Indy Cars

High Speed Race Car Collision with a Solid Wall

This article was written by P. Van Valkenburgh for Racecar Engineering Magazine.

The data has been slightly revised to maintain the confidentially of the driver and the team, but the results are typical of a high-speed Indy car crash into a solid barrier. The driver sustained no injuries. The analysis is based on a video film of the general vehicle path and crash dynamics of the on-board IST data recorder.

The data shown is a resultant of the combination of longitudinal, lateral and vertical accelerations of the car produced by its interaction w ith the wall. The acceleration is plotted in g versus time (in milliseconds). The sequence of events was as follows:

Event A

The rear of the gearbox strikes the wall, producing a longitudinal acceleration of short duration (10 ms) with a 56g peak. The right rear wheel strikes the wall and the suspension crushes, transmitting the impact to the chassis, producing the 10-20G acceleration until.

Event B

The suspension (tire) bottoms out against the chassis and produces a peak acceleration of 39g, which is followed by a rebound of the car from the wall and a clockwise rotation of the car. The sequence from A to B takes 0.05 seconds.

Event C

While the car rotates, a longitudinal acceleration of about 10g is indicated by the spinning of the car about its center of mass. This acceleration, which appears as a steady state value for about 0.125 second, is probably not longitudinal, but centrifugal acceleration due to the location of the transducer not being at the center of the rotation. If we can infer that the car rotated about 90 degrees in that time, then the angular rate would be 0.5 seconds per revolution. Using the equation: g = 1.22 x radius/time squared, the radius of rotation would be about 2 feet.

Event D

The care strikes its right front wheel against the wall resulting in a peak lateral acceleration of 55g and a duration of 0.015 second. The car continues to rotate until.

Event E

The nose and side structure impact the wall producing a peak lateral acceleration of 37G with a duration of 0.030 seconds. The front of the car then rebounds off the wall and.

Event F

The car continues the spinning motion down the track.

Indy race cars are equipped with CRASH DATA RECORDERS to improve safety

Not many of us make our living driving an automobile 220+ miles per hour, for hours at a time, in a high-speed, high -stakes, high-risk racing competition. But for those of us who do, the issues of safety, protection, and survivability in the event of a crash or mishap are important ones.

This year for the first time Indy race cars are being equipped with onboard crash recorders for use during time trials and actual races. The Instrumented Sensor Technology , Inc. (IST) model EDR-3 environmental data recorder was selected by the GM Motorsports Technology Group late last year for installation on all 1993 Indy cars. The recorders were widely used on most Indy cars for the first time during the Indianapolis 500 race in May 1993. They are now being used regularly in all subsequent Indy car races, including the recent Detroit Grand Prix at Belle Isle, Michigan. The recorder was originally designed for environmental measurement of packaging/handling shock, drop, and vibration.

Selecting a crash recorder

The dynamic environment on board an Indy race car is extreme. The size and weight specifications for any piece of hardware placed in the chassis of the car are of the utmost importance. Before a prospective crash recorder was chosen for installation in Indy cars, it had to be qualified using laboratory crash tests and simulations. Controlled laboratory sled tests and actual automobile crash tests were conducted with the IST recorder at the GM Proving Grounds in Milford, Michigan. Recorder - captured impact acceleration data was then correlated and verified against acceleration data captured by the GM laboratory's standard crash data acquisition system.

GM engineers ultimately chose the IST EDR recorder as a result of its measurement and recording accuracy, as well as its small size and weight, self-contained battery-powered operational capability, and ruggedness. Use of the recorder on Indy race cars will enable GM engineers to more accurately quantify the actual acceleration amplitudes and duration's experienced by race car drivers during crashes.

Accurate crash data will then be used in re-evaluating and improving various safety and design factors associated with race cars.

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