# Improvement of Hexacopter UAVs Attitude Parameters Employing Control and Decision Support Systems
## 4 Laboratory and In Situ Measurement Results and Discussion
### Online Testing Platforms Results  
In order to find the best configuration to ensure a stable flight with the best range within safe flight conditions, several variants of equipment, including sensors, propellers and batteries, were tested using online platforms specialized in the multirotor drone segment. This section presents the best results for the proposed hexacopter in terms of stability and flight range employing the _xcopterCalc_ simulation platform, one of the most popular tools in terms of configuration simulations for multirotor drones. Similar results for the hexacopter were obtained for both variants, were two different flight controllers and avionics components were employed, Tarot ZYX-M and Pixhawk 1, respectively, as presented above. Figure 16 illustrates the results obtained in variant 1 of the hexacopter, where Tarot ZYX-M flight controller and subsequent avionics components were utilized. The configuration used was as follows:  
* Frame size is 695 mm and is made of carbon fibre epoxy resin with a total mass of only 833 g, while providing increased shock and vibration resistance. * The propellers were 13\" with 5.5\" pitch--the size of the drone frame limits the mounting of propellers with a maximum diameter of 13\". * Four-cell LiPo battery capacity--16 Ah, in 4S2P configuration with 12-24C C-rating, 14.8 V nominal voltage. * Flight testing of the HDT was simulated at an altitude of about 85 m above sea level (Bucharest altitude), at a temperature of 22 \({}^{\circ}\)C and at an atmospheric pressure of 1010 hPa (757.5 mmHg). * Electronic speed controllers (ESC) can withstand a maximum current of 40A and have an internal resistance of approximately 0.0006 Ohm and a mass of 26 g each. * The hexacopter has a three-axis rotating and stabilizing gimbal; it has a mass of 178 g and consumes approximately 0.05 A. * Tarot 4006/620 KV BLDC motors produce 620 rpm/V and have an internal resistance of 0.126 Ohm and a mass of 82 g each. Figure 15: Measurement of motor temperature during operation on the test stand, within 5–100% throttle range. After running the simulation, the following results were obtained, as illustrated in Figure 16.  
The following conclusions were drawn:  
* Load on the battery (load) is 8.49C (which means a continuous load below 12C A of the battery, i.e., 8.49 \(\times\) 16A \(\approx\) 136A \(<\) 12 \(\times\) 16 \(\approx\) 192A). * A considerable increase in flight time to 15.1 min for combined flight and 20 min for hover flight, compared to lower capacity batteries used in previous tests. * For optimum motor performance, a slight increase in efficiency from 84.1% to 84.2% is obtained; for fixed-point flight, a speed of 4116 rpm is obtained. The motor speed increases from 48% to 56% of capacity (which is a good result), a power-to-mass ratio of 151.4 W/kg, an efficiency of 77.5% and a temperature of only 31 \({}^{\circ}\)C. However, as an element to be taken into account, an increase in power (at engine input) to 321.9 W (but only at maximum engine speed) is noted. * The thrust-to-mass ratio in this case is 2.3:1 (>1.8--very good value). * The specific thrust of the propellers is 6.67 g/W, so high efficiency. * Additional equipment with a mass of about 3.6 kg can be attached. Figure 17 depicts two graphs (a) and (b), obtained after running the simulations, showing data regarding flight distance, speed and engine characteristics at maximum speed. The following conclusions were summarized:  
* The maximum speed is 40 km/h, and the ascent rate of 7.1 m/s;
* The maximum flight time (without drag) is about 20 min;
* Maximum flight time (with drag) decreases to 15.1 min;
* The maximum flight distance (without drag) is approximately 7600 m;
* The maximum flight distance (with drag) is approximately 4400 m;  
Figure 16: Results obtained after running the simulation using _xxoperCalc_ platform. Figure 17: Online tests. (**a**) Range estimator; (**b**) Motor characteristics at full throttle.