# Integration and Flight Test of a 7 kW Turboelectric Vertical Take-Off and Landing Unmanned Aircraft
## 4 Results
### Uncertainty  
Repeatability of flight tests and associated measurements was limited by the cost and availability of resources. This unmanned aircraft requires several people to safely operate and collect data. Higher accuracy measurements require increased cost and add weight and complexity. The conclusions formulated are based on trends in the data rather than specific values, and trends are more generalizable to other systems. Bias errors for measurements are included in Table 1 above, and are discussed in this section. For the purposes of a paper seeking to identify broad integration issues and trends, measurement uncertainty levels are sufficient to draw conclusions about trends and comparisons.  
For measured current values, two 200 A Mauch power modules were utilized in parallel. The maximum bias read-out error over the full operating range provided by the manufacturer is 1.2% per module. At the maximum-recorded value of 390 A, the modules would have an error bound of 4.68 A. This sensor required manual calibration when first installed, and there could be an associated offset error. Because all measurements were taken with the same sensor, this error would be uniform for comparison purposes. Maximum loads can be distinguished, and significant comparisons can be made over the course of a flight, despite the bias error.  
According to the power module manufacturer, the power module utilizes an 18:1 voltage divider to enable measures up to 14S (60 V) on the 3.3 V Pixhawk analog-to-digital converter (ADC). Because the utilized onboard Pixhawk (ADC) has a resolution of 12 bits, yielding a bias error of \(\pm\)0.015 V over the operating range, there may also have been a small offset error in the voltage sensor because it required manual calibration on installation. However, since all voltages in this study used the same sensor, this offset error is negligible for the purposes of comparison and in the discussion of relative change.  
The airspeed sensor (along with video footage) was used to correlate the different aircraft flight modes. Using the maximum pressure error bound of the sensor along with the definition of dynamic pressure at static conditions (the worst for the measurement) gives an error bound \(\pm\)1.2 m/s. Therefore, there is a large amount of noise in the sensor at low airspeeds. As speed increases this becomes a smaller issue. At the peak airspeed of 20 m/s the error bound is \(\pm\)0.035 m/s.  
The thermocouple temperature sensor utilized in both locations has a maximum bias read-out error of \(\pm\)2 \({}^{\circ}\)C across its operating range from \(-\)40 \({}^{\circ}\)C to 125 \({}^{\circ}\)C. Therefore, the real maximum temperature may have been two degrees higher, but that does not impact the observation that thermal equilibrium was not reached.  
The ICM-20649 accelerometer utilized in this study was embedded inside the Pixhawk Orange Cube, and has a maximum acceleration of \(\pm\)30 g with an LSB of 1024, giving a read  
Figure 12: Acoustic measurements from all microphones during full flight regime.  
out error of \(\pm\)0.001 g according to the manufacturers data sheet. This high level of accuracy is necessary since the flight controller uses the accelerometer for detailed navigation.