Abstract
Since the invention of the electric motor in the 19th century, innovations and
technological advancements have come along to produce more output power and
efficiency. The main objective of this laboratory experiment is to study the operating
characteristics of direct current permanent magnet motors using a dynamometer.
Observations are made by running several tests with airplane propellers attached to the
DC motor, recording measurements of thrust, torque, and propeller speed generated.
From these sets of data, the input power, shaft power, output power, efficiency, and
overall thrust per unit of input power can be derived. Studying the results from the
experiment can allow us to make modifications to improve power and efficiency of the
motor and continue on advancing the technology of electric motors into the future.
Experimental Procedures
Equipment:
1. DC motor
2. Propeller
3. Voltage controller
4. 12V battery
5. Torque, thrust, and RPM meter
Figure - Experimental Apparatus (image courtesy of IE 3135 Industrial Engineering
Production Processes Laboratory Manual, 1999, L. W. Garber Ph.D.)
Procedure:
Install the zero-pitch propeller on the DC motor and make a test run at 3V, recording the
armature current and the RPMs. Install the 9D-6P propeller. Starting at 2V, take current,
torque force, thrust, and RPM measurements in one volt increments up to 7V. Repeat this
process with the 8D-6P propeller and the 7D-6P propeller. From the data gathered,
calculate the input power, shaft power, output power, efficiency, and thrust per unit of
input power. Plot these calculated values versus the RPM data collected. Also, plot the
measured RPMs versus the calculated RPMs for each of the three different propellers.
The sole independent variable in this experiment is the amount of voltage supplied to the
DC motor. The resulting dependent variables are amperage, torque, thrust, and RPMs.