Racing NASCAR vehicles is a complex task that involves endurance and strength as well as an amazing understanding of how air moves around a racers car. Both for race performance and safety measures, parts are added to cars and modified to allow vehicles to move through the air stream more effectively.
The process of manipulating the air stream to win a race is known as drafting.
Often referred to as seeing the air, experienced drivers can aid race teams by implementing techniques like bump drafting, normal drafting, and previously tandem drafting, all in an effort to win a tight race. As the cars whip around the race track, disturbances in the air stream occur, and as is obvious by the view from the race control tower, talented drivers utilize drafting to come in first; here is how they do it.
How Does NASCAR Drafting Work?
Drafting is an aerodynamic term for the practice of increasing downforce and reducing drag resistance during a racing series. The pressure friction and drag friction present on race cars sap energy the engine requires more HP to reach the same top speeds.
By moving into different positions behind or in front of other cars, racers can implement drafting, which does anything from increasing tire traction on turns to generating a higher top speed than restrictor plates typically allow. This is common on tracks like Daytona International Speedway.
A draft-savvy driver can find the perfect balance of increased downforces to take tight turns better and a reduced drag on straightaways, often resulting in race teams riding bumper to bumper, creating a draft line. In all racing series, draft lines occur with the front bumpers of trailing cars inches from the rear bumpers of lead cars, creating an exciting situation with faster car speeds and an increased chance of crashes.
The energy of crashes is directed downward, preventing cars and car parts from flying into the spectator areas, which happened in 2013 and resulted in the banning of tandem drafting.
What Does It Mean When a Driver Drafts?
In stock-car racing terminology, drafting is when the racing teams take advantage of disruptions in the air stream to drive faster, use less fuel, or take the lead in unexpected ways. Drafting on large tracks involves creating speed on straightaways and increasing downforce and traction to offset centrifugal forces on turn-heavy tracks like Bristol Motor Speedway.
To improve the fast-moving cars’ effects on the airflow, a metal blade is added under the front bumper to cut the wind, and a solid sheet metal base prevents air from getting under the car, creating lift.
A driver will use drafting to bring a car’s speed from 180 miles per hour to over 200 MPH. On a majority of tracks drafting will be a term used by announcers with frequent references to when a driver is a side-drafting car, lead-lap car, or trails to take advantage of less pressure friction and reduced tire fatigue.
Race directors will also pay attention to the type of drafting used and whether or not officials need to be notified of dangerous instances of downforce and drag ratios.
When Should a Driver Draft?
A driver should draft anytime downforce can be increased, and pressure friction in the form of drag can be reduced. This aerodynamic technique is utilized throughout the race whether by forming a draft line for the long stretches of laps or to get advantage positions at the end of each stage or the final checkered lap.
On road courses, the weight distribution of cars making both left and right turns leads to common drafting situations and collaborations with a drafting partner. Cooperative drafting is a common race technique on larger tracks to help reduce the times a car needs to go down pit road or for a partner to wave around cars through turbulent air currents creating race-winning conditions.
What is the Science Behind Drafting?
The top speeds a car can go, as well as the fuel per mile and other car metrics, are limited by the size of the engine cylinder, the amount of HP, and the effects of airflow on a vehicle. Since the first two factors are highly regulated by the NASCAR commission, the main advantage a driver can find to push their car a few kilometers per hour faster has to do with how they reduce drag and increase downforce.
Even a movement of half a percent can move a car 10 pacers closer to first, so the drafting technique is heavily researched and practiced by race teams and drivers.
Currently, the car of tomorrow uses a metal piece in front and in the back to reduce the drag of airflow. As the rear downforce increase, the front tires will lift, but a car behind will prevent this from happening, increasing drag reduction and increasing engine power for both racers.
Decreasing the air pressure around cars does strange things, and good draft positions can allow racers to make strategic moves and win races. Perfecting the use of the pressure differential is something all racers work on in the days of practice leading up to a race since reduced air resistance is directly correlated to a difference in position on the track.
Types of Drafting Used in NASCAR
There are several types of drafting that are incorporated into NASCAR that allow drivers to achieve seemingly impossible racing feats. Higher top speeds on courses with restrictor plates and control over aerodynamic forces are just a few of the advantages a driver that understands the drafting process can gain.
Drafting speeds and the suspense of a possible class with cars inches from each other can turn a dull race into a nail-biting affair and leave fans on the edge of their seats for the entire race. Below are some common drafting techniques and how they work.
|Two-Car Drafting||One car follows directly behind the lead car||The drag is reduced on both cars, and a speed increase is possible|
|Bump Drafting||A car uses the draft to catch up to and bump the lead car when their car has the least traction on the track||The lead car may be pushed to an outside lane and lose the drafting advantage, and the inner lane track benefit|
|Multi-Car Drafting||A car joins the front or end of the draft line||This increases the top speed of every car in the collective draft line|
|Lead Drafting||The lead driver allows the trailing driver to get too close for too long||The trailing race cars engine is unable to get the cool air needed to bring the temperatures down, leading to the oversized engines overheating|
|Tandem Drafting||Tandem drafting is when the trailing driver hooks their bumper to the lead car’s rear bumper creating one supercar||Although greater speeds are possible, the trailing driver may not be able to disconnect from the lead car, which could result in them losing control, so race officials have banned tandem drafting as too dangerous|
How Critical is Drafting for NASCAR Drivers?
Since so many features of NASCAR race cars are regulated to prevent richer teams from having a huge advantage over less wealthy teams, drafting is one of the few techniques drivers can employ to win races. Drafting’s role in racing cannot be overstated, as without it, races would be boring and far less eventful.
Moves like the slingshot and other showy drifting moves are a huge draw for fans and create a more challenging racing environment for drivers.
Increased Top Speeds
On tracks that use restrictor plates, drafting allows for faster speedways and breaks up huge lumps of cars. As more cars join the draft line, the top speed of all the cars increases until the chain is broken, and cars move to solidify a lead position at the end of a race stage.
Better Control on Turns
Drafting can help a rear car huge turns tighter and can also be used to cause a lead car to lose control. By playing with downforce, a drafting driver can use turns to make moves and move up several positions during a race.
On road courses with left and right turns to draft and an increased downforce becomes even more important.
Reduced Fuel Usage
As drafting cars follow the lead car, they are using less fuel punching through the wall of air that is always present. The lead car uses all of its HP to punch through the increasing air pressure, and the rear car gets skipped over as the airflow separates and then slams back together further back. Saving fuel for the final push can allow a drafting car to pass a leader and win the race.
Fewer Pit Stops
Without the constant barrage of air and with more traction being applied, a chain of drafting cars stops fewer times for pits stops, but once a stop is made, a car must leave the draft line, which can have negative consequences. It is hard to gain and reconnect to a draft chain that has left a racer behind.
A More Entertaining Race
Drafting requires cars to be close and gives drivers an additional arsenal of tricks to use throughout the race. When cars are this close, the chance of bumps, swerves and crashes increases. Fans always love a good show and seeing this more often is one of the reasons drafting is allowed, even if it is a bit more dangerous.
Techniques like the slingshot make spectators happy and encourage drivers to learn how to perfect drafting and make it work in NASCAR races.