This Sunday, May 28th is the 90th running of the Indianapolis 500 race. Join us this week on SciTech Watch as we explore the science and technology behind racing in the Indianapolis Racing League (IRL) at the 2.5-mile Indianapolis Motor Speedway oval track.
After 90 years of racing at Indianapolis, technology has taken car capabilities to a very high level. These cars are capable of running in excess of 225 miles per hour for extended periods of time. Their aerodynamics have evolved to use the forces acting on the car to improve stability and speed of the car on the track. Advanced technology is found throughout the IRL. Technology helps increase the cars performance, monitor the engineering state of the cars, protect the drivers, and control the race for maximum safety.
The cars that race in the IRL are open-wheel cars, meaning there is no bodywork or fenders around the wheels. The engine is located in the middle of the car behind the driver. The engine drives the rear wheels through a six-speed transmission. The tires used on open wheel racers are 11 to 15 inches wide and smooth, with no tread. At any given time on the track the total surface-area of tire in contact with the track is about one square foot. At race speed the tires have an almost tar-like consistency to exert maximum grip.
The chassis of the IRL cars are manufactured by either Dallara or Panoz. They are constructed of carbon fiber and composites and typically weigh about 1500 lbs, excluding fuel and the driver. Each car has a 30-gallon rupture-proof fuel tank and is 192 inches long and 78 inches wide. The Dallara chassis is pictured above.
The car is aerodynamically controlled by two major wing surfaces: there are wings on either side of the nose cone and a large wing at the rear of the car behind the rear wheels. Increasing the angle of the wings on the nose of the car forces the front tires down harder on to the track improving steering response. There are three separate rear wing designs. Different designs are used depending on the type of track the cars are racing on. At Indianapolis they use a single plane wing with no flaps. On bigger tracks, a two-element wing is used to increase down force and drag helping to keep the cars at safe speeds. On short tracks or road courses a three-element wing is used to provide maximum down force.
The engines for the cars are manufactured by Honda using an aluminum cylinder block. The upper part of the engine is gold plated to help radiate heat. An electronic engine management system, supplied by Motorola, controls a capacitive discharge ignition system. The engine is structurally part of the frame lending its mass to strengthen the chassis. This year the fuel used by the IRL racers will be a blend of methanol and ethanol. Historically, IRL cars ran on pure methanol. In 2007 the cars will switch to pure ethanol as fuel, sending the message that ethanol fuel can be high performance as well as eco-friendly.
As in any high-performance sport, there is always the possibility of injury to drivers or fans if something unexpected happens on the track. Spectators at the track are protected by a large debris-retaining fence. The fence stands between all public areas, the track, and pit proper. It is constructed of heavy-gauge wire mesh with reinforcing half-inch steel cables. The fences are 15 to 20 feet tall with an additional three to six feet of overhang, which curves back over the track. The overhang is designed to catch flying debris and allow it to fall back on to the track.
The IRL race cars and tracks contain many innovative safety features. When a caution is declared during a race, in addition to the yellow flag waving and yellow flashing lights situated around the track, a yellow light also blinks in the cockpit of each race car letting the driver unequivocally know a caution is in progress. Tethers are attached to key suspension and chassis points to prevent the exposed wheel and suspension assemblies from becoming completely detached during a crash. The steering column of the cars is designed to collapse in a collision, keeping the column from hurting the driver. All the tracks where the IRL races now have a significant portion of their race track walls upgraded with an energy-absorbing materialknown as the SAFER (Steel and Foam Energy Reduction) Barrier. When a car collides with this wall, the Styrofoam inserts behind the steel outer wall absorb energy from the contact resulting in less force being transmitted to the driver and reducing the chance of severe injury.
All cars carry Delphi’s Accident Data Recorder. Serving much like an airplane’s flight data recorder, the Accident Data Recorder captures data about the force and direction of the crash for later analysis. If the recorder detects conditions that exceed preset levels, a special indicator is lit signaling to the safety crew that driver injuries are more likely.
There are over 100 people dedicated to the safety of the drivers and race fans. Thirty-eight doctors and nurses are on site to treat both fans and drivers. A four-truck, 17-member safety team is on stand-by during practice and races to respond to incidents on the track during races and practice sessions. Each safety truck carries equipment such as hydraulic cutters, fire extinguishers, and video cameras at the front and rear. All crewmembers are certified paramedics or firefighters. They arrive at the scene of an on-track incident within 30 seconds.
To accurately determine the car’s position on the track for accurate restarts and finishes, each car carries a radio transmitter positioned 33 inches from the tip of the nose code. Cabling buried under the track collects the signals from the cars and provides timing and scoring information. This allows each team to know where their car and others are in relation to one another. The timing information is accurate to one ten-thousandth of a second. A camera located at the start-finish line snaps pictures at the same interval. The camera played a vital role in determining the race winner at Kansas in 2004 when Buddy Rice edged Vitor Meira by .005 of a second. The timing data is distributed to the racing teams and the public via a sophisticated client-server application written specifically for the IRL.