Coming up is the 102nd running of the Indy 500, so I thought I would do a simple analysis of the track; hopefully it will make watching the race more enjoyable. My guess is that Vehicle Dynamics Institute graduates and ISDA certified drivers will be familiar with the numbers.
The Indy track is 2.5 miles in length. The track consists of:
two long straights that are each 3,300 feet in length
two short straights that are 660 feet long
four corners are 1320 feet long
Looking at those numbers, an Indy driver will spend 40% of their time in a turn.
In 2017 the average speed of the winner (Takuma Sato) was about 226 MPH, but we will lower that number to a boring 220 MPH, which is 323.4 feet in a second, more than the length of a football field in a second. Blinking your eyes takes .2 seconds, the vehicle will travel 64.6 feet in a blink of an eye.
At 220 MPH it would take the vehicle 10.2 seconds to go the length of the long straight, and 2.04 seconds to travel the short straight, and 4.1 seconds in each corner.
Depending on the vehicle’s path and speed the cars will produce 3.5 G’s pushing on their Center of Gravity. That means that there is 3.5 times the weight of the vehicle pushing the vehicle away from the corner and towards the wall. Also four times a lap there is 3.5 times the weight of the driver pushing on the driver. If a driver weighs 175 pounds, there will be 612.5 pounds pushing on their neck four times a lap.
Under and Oversteer-Understanding the Basics
Throughout the race, you will hear the announcers mention the car is pushing, or it is loose. That is “announcer speak” for under or oversteer.
Under and Over Steer are used to explain vehicle characteristics.
Understeer (the Announcer guys call this “push”) is the condition where the front tires lose adhesion, while the rear tires remain in contact with the pavement. The car tends to travel straight ahead, even though the driver is turning the wheel.
Oversteer (Announcer guys call this “loose”) — is the condition where the rear tires lose adhesion, while the front tires remain in contact with the pavement. The back end of the car will slide out, actually snap out, is a better explanation.
You will also hear the announcers talk about the vehicle changing from under to oversteer, or vice versa, as the car is moving through the corner. As mentioned above the driver will be in the 1320-foot turn for about 4 seconds, and moving about 160 feet in a half of a second, with a car changing from understeer to understeer, and that can create some exciting driving.
Enjoy the race!
This post is authored by International Security Driver Association Member
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