The setup:
1. 42’ BestTrack. The 42’ has 4 straight sections, with the timer sitting at the end of the fourth section). Actual running length is 36’ 10 7/8” as measured from the uphill side of start pin to finish line sensor (in last of the punched holes on the track). At each location the track was checked for level at each track joint using a torpedo level.
2. MicroWizard K2 timer connected to computer using serial to USB port
3. Data captured by GPRM version 10 running in Windows 7.
Information about car population:
Data set is comprised of 1,452 runs from 201 cars from 12 different packs. Rules were not consistent from pack to pack, though most used the rules in the box. Packs were consistent in having a 5 oz limit as measured on that Pack’s scale. The population was made up of cars you would see at a typical Cub Scout pinewood derby and included everything from 3-wheel, well-tuned rail riders to cars that had none of the usual speed techniques applied. All cars were gravity powered. There were no razor- or bearing-wheels. Nearly all used BSA wheels, while a small handful used PineCar wheels.
Data was grouped by the hundredth of a second (0.01) by rounding up to the nearest 0.01. A time of 3.2001 seconds would fall into the 3.21 group and a time of 3.1999 would fall into the 3.20 group. Times that exceeded 4.0 seconds and cars that did not finish (DNF) were grouped into the 4.00 group. There were no times in the population that were faster than 3.00 seconds.
The following chart shows the distribution of race times. The most frequently occurring time, or mode, is 3.17 seconds. The mode marked the 90th percentile, meaning that 90% of the runs had a time of 3.1700 or slower and 10% had a time of 3.1699 or faster.
This chart shows where specific times show up in the top 50th percentile. The 95th percentile is between 3.14 and 3.15 seconds, meaning that if your car’s times can beat 3.14 seconds then you are faster than 95% of cars found at a typical Cub Scout race.
Please note that competition in your pack or district may not be that of a typical Cub Scout pinewood derby.
To those who have other datasets, either for BestTrack or other tracks, please share what you have.
