React nomadio, User Manual

Page: 71 / 101

Measurement method
In this method, you simply measure the distance traveled by your model over a short
length and count the revolutions of your driveshaft. Due to the possibility of
measurement errors, this method works best if you measure at least ten shaft
revolutions. We recommend that you mark one of your magnets with a colored sharpie
or piece of tape to reduce the risk of incorrect counting. Make sure you are measuring
using the same units (inches or centimetres) that the React is currently set up to use.
Position your car against a wall with the wheels pointed straight ahead. The back end
of the car should be touching the wall.
Carefully watching the magnets on the shaft, roll the car forward until the shaft has
rotated ten or more (more is better) times. The number of rotations will be your
revolutions parameter.
Measure from the wall to the back end of the car. If it should work out to an even
number of inches or CM, that will be your rollout parameter. If your measurement is to
the closest 1/8
th
of an inch, then in order to eliminate the fraction, you must multiply
the revolutions by 8 and convert the length to 1/8
th
inches by multiplying the whole
number of inches by 8 and then adding the number of extra 1/8ths. If you are using
metric measurement, it is simple, just multiply CM length and rollout by ten.
Example: Your model was measured to travel 31 5/8” in 10 drive shaft revolutions.
This is equivalent to 31” x 8 + 5” = 253” in 80 revolutions. Thus, the rollout
parameter in should be set to 253, and the revolutions parameter should be set to 80
The higher the numbers you use, the lower your error will be and the more accurate
your speed will be. The maximum value that can be used is 10,000. It may be more
convenient to enter larger numbers using the Digital RC Desktop software.
Since the tach sensor measures only shaft rotation, it does not take into account other
issues like wheel spin, tire expansion at speed, cornering errors, etc.