# Changing the Formations of Unmanned Aerial Vehicles
## 5 In-Flight Testing  
An essential aspect of performing tasks by UAV formations is adopting a configuration tailored to the task at hand. While the formation is in transit, the adopted arrangement should be characterized by the dispersion of aircraft to avoid collisions between them. Conversely, the take-off and landing maneuver should involve a higher concentration of aircraft, resulting in a limited area for the deployment of the aircraft. Additionally, during search operations, formation flight may require a denser configuration, especially during precise searches at low altitudes. A similar search operation, aimed at roughly covering a large area, may necessitate loosening the formation to increase the area controlled by the formation. During verification tests, maneuvers were conducted to change the formation from a line to a wedge/triangle and vice versa. A line formation is characterized by the elongation of the formation unlike in a wedge formation. A line formation is shown in Figure 16. UAV number 1 in Figure 16 is the commander of the formation. The UAVs from numbers 2 to 6 are members of the formation. The triangle formation is depicted in Figure 17. The UAV IDs are the same as in the line formation. The formation commander (ID 1) has not changed position during the reconfiguration of UAVs from the line formation to the triangle formation. Figure 15: Movement to successive positions in the formation. The transition from a line formation to a triangle formation is illustrated in Figure 18. There is depicted the first step. All UAVs form a line formation, stabilizing their positions and altitudes. Next, the UAVs disperse by changing their flight altitudes (Figure 19). This maneuver ensures the safe operation of the system. The UAVs have different vertical positions, preventing collisions during the transition to the new position. The altitude change is presented in Figure 20 and the vertical speed in Figures 21 and 22. Vertical speed is measured within the NED coordinate system, so negative speed indicates an increase in the altitude (Figure 21). In the next step, UAVs move to new positions (Figure 23). The airspeeds of the UAVs are shown in Figure 24 When the UAVs reach the desired positions, they return to the operational altitude. Figures 18 and 22 depict the vertical speed and altitude change as the UAVs complete the transition from a line formation to a triangle formation. The outcome of the maneuver is presented in Figure 23.  
Figure 16: UAVs organized in a line formation. Figure 17: UAVs organized in a triangle formation. Figure 19: Change in the altitude of UAVs—the last step of reconfiguration from the line to the triangle formation. Figure 20: Change in the altitude of UAVs—the first step of reconfiguration from the line to the triangle formation. Figure 18: The transition from a line formation to a triangle formation. Figure 17.0 The result of formation reconfiguration from line to triangle. Figure 17.1 Change in the vertical speed of UAVs during altitude increase. Figure 17.2 Change in the vertical speed of UAVs during descent. Figure 25 presents all altitude changes recorded during the verification tests. To alter the formation's configuration, successive unmanned aerial vehicles were sent to different altitudes. For the sake of software simplification, the changes in altitude were associated with the individual drone numbers. The altitude change related to reconfiguration was calculated such that each drone increased its altitude by two meters relative to the previous one. For example, the UAV with ID 1 increased its altitude by 2 m while the UAV with ID 6 increased it by 10 m. The changes in vertical and horizontal speed recorded during the test are presented in Figures 26 and 27. Figure 17.3 Change in the horizontal speed during the change position (Figure 9)—the second step of reconfiguration from the line to the triangle formation. Figure 17.4 Changes in altitude of UAVs during multiple changes in flight formation.