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The planned approach was to use the received route information once the QR code is scanned to create a waypoint plan automatically, load it into Mission Planner, and flash it into the flight controller. Once flashed, the aircraft would be armed, take off, and begin the waypoint mission flight. As the drone flew and sent the diversion information, the chosen approach was to create a modified waypoint mission to avoid the exclusion zone and rejoin.
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Overall, Task 1 was not attempted and unsuccessful in reaching any waypoints. Icarus was initially flown in its full quadplane VTOL configuration with wings. The In previous flights, unpredictable motor behaviour was observed where one motor would fail after an arbitrary amount of time. Hence, the team elected to do a motor and hover test from a safe height above the ground to see if the aircraft would be able to sustain flight for long enough, safely, and to ensure motor efficacy since unpredictable motor behaviours were observed in previous tests. The first hover was performed for about 3 minutes, before the rear-right motor (4) failed, causing the drone to come down in a hard landing from a height of about two meters above the ground.
The Analysis of the motor failure indicates that the failure was caused was due to overheating of the motor from running the motor at high power for a prolonged period of time. The flight-line team thereafter removed the wings to reduce weight and tried running a hover-test again to test the motor again. Unfortunately, the same problem occurred and the rear-right motor gave way. Through more investigation and research into motor specifications, it was concluded that the desired flight profile, as a fixed wing aircraft with vertical takeoff capability, was not achievable using the current motors in the given weather conditions, as these motors were intended to run at maximum current for three minutes at a time - not for sustained quad flighttime but we experienced failures far faster than the rated operating time. The team concluded it would be unsafe to transition without further validation of the aircraft performance.
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Remove wings and mid-wing sections
Remove tail-section
Remove pusher motor and prop
Remove all mounting hardware and sensors that were not required for quadcopter flight
The datasheets for the quad motors were examined and it was seen that the motors were not optimized for continuous operation. Since they are VTOL motors, they are designed to be used at very high throttle for short periods of time before the aircraft transitions to fixed-wing operation, and not for continuous quad flight. This issues was further exacerbated by the lack of ventilation on the motors. Hence, it was determined that the motors would need to be changed to motors with lower power draw, increased efficiency and more appropriate duty cycle requirements. New motors, Titan T6015, were borrowed from another team and mounted on the aircraft. These motors are optimized for quadcopters, have sufficient ventilation, and are rated for the required thrust of our aircraft.
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Task 2 models a scenario where various transit routes are givenprovided, and need to be optimized paths between these waypoints are followed, all while picking up and dropping off passengers at numerous given waypointstheir desired destinations. With the same cabin and landing pad used in Task 1, the competitor must carry the passengers and land on the pad with rotors stopped for 15 seconds. A QR code was given that detailed the available routes, and specific routes were to be chosen to fly.
The approach taken for Task 2 was manually determining routes that were close to the starting location and had a short travel distance. These routes were then to be uploaded to Mission Planner and flown with an established geofence.
Aircraft Performance
The aircraft was able to successfully arm without errors on the first attempt. It was taken off in stabilize mode and flew well without excessive vibration. The aircraft was then tested in Loiter, where it demonstrated excellent stability for 3D position hold. After a short hover, the aircraft landed, waypoints were uploaded, and it armed in preparation for takeoff. Following takeoff, the altitude was manually increased to 50 m before the aircraft was switched into auto mode. The aircraft began to fly the mission shown below. Before reaching the first waypoint, the aircraft threw a geofence failsafe and began to return to home. The pilot in command switched the flight mode back to Loiter and attempted to fly down the runway manually. Again, the aircraft hit the fence and entered Return To Land. Return To Land was followed until the aircraft was close to the takeoff location, where the pilot then switched to Loiter and landed via down-facing FPV camera.
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The team instead chose to manually chart a path to optimize chances of safe success rather than for cost.
Routes were chosen manually, and are shown in the diagram diagrams below:
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Conclusion
Overall Performance and Lessons Learned:
Over the course of Task 1 and Task 2, various faults were identified and noted for subsequent years' competitions. The most significant lesson learned from the competition tasks was to keep the drone design simple, test frequently, and to test often, in various test during different weather conditions. The original design of the aircraft was a VTOL fixed-wing hybrid which was optimized for controlled vertical landing on landing pads , as well as long-distance flying between waypoints. However, the drone’s weight of the drone was too high, causing the motors to have to work harder and overheat, preventing the drone from flying longer than three minutes. All of the testing for the was greater than anticipated, and the motors were not able to generate enough thrust for sufficent landing and takeoff times. All testing of the aircraft was performed in the winter with very cold temperatures, so the overheating issues were never encountered by the team. Therefore a valuable lesson learned was to take into account the ambient temperature of the drone when conducting flight tests.
The mass of the aircraft increased much higher than anticipated after integrating systems such as landing gear, control surfaces, video, lights, and GPS. The mass of long cables and solder, as well as tape and hot glue were underestimated causing the overall mass of the drone to be over the 15 kilogram limit when conducting the Flight Readiness Review. Ultimately, designing the competition airframe as a quadcopter would have been significantly simpler, weighed weighted less, and would allow for a larger number of flight tests to tune to drone and practice flying to waypoints and landing on landing pads.
During the Task 2 flight window, radios were used as a method of communication between the flight line and the ground control tent. The radios were unclear and the team resorted to using cellphones to communicate. More testing should have been done on the radios beforehand. The organizational flaw during the Task 2 is that the flight line communications could have been made more clear by using predefined roles and tasks.
Final Comments
Ultimately, Project Icarus attempted both Task 1 and Task 2 of the UAS 2023 competition as detailed in the CONOPS. Icarus went through multiple rapid prototype and development phases throughout the competition, but ultimately all configurations were not able to complete the tasks as expected. Various reasons were detailed and analyzed as to why the goals were not achieved, and takeaways were noted for subsequent competitions. WARG has a lot of points to take back and work on for the drone during next year’s competition season.
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