Backwards Looking Summary
Situation
In lab 2, the propeller efficiency and the wheel sensors were tested. A sample AEV was also made. The propeller efficiency was tested to determine what level of power they were most efficient at. The propeller was tested by a wind tunnel. The power output was decreased from 60% to 0% power and the propeller was found to be most efficient at 15% power. Next, the wheel sensors were tested to determine how the sensors worked and how to program the sensor calls. The sample AEV was made and the wheels and sensors were both attached. These were tested to ensure they worked. Three sensors had to be replaced because they did not work. The code was created and uploaded to the Arduino; however, there was not enough lab time to run the AEV on the track and test the code.
Results and Analysis
The team was able to assemble their sample AEV without major issue, however several of their beginning reflectance sensors needed to be replaced. The team was unable to test their vehicle and code on the real track; however the team was able to test basic commands on a practice track.
The data that was collected during the second portion of the lab will help the team to decide which power settings the AEV should be run at. The smaller propeller was not tested during the lab, however the team had already decided to use larger propeller, as they predicted it would be more efficient. The propeller was most efficient at around 15% power, which is lower than the team thought it would be. Even though it may be the most efficient power setting, it will most likely be too slow for what the team needs. The propeller that was tested in lab was not as efficient as the sample that was given, however, there are a number of variables that were likely not accounted for.
Takeaways
From the Lab 02 experiment the team has learned to calculate the propulsion efficiency of the AEV. This can later be used to determine the most efficient way to run the AEV to use the least amount of power. The design for the AEV will be toward the lighter side so it will not need as much thrust to get it started and will use less power when moving the AEV. From the information learned during the lab, the team will be able to create a basic code to move their AEV around the track and complete its mission.
Tables and Figures
The propeller that the team used was approximately .08 meters and was configured to the clockwise position. The battery was 8.4 volts and the wind velocity in the tunnel was approximately 3 meters per second. Figure 1 shows that thrust and percent power are directly related. Propulsion Efficiency also appears to increase when the Advance Ratio increases, but as the power setting hit around 10%, the efficiency began to decrease again.
| Table 2: Wind Tunnel Data Analysis | ||||||
| Thrust Calibration | RPM | Power Input | Power Output | Power Output | Propulsion Efficiency | Advance Ratio |
| grams | RPM | Watts | Horsepower | Watts | % | — |
| 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 0.822 | 2035 | 0.1512 | 3.24413E-05 | 0.024191 | 15.99964 | 1.114357 |
| 1.9317 | 3113 | 0.3528 | 7.6237E-05 | 0.05685 | 16.11393 | 0.728467 |
| 3.4935 | 4071 | 0.6552 | 0.000137875 | 0.102814 | 15.69196 | 0.557042 |
| 5.343 | 4910 | 1.029 | 0.000210868 | 0.157244 | 15.28129 | 0.461857 |
| 7.4391 | 5688 | 1.512 | 0.000293594 | 0.218933 | 14.47968 | 0.398684 |
| 10.0284 | 6526 | 2.0874 | 0.000395784 | 0.295136 | 14.13892 | 0.34749 |
| 12.741 | 7245 | 2.7552 | 0.00050284 | 0.374968 | 13.60945 | 0.313004 |
| 16.0701 | 7904 | 3.4776 | 0.000634227 | 0.472943 | 13.5997 | 0.286907 |
| 19.4814 | 8562 | 4.326 | 0.000768858 | 0.573338 | 13.2533 | 0.264858 |
| 23.3859 | 9221 | 5.2206 | 0.000922954 | 0.688247 | 13.18329 | 0.24593 |
| 27.126 | 9760 | 6.2496 | 0.001070562 | 0.798318 | 12.77391 | 0.232348 |
Figure 1
Figure 2
Forwards Looking Summary
Situation
In lab this week, the team will be brainstorming ideas for their AEV vehicle. First, each team member will create their own design. Then they will come together to make some preliminary design decisions and agree on a single design to draw isometric views of.
Weekly Goals and Schedule
The team will continue brainstorm AEV designs individually and come together to discuss their ideas. The will start to look ahead at the Preliminary Design Report and continue updating the team website. A more exact schedule of the work needed for the semester will be drafted.
| Date Due | 2/2 | 2/9 | 2/9 | 2/9 |
| Task | Complete Lab 3 | Lab 3 Progress Report | AEV initial designs | Add Lab 2 to the online portfolio |
| Team Members | all | all | all | all |