Hello!
I just finished mounting my first quad, and put in (what I think is) a FC with good sensors. On the first flights everything went smooth, the default PIDs were too low but still flyable.
After a few tunings (where I actually ended by doubling all the PID values), I had more confidence and it was real fun!
Then I climbed at the "3 errors altitude" and start doing very cool things in HORIZON mode: sudden turns, and even a looping. Everything was so smooth, and also very reactive. Pure pleasure!
Then I had the bad idea to try how the FC would handle a free fall. I have a switch to activate the MAG and BARO sensors. With these sensors disabled, I put the throttle to 0 (but DID NOT disarm the motors!!) and watched the quad lose altitude, its propellers stopped, then they started autorotating in the other direction. Just after this propellers direction inversion, I put the throttle up again... as only response, the quad flipped upside down!!!!1!
I then switched the MAG & BARO on again, which had no effect. Then, I tried to put it on the good side again, and barely managed to lean on one side. It hit the ground at this moment.
so well... I don't complain about damages. But i'm unable to explain what happened there. Did I do something wrong? I'm totally positive I didn't UN-ARM using the throttle-rudder position.
I'm open to critics. I know I've did something dodgy. But the behavior of the quad finds no explanation in my mind. Are there the behavior limits of the MultiWii? Or is it a known issue (which I doubt)? Or the FC sensors that led MultiWii to mis reaction? Or was it something no-one would ever dare to do?
Vertical crash - please help me to understand
Re: Vertical crash - please help me to understand
Many motor/ESCs have a hard time re-starting the motors in flight, especially if the direction gets reversed.
So ensure that the motors run at idle with the throttle at zero, 1150 is the value I use, if you going to do those types of acrobatics.
Make sure you have commented out the MOTOR_STOP line of code.
Also, do enable the FAILSAFE in the config.h and then setup the failsafe values in the SETTINGS Tab of MW config.exe. Ensure the FS THR is low enough for the quad to descend. This also gives you a box to set the motor idle speed.
I fly ACRO mode only quads for acrobatics and do drop the throttle to zero. With the motors idling at 1150 there isn't any significant thrust and the quad will tumble.
So ensure that the motors run at idle with the throttle at zero, 1150 is the value I use, if you going to do those types of acrobatics.
Make sure you have commented out the MOTOR_STOP line of code.
Also, do enable the FAILSAFE in the config.h and then setup the failsafe values in the SETTINGS Tab of MW config.exe. Ensure the FS THR is low enough for the quad to descend. This also gives you a box to set the motor idle speed.
I fly ACRO mode only quads for acrobatics and do drop the throttle to zero. With the motors idling at 1150 there isn't any significant thrust and the quad will tumble.
Re: Vertical crash - please help me to understand
Hello waltr,
You totally gave me an explanation of what gone wrong!
I wasn't considering the ESCs. As brushless ESCs, they need to detect the rotation. By letting the props spin in the opposite side, it probably led them to power up the bad magnetic loop at each cycle.
I'm glad I've finally found a rational explanation from my crash. Thank you!
You totally gave me an explanation of what gone wrong!
I wasn't considering the ESCs. As brushless ESCs, they need to detect the rotation. By letting the props spin in the opposite side, it probably led them to power up the bad magnetic loop at each cycle.
I'm glad I've finally found a rational explanation from my crash. Thank you!