|Table of Contents
Sources of Error
Note: The manipulation of dependent variables is detailed on the
previous experimental design chart. In total, there were 12 rotor variables
manipulated, using one, two or three rotors, three sizes of DC motor at medium
and high fan speeds. Each variation was tested ten times.
rotor(s) was/were attached to the horizontal axis. The plastic end cap was
placed on the end of the axis.
2. A DC motor (1.5-3 V, 9-18 V or 12 V) was coupled to the other end of the
axis and the leads of the multimeter attached to the poles of the motor using
3. The fan speed was set at medium or high and
the rpm and wind velocity at the rotor end of the axis were measured using the
digital tachometer and anemometer and recorded.
4. Step 3 was repeated a
total of ten times.
5. Ten measurements each of mAmps and mVolts were taken using the digital
6. If the rotor variation failed to start and continuously
turn the DC motor, the rotor variation RPM was equal to zero and testing of that
Caution: The rotating blades could
cause serious injury. Care was taken to ensure that body parts, hair and
clothing were always kept clear of the moving rotors.