tires and vice versa.

Reducing throttle or "lifting" causes weight to transfer from the rear tires to the front. The same weight transfer occurs when applying brakes. Adjusting shock damping rates will affect the speed at which the weight transfer occurs.

Similarly, releasing the brakes will allow weight to move back to the rear. Applying throttle will move weight from the front to the rear.

All this weight transferring is for the purpose of helping the car to turn (rotate) with the least amount of lost speed. 

There is no place where this process is more critical than where a track has a "diving turn". One example of a high speed "diving turn" is T2 at Mosport. Another is T1 at Interlagos. Another, but less obvious one is the T4-T5 Esses at Road Atlanta.  A slower speed "diving turn" is the Corkscrew at Laguna Seca. 

A diving turn presents a special challenge. As the front tires crests and begins to "fall" down the hill, the weight on the front tires and hence the grip is substantially reduced. This is followed rapidly by the rear tires cresting the hill where grip is reduced further. Often the driver will introduce steering to compensate for understeer on the lighter front and is surprised by a sudden oversteer just after the rear tires crest the hill. 

On a car with wings, one can increase grip by creating more downforce, but still the effect of the diving is to reduce grip from its maximum "pre-dive" level.

So, the "trick" is to use throttle and/or brake to cause downward momentum of the front, forcing the tires to better follow the terrain, just at the moment the front tires crest the hill. This is quickly followed by throttle application to counteract the loss of weight on the rear as those tires crest the hill and the car begins it's turn. This is more complicated if the turn is part of a braking zone, like Interlagos and Laguna where it is a matter of modulating brake input to adjust the weight transfer from rear to front, and then followed by modulation of throttle. 

Get the timing of this process right, and the speed through the corner is remarkably increased. 

So, as alluded to by Mario, brakes and throttle are tools not just for slowing down and speeding up--they are tools to be used to make the car turn--just as important as the steering wheel.

For those like me that really are fascinated by the complexity of vehicle dynamics--here is a link to an interesting presentation...pay attention to the "polar moment of inertia" concept:

Load Transfer Dynamics