As for air drag above read rolling resistance and velocity and multiply them together to
obtain the power used. Graph power against time and again the area under the graph is
the energy used in overcoming rolling resistance.
Kinetic Energy:
Can be calculated using the cars final velocity and its mass
Kinetic Energy = ½ x Mass x Velocity squared
Losses in Motor & Transmission:
These are difficult to obtain on their own but are taken care of “automatically” if you like
in that the data on motor performance inputted into the simulator was actual motor power
output for the sun level tested so the motor efficiency was already taken into account (ie.
motor losses) the transmission efficiency is also inputted into the simulator so the Motor
drive force and Velocity from the simulator output multiplied together and graphed as in
Air Drag above give the power to the drive wheel after losses. Losses and unused
energy will make up the difference between the energy used to drive the car and the total
energy available from the panel.
Consider ENIGMA configured with a 6 Volt 2224 Faulhaber motor no electronics and
powered by a solar panel producing 6 Watts. Using the Simulator and data from the
Dynamometer testing of motors the following has been calculated for a race.
Total Energy available from the Panel over the race duration 114.6 Joules
Total energy the motor could have delivered to the drive system
if it had been fully loaded at its most efficient operating point
for the entire duration of the race. (presently impossible) 87.8 Joules
Which is only 76.6% of the total energy available from the Panel.
Energy actually delivered by the motor during the race 59.0 Joules
Which is only 51.4% of the total energy available from the Panel.
And only 67.2% of the total energy available from the motor if it
had been fully loaded at its most efficient operating point for the total
race duration.
The energy the motor delivered was split up in the following way expressed as % of total
panel energy available over the race duration
Air drag 13.0 Joules 22%
Rolling resistance 18.3 Joules 31%
(Split 10.3 J to wheels and 8 J to guide rolls)
Car Kinetic Energy 27.7 Joules 47%
** Both increase with increasing car Mass