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ALMS: Sebring Radar Speeds and Sector Times
Written by: Marshall Pruett   
03/14/2008
Sebring, FL
 
We broke down the most telling areas of the track (red dots) and captured radar and sector time data to reveal how cars in the four different classes compare. (Photo: Courtesy of Sebring Int'l Raceway) » More Photos


By Marshall Pruett and Sam Collins

I love using radar guns. One of my duties as a junior engineer in the former Indy Lights series entailed capturing radar speeds of the important cars in the field, comparing those to our own speeds, and offering analysis of how and why our cars differed. I’d also use a stop watch to capture sector times—the recording of specific times cars take to negotiate important sections of a race track.

While on-board data acquisition systems provide immensely powerful data for engineers to use, I remain a big believer in wandering out to key corners and gathering data the old fashioned way (OK, like we did in the early ‘90’s…)—with a stopwatch, a radar gun, a pen, and a note pad.

Sometimes watching a computer screen just can’t compare to going out and watching the cars live and at speed.

With sector times and trap speeds in hand, one can deduce comparative levels of aerodynamic downforce and drag along with outright pace through a timed sector. Add in a trained eye, and you can pick out the damping and springing differences between cars. Lend a trained ear and you can discern how a driver is using the throttle or brake, and how long a driver uses those pedals.

I’ll be bringing my radar gun and stopwatch with me at each round of the American Le Mans Series in 2008 and to France for
the 24 Hours of Le Mans—breaking down the differences in performance between the cars and offering insights on where their strength and weaknesses are should provide a greater understanding of the incredible performance capabilities in every GT and prototype in the field.

Introductions aside, here’s what Sam Collins from Racecar Engineering and I found in the first few official practices at Sebring—with Sam manning the gun and watch, I kept an eye out for handling traits and trends. Sam’s data and subsequent analysis is incredible. Of particular interest, we wanted to measure raw accelerative speeds and chose to shoot trap speeds where the cars reached maximum velocity before slowing for turn one, and also captured their speed at the apex of turn 16—the corner leading onto the long back straight.

To shed light on how much steam the cars made, we then walked down to turn 17—the end of the back straight, and recorded the top end speeds of the cars.

Finally, we wanted to time the cars through a monster turn, and at Sebring, turn 1 is where the divining of the brave and the not so brave takes place. Our sector times were recorded from the point where drivers began turning into the corner to the edge of the outer curbs at corner exit. To compliment the turn 1 entry top speeds he recorded, Sam also logged the subsequent drop off in speed at the apex of turn 1.
We broke down the most telling areas of the track (red dots) and captured radar and sector time data to reveal how cars in the four different classes compare. (Photo: Courtesy of Sebring Int'l Raceway) » More Photos

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