Racing tanks: What a concept! If you're ever really bored and need an excuse to haul out your radio-controlled tanks for a serious purpose, this exercise may be for you! The calculation isn't rocket surgery, but I prefer to figure out something once so that I can avoid taxing declining brain cells in the future. Putting this on the web assures me that I won't have to search for the scrap of paper with all the scribblings later.

To calculate the scale speed of your RC tank, you'll need a stopwatch and a measured "racing lane" with a start and a finish line (10 feet is good). Give your tank a running start to get it up to speed, and time its travel from start to finish. Input the time in the calculator and press "Calculate". These things work best if you take several readings and average them.

This handy-dandy calculator (which is nearly identical to the one that I made for slot cars) is hard-coded for 1:16 and 1:24 scale, two popular RC tank scales. Arbitrary default length and time values are filled in, but you can change them. The "1:1 Scale Miles/Kilometers" info probably isn't very useful to RC tankers; it tells you how long your measuring track would be if it were scaled up to full size (at 1:16, 330 feet = 1 mile). This is something that slot car track owners might be interested in, but not RC tankers, so I removed the interim rounding function to fix rounding errors in the final MPH/KPH conversion.

This video from IMPACT shows the data collection part of the speed test. Using that video's distance and time measurements (3 metres = 9.84251969 feet) plugged into the calculator tells you:

• Test #1: Jagdpanther with stock Tamiya transmission
  3.2 seconds
  scale speed: 34 mph (56 kph)

• Test #2: Impact TU3 with drop down gear
  8 seconds
  scale speed: 14 mph (23 kph)

• Test #3: Impact TU3 with drop down gear and hop up gear set 2
  5.1 seconds
  scale speed: 21 mph (35 kph)
  

--10/29/09