By Elizabeth Swan
Small Times Special Correspondent
When 32 gentlemen and one lady start their engines back home in Indiana Sunday, specialized MEMS accelerometers will be along for the ride.
The tiny devices will feed a steady stream of performance information to pit crews as the 33 open-wheeled cars reach speeds of more than 225 miles per hour during the 85th running of the Indianapolis 500 race.
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| Tiny devices will feed a stream of performance information to pit crews as the 33 open-wheeled cars reach speeds of more than 225 miles per hour |
The Indy Racing League (IRL) allows race teams to install a variety of sensors on cars, including the commonly used three-axis accelerometer. The competing Championship Auto Racing Teams (CART) league has more restrictive sensor regulations, but also allows the three-axis accelerometers on cars during testing and racing.
This sensor, available in both a MEMS and conventional version, measures three areas of interest for engineers:
* Inline acceleration, defined as accelerating and braking.
* Lateral acceleration, the reason your coffee cup flies out the car window when you turn.
* Vertical acceleration, which measures gravitational forces.
Strictly speaking, the force measured on all three axes could be referred to as G-forces, or G-loading in racing terms. Most teams are mainly interested in the lateral measurements that will tell how well the car’s tires are gripping the racing surface.
Pi Research of Indianapolis provides the majority of the micro-machined devices for the CART series.
Information transmitted by small tech sensors gives race teams the needed statistics to make a car go faster under varying conditions. The information they provide helps pit crews set up the car’s handling characteristics for qualifying runs and race day, sometimes making the difference between starting on the pole or starting in the hole.
But the vertical measurement can also be important when it comes to driver safety. During the recent CART event at Texas Motor Speedway the combination of vertical and lateral acceleration reached forces that some considered beyond the threshold of human tolerance.
During the race, recorded lateral acceleration averaged over 4 Gs, or more than four times a driver’s normal body weight, in the highly banked corners. Forces peaked at nearly 6 Gs on the corners. At the same time, vertical acceleration averaged about 2.5 Gs.
The G-forces drivers were experiencing were higher and longer than those sustained by space shuttle astronauts during liftoff. Many drivers complained of dizziness and disorientation following practice sessions due to the force put on their bodies while traveling at speeds upward of 230 mph.
Safety is also a key focus point for the sanctioning bodies and teams alike.
For the past four seasons, Ford Racing Advanced Technology has partnered with CART as the Official Technologies provider. One of the primary focuses of the relationship is the so-called “blue box.”
Often compared to the “black box” flight recorder of an aircraft, the blue box is a small sensor pack that is mounted in the cockpit of the car and records the force and direction of impact should an accident occur. Information collected during a crash helps teams and medical professionals to better understand driver tolerances.
The unit draws power from the car’s own electrical system, which allows the sensor to remain in place for constant monitoring of all practice, qualifying and race sessions.
The information collected during testing also helps Ford and other auto companies develop safer passenger vehicles, said Dan Davis, director of Ford Racing technology. Ford, Oldsmobile, Mercedes-Benz, Toyota, and Honda all either currently have or have had relationships with race teams in past years.
Small tech also help racing teams improve performance despite CART rules restricting both sensor use on cars as well as the times teams are allowed to test cars on the track.
Reynard Racing Cars, a chassis supplier in the CART series, uses a specialized piece of equipment called a seven-post shaker rig in Indianapolis which many teams utilize to improve track performance. The rig is essentially a large table which uses computer programs to replicate race track conditions.
A race car is placed on the table and the rig creates a computer profile of how the car could be expected to perform with the handling adjustments
This equipment allows teams to better set up cars for the actual events. For example, accelerometers placed on the wheel uprights during testing allow teams to measure how well the tires follow the track. This gives teams and drivers the opportunity to go back over data and perhaps find areas where lap times can be improved.
Henri Kowalczyk, director of the Seven-Post Program for Reynard says that the information gathered by small technology tools is invaluable.
“On the seven-post rig we can, for example, measure the acceleration that is input by each wheel ram and measure it at the wheel uprights,” said Kowalczyk. “Using the track data from the wheel uprights and the three-axis accelerometer data we can use the computer to generate the correct input that would simulate what the car would see on the track.
“In other words, we create a ‘track map’ that we can then input different scenarios and conditions to test on the computer rather than going out to the circuit and actually running the car.”
With the high cost of open wheel racing (between $10 million to $15 million per season for one car) the ability to test without hitting the track is a welcome one for many teams.