T25 VTOL R & D Record 6 - Good things, start again!
Recently, the dynamic of T25 has not been updated, and it was intended to show the phased results, but it has encountered a series of problems. Facing and solving problems is part of research and development and needs to be documented for more people to refer to.
Fault 1: Multi-rotor electric modulation
Dshot mode startup failed This plan to use electric modulation Dshot to check the motor speed, configuration occasionally found the motor does not turn the problem, did not attract enough attention. Causing more serious problems in outdoor testing, I used to switch to automatic mode first, then unlock, but the right front motor didn't turn, the other three motors turned, and the plane went straight to the right front on the ground.
If you unlock it first and then switch to the automatic mode, you can find whether the motor idle turns during the unlocking process. Dshot mode is not recommended for the time being because of its low reliability. Later, DroneCAN electrical survey is planned to check the speed.
Fault 2: multi-rotor electric regulation accidentally short-circuit burned
When preparing to test the endurance of 5KG load, just as the motor idle speed was unlocked, the electrical short-circuit caused sparks and soon burned black. Some inspection found that the carbon plate under the motor base wore out the positive electrode and phase line of the electric regulation, resulting in short circuit in the electrical regulation work. Because it is not a finished electrical adjustment, it took 2 weeks for the electrical adjustment to be replaced.
Fault 3: Fixed-wing switching multi-rotor return stage aircraft pitch swing
Before pitch swing has been considered to be the problem of braking force, return distance and PID of multi-rotor pitch axis, the parameters that can be adjusted have been moved again, but the improvement is not obvious. Finally, it is found that the airspeed meter is affected by the multi-rotor airflow, and the fluctuation of airspeed causes the fluctuation of pitching attitude. This problem can be solved by temporarily placing the airspeed meter in the nose, which is less disturbed by the multi-rotor airflow.
Fault 4: Turning causes compass change and EKF bursts red
The machine did not find this problem before, it appeared after replacing the electrical adjustment, and the recalibration of the compass did not improve. Finally, the three phase lines of the tail push electric modulation are stirred into a strand, so that the magnetic field changes caused by the incoming and return currents are offset. Test flight again compass normal.
Fault 5: T25 crash process analysis
Stage 1: After the airspeed is installed in the nose, the airspeed is greater than the low speed, causing the aircraft to protect at low speed. The reason for the preliminary analysis is that the airspeed meter is only connected with the dynamic pressure tube, and the static pressure is better sealed in the cabin, causing the pressure error.
Stage 2: The static pressure tube and dynamic pressure tube of the airspeed meter are connected at the same time, and it is found that the airspeed increases very slowly, and the ground speed is much larger than the airspeed, which is a high probability that the static pressure tube is affected. The emergency took over the multi-rotor fixed-point mode, but the airspeed fluctuated greatly, causing the pitch attitude of the aircraft to fluctuate greatly, which was difficult to control, and finally crashed into the iron roof of the abandoned factory, falling apart.
T25 Phase I summary and phase II outlook
Although the battery life of T25 phase I has not been tested yet, we have roughly verified the aerodynamic efficiency of the foam wing, deeply understood the difference between the theoretical strength and the actual strength of the foam machine, and also received a lot of suggestions and feedback from friends who care about T25. We will incorporate the lessons learned from the first phase into the second phase of the T25 testing machine. T25 phase II adopts inverted T-tail design, 3.2m wingspan, 12S power package, uses 4 6S30000mah solid-state batteries, estimated load of 3KG, endurance of 250-300KM, the maximum load can reach 5KG, folding tripod, the maximum length after packing does not exceed 1.5 meters. Good things take a long time, we start from the beginning, stay tuned.
