Situation:
To be completed next are a series of test over the types of materials to be used, coasting versus power braking, and the wind tunnel. Materials testing will be conducted to make sure the AEV is made out of a material that is durable as well as light. Paper, rubber, plastic, and metal will be tested for tensile strength and the coefficient of friction. The proven optimal material will replace either the arm, the main support structure holding the Arduino, propellers, and arm, or both. Tensile strength will be used to determine maximum load, work at maximum load, load at break, stress, strain, and Young’s modulus. To test tensile strength, each material will be cut into even rectangles (if possible), weighed, then hung up by one end. The other end will have weights attached. The resulting data collected will be used to form a graph that displays the amount of weight added versus how far the material displaced in the y-direction. This data will also be used to find Young’s modulus by plugging the data into a series of related equations to find stress and strain, then graphing stress versus strain. The coefficient of friction will be used to determine the static friction and the kinetic friction of the material when in contact with the rails. This is especially important for knowing how much energy needs to be put in to start to AEV moving and breaking the AEV once it is in motion. To test the friction of the material, each material will be of equal weight, then placed on an adjustable ramp. The ramp will be raised until the material starts to slide, then the angle, length, and height of the incline will be measured. The coefficient of friction, both static and kinetic, will be graphed versus the material type.
The tests over coasting versus power braking will reveal the method that conserves the most energy and allows for the greatest consistency in deceleration displacement for the AEV. Two separate codes will be prepared, a power braking code and a coasting code. Using the coasting code, the AEV will travel a fixed distance and speed before the motors are to shut off. The total distance traveled after the fact and power use will be measured. This will be repeated up to 10 times. After the last test, the battery will be replaced and the procedure will be repeated with the power braking code. Different motor speeds will be tested as well. Data collected is the mean and standard deviation of braking distance, mean value of power expenditure, the average distance the AEV needs to stop before the gate, and the percentage of runs that fall within the margin of error calculated for each deceleration method.
The tests using the wind tunnel will be used to determine the efficiency of the propeller. Four different propeller combinations –the 3030 pusher, the 3030 puller, the 2510 pusher, and the 2510 puller— will be placed in the wind tunnel. The power sent to the motor will be set at 60%, then, using increments of 5%, the power setting will be decreased to 10%. At each increment, the percent power, current, thrust scale reading, and RPM will be recorded. Using the data collected, calibrated thrust, power input, power available, propulsion efficiency, and propeller advance ratio will be calculated. The data will be also used to thrust versus percent power and propulsion efficiency versus advanced ratio will be plotted. The results will be ultimately used to determine which propeller setup and style is most efficient.
Upcoming Schedule:
During the Advanced Research and Development and Performance Tests that our group will be conducting in the coming labs (specifically Coasting v. Power Breaking, Materials Testing and Wind Tunnel Testing), each group member will continue with their assigned jobs from the start of the semester. These jobs, as well as the development of them, can be found below.
Latia will continue to code for the Arduino by completing both the commands given, as well as further developing a code that will work best for our AEV once we complete preliminary testing. She will also help develop a design for the AEV with Brandon and help with testing.
Brandon will also continue testing the AEV during laboratory periods, as he is the official Tester, and he will also keep working to help the group brainstorm ideas for the best design for their own AEV from the results he obtains during the preliminary tests.
Jared will keep working alongside Brandon during preliminary tests as the Data Collector, making sure everything has been accurately recorded and that all data collected from the lab has been properly saved and uploaded to the website. He will also continue to upload progress report questions to the website.
Madison will continue her role as the Webmaster, making sure the website is always up-to-date and accurate. She will upload meeting minutes as well as the Website Deliverables from each preliminary exercise during lab.
The majority of the tasks outlined above will be completed during laboratory periods, however, if they are unable to be completed, the group will either meet outside of class to finish them or they will finish their assigned task on their own time.
As for materials, the group will need access to the AEV kit, as well as the materials needed for the preliminary tests they chose, as well as the Arduino program and the battery.