Sprint Car Wings
Sprint Car Wings are one of the most distinguishing features of a Sprint Car. The huge 5ft x 5ft top wing mounted above the driver’s head is capable of generating huge amounts of downforce. While the wing may look reasonably agricultural compared to say a Champ Car or F1 wing, they make a huge difference to the handling and performance of a Sprint Car.
Sprint Cars also use small front wings or nose wings to help balance the car and to keep the front of the car planted to the track.
Wings weren’t always a part of Sprint Car Racing and didn’t appear until the 1970’s. The popularity of Sprint Car wings increased as teams realised the advantages to be had by running them. Introduced to create downforce, Sprint Car wings also provide large areas for sign writing and most importantly improved safety by acting as a crumple zone in the event of a roll over. In 1984 Ted Johnson announced that the World of Outlaws would only compete in winged Sprint Car events, up until this time World of Outlaws events were a mixture of winged and non-wing events. Winged Sprint Car Racing now dominates the sport around the world, with non-wing racing being more popular in the Mid-Western states of the USA.
How do they work?
Sprint Car wings act like upside down aircraft wings, creating downforce instead of lift. A wing generates downforce due to the air pressure differential between the top and bottom surfaces of the wing. Due to the shape and angle of attack of the wing the air below the wing travels faster than that above, meaning that its air pressure will be lower. The speed of the air above the wing is either not changed or slowed by the shape of the wing, meaning the pressure of the air above the wing is higher than the air flowing under the wing. The downforce is created as the high pressure area on top of the wing is drawn to the low pressure area under the wing forcing the wing down. As the speed of the wing moving through the air is increased, so is the downforce.
The wing angle is important for it to work efficiently. As the wing angle is increased so is the downforce, however this also increases the aerodynamic drag. Too much drag will reduce the car’s speed down long straights, this is not as much of a concern on smaller or slick race tracks. Too much wing angle can also cause what is known as wing stall, this is where the extreme angle of the wing can cause the air to separate on the wing surface, creating turbulence. This turbulence will reduce the amount of downforce and increase drag. A top wing angle of around 22-24 degrees is a good starting point when trying to find the optimum angle.
Tip Plates or Side Boards are used on Sprint Car wings to ensure that the high air pressure area moving over the top surface of the wing is not allowed to spill over the sides into the low pressure area under the wing and vice versa. If this is allowed to occur it produces a whirling vortex which affects the efficiency of the wing by reducing downforce, increasing drag and in some circumstances causing lift.
Another important job performed by the tip plates is to create what is known as sideforce. This is the force which acts towards the inside of the race track. To create sideforce the left tip plate is positioned higher above the wing than the right tip plate, this is to allow the high pressure air on top of the wing to push more on the left side of the wing. The right tip plate is positioned lower below the wing than the left tip plate, causing the low pressure area pull to increase on the right tip plate.
A Wickerbill or Gurney Flap is a small strip of metal added to the trailing edge of a wing. The theory behind a wickerbill is that it actually creates a small low pressure area behind the flap which speeds up the flow of air from under the wing, delaying separation and increasing downforce. Wickerbills of various sizes are used from around 1 inch to 3 inches. Caution should be used on high speed tracks as the use of a wickerbill will increase drag.
Some wing manufacturers are now adding rudders to the underside of their Sprint Car wings. The rudders help to keep the air moving under the wing cleanly and to stop flow separation.
Mounting the Wing
Sprint Car wings are mounted high above the drivers head to ensure that the flow of air under the wing is not disturbed by the car’s bodywork. The top wing is usually mounted centrally over the car (sideways). Care should be taken when mounting the wing to ensure that the brackets are as aerodynamically efficient as possible. Anything that disturbs the air under the wing will affect the performance of the wing. Most modern Sprint Car wings have internal slides which keep the brackets out of the air flow. The brackets that support the wing at the rear are known as wing trees and the front mounts are called wing posts.
Hydraulic Wing Adjusters
Hydraulic wing adjusters allow the driver to adjust the position of the top wing while racing. The driver adjusts the wing using a valve called a wing slider which is connected to a hydraulic ram. The ram allows forwards and backwards movement of the wing. The hydraulic wing adjuster uses hydraulic pressure from the power steering system of the car, this is why you will sometimes see a driver turning the steering wheel left to right when testing operation of the wing slider. Some sanctioning bodies have banned these devices to keep expenses down.
As mentioned earlier Front Wings or Nose Wings are used to keep the front of the car balanced. Without a front wing Sprint Cars would be very light in the front end and hard to control. A typical front wing is six square feet and most rules stipulate that it must be mounted behind the front nerf bar and not be wider than the width of the front tires.
There are a few important points to remember if you want your Sprint Car wings to perform as efficiently as possible. Ensure that surface of the wings are free from dents and holes, even things such as dome headed rivets can affect the air flow. Ensure any dirt is cleaned from the surface of the wings between races. As Sprint Car wings are subjected to extreme forces of up to 600 pounds it is imperative that all of the mounts and brackets are in good order. Many a great race has ended in tears after a wing has dropped or a tip plate has collapsed due to lack of support.
The wing can be used to alter a car’s handling characteristics. If a car is too tight or is understeering, the wing can be moved forward to increase the weight on the front of the car and decrease the weight on the rear. If a car is too loose or is oversteering the wing should be moved backwards to increase the weight on the rear.
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