Task 2. Collect flight data with Spark in hover.
Fly the unmodified Spark in hover at an altitude between 2m and 3m, recording the RPM of the motors. Measure the RPM using a handheld optical tachometer or an audio-based spectrum app.
Repeat the initial hover tests with weights added to the top of the Spark body with total masses of 10g, 30g, and 50g (or a bit more if these tests go well). Be sure that the center of gravity remains at the center of the drone. Report the measured RPM and infer the value of the thrust coefficient, CT.
- Conducted indoor hover tests in Drone Lab. Recorded motor RPM using the FFT Spectrum Analyzer application running on a Samsung Galaxy S8. For each weight, recorded 5 - 6 discrete measurements. Raw data is attached below in Figure 1.2.1.
- Calculated the Coefficient of Thrust for each weight configuration (neutral CG) using constants in Figure 1.2.2 and weights in Figure 1.2.3. Results attached below in Figures 1.2.4 (Table) and 1.2.5 (Graph). Heaviest configuration tested (138g) depicted in Figure 1.2.6.
- In addition to ballast testing, conducted a tethered test using a spring scale. Spark drone was able to lift 200g / 2N in a hover.
If sensors are available to measure battery voltage and charge, use this to estimate the power, torque, C_Q, and Figure of Merit.
- Independent flight tests were conducted to collect power data in hover with no added weight. Motor speed data downloaded from the onboard computer agree with measured RPM to within 0.5%. Total power draw in hover out of ground effect (2.6m) is 63.5 Watts.
- Data was also collected during max gross hover (513g total). Hovering out of ground effect (2m), the total power draw was 132 Watts.
- It was observed that surprisingly the rear motors draw 14% more current even when the RPM are equal.
Task 2. Collect flight data with Spark in hover.
Repeat these hover tests with added weights offset from the original center of gravity by varying amounts. Note that moving the center of gravity too far will make it impossible to hover so start with small offsets. It is up to your team to decide how to mount the additional weights, but make sure they are rigidly attached (no hanging, swinging weights).
- Conducted hover tests with two varying gross weights (354g and 404g) while varying CG from 0.0cm to -2.17cm longitudinally, and 0.0 to -1.18 laterally.
- Spark configuration depicted in Figures 1.2.7 and 1.2.8.
- Raw data, calculated CG, and CG limits at which the Spark requires manual flight mode to launch depicted in Figure 1.2.9.
- The CG tests are graphically shown along with each of the trials in Figure 1.2.10.
Record the position of the weights and the position of the c.g. (may be measured or computed).
- Repeated 354g gross weight tests using both acoustic and visual measurement tools to determine motor RPM. Raw data is presented below in Figure 1.2.11 (Table) and 1.2.12 (Graph)