Now that the track is build and the racing line is measured I of course want to know how fast my car is. Unfortunately my current webcam based lap counter software does not have a function where it calculates the average speed based on track length.

I posted earlier how to calculate gear ratios and top speed. I also compared  the RPM’s and MPH of Tamiya’s stock motor with a Brushless motor.

Here is the math to figure out the average speed:

Average Miles Per Hour

Average Speed = Total Distance divided by Total Time

D = distance (length of the track) in feet = 130 feet
T = time in seconds  = 14.716 seconds (based on 4 test days and 3 race days)
S = speed in miles per hour

To convert seconds to hours use 3600 (because there are 60 seconds in a minute and 60 minutes in an hour)
To convert feet to miles use 5280 (because there are 5280 feet in one mile)

S = 130 feet / 14.716 seconds = 8.83 feet per seconds

8.83 feet per seconds x 3600 = 31788 feet per hour

31788 feet per hour / 5280 = 6.02 miles per hour

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Average Kilometers Per Hour

Average Speed = Total Distance divided by Total Time

D = distance (length of the track) in feet = 39.62 meter
T = time in seconds  = 14.716 seconds (based on 4 test days and 3 race days)
S = speed in kilometer per hour

To convert seconds to hours use 3600 (because there are 60 seconds in a minute and 60 minutes in an hour)
To convert meter to kilometer use 1000 (because there are 1000 meter in one kilometer)

S = 39.62 meter / 14.716 seconds = 2.69 meter per second

2.69 meter per second x 3600 = 9692.3 meter per hour

9692.3 meter per hour / 1000 = 9.69 kilometer per hour