Quadcopter flips after crash

Hi i recently build my first quadcopter and made quite some rookie mistakes. But i'm a bit stuck at the moment and i hope someone could help me.

So after i build it and hooked it up to cleanflight i found out i had put all my motors in the wrong direction. After moving all the motors to the right place and make sure the failsafe was right and stuff i was excited to fly.

So on a windy day (yes i know, i read it everywhere don't fly on a windy day especially when it's your first flight) i went out to fly. On a local dirtbike track i waited for the wind to calm down a bit and then started up my quad. Crazy enough it actually flew, it came a meter of the ground, i was able to fly it forward a bit and turn.

That was the end of the good part because after about 15 seconds it suddenly crashed. I found out that when i switched the motors i didn't switch the uhm... motor shafts? so the motors weren't self tightening anymore and one of the props came off during flight. 

When i came back home i made sure the motors were self tightening, put a new prop on and was ready to try and fly again. For my second attempt i went to a grass field since it would be a softer landing in case i crashed. When i took off on the grass field the quadcopter immediately crashed. it went up for about a meter and then just flipped. I tried again, and again... but it just kept flipping over. Got back home and tried figuring out what was wrong.

So i checked:

- If all motors were spinning in the right direction

- The motor numbers corresponded to the motor numbers in cleanflight

- Re-calibrated the ESC's

- Checked all the props were spinning in the right direction

- Checked if the props weren't upside down (letters facing up)

I wasn't able to find what is wrong with it, i did find something that changed since the crash but i'm not sure if it is what makes the quad flip. When plugging in the batter the ESC's beep and all motors sort of uhm.. tick? i guess this has to do with calibrating them on startup. But one of the motors ticks less than it used to. I recorded it and i'll put the video below. The motor i'm talking about is the bottom-left one. the one with the broke prop.

So to make this long story short:

Did i break my motor? Do i need to buy a new motor? Or what else could be wrong?

I hope someone can help me, i'm kinda stuck at the moment, thanks in advance :)

The video

P.S.

A small question :P i read the receiver antenna's should be in a 90 degree angle. i put my antenna's in a bit of an alternative position i guess by putting one behind my recording camera across the frame. and putting the second one parallel to the fram underneath the battery. This way they are in a 90 degree angle, but probably not in the most optimal position for receiving. Could this be a problem in the future?

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Replies

  • Hi Erwin, Your video doesn't show the motors actually spinning. If any one of them is rotating in the wrong direction all you need to do is switch any two of the 3 motor leads.

    The other thing I would double check is that your motors are connected to your FC in the correct order - i.e. output #1 connects to motor #1, etc.

    • Hi Crady,

      Thanks for your reply :P

      All motors do spin in the right direction and are connected in the right order to the flight controller. I checked this by going into cleanflight and increasing the throttle of each motor seperately and seeing if the right motor turned on and was spinning in the right direction. 

      So my quad is configured with this setup: Screenshot cleanflight

      Edit: Ooh i forgot to mention yeah the video is there to show if this is normal behaviour when plugging in the battery, the do all spin

      • I would start by re-doing your ESC calibration then test each motor's throttle range in CF.  If they all seem to be equal then you can cross that off your list.

        Flipping over immediately on takeoff is nearly always the result of crossed motors or a motor that is spinning in the wrong direction and/or has the opposite prop that it should have - this is assuming your motors are good and your ESCs are calibrated. If you can absolutely rule out those possibilities then it's time to review your flight logs.

        If you're using a NAZE 32 with the latest rel. of CF then you should be able to use the NAZE's onboard memory [in lieu of a micro SD card writer] to store the log by.  In CF, enable Blackbox from the Configuration menu followed by a Save and Reboot. Once that's done click on Blackbox in the sidebar menu then select On-board dataflash chip and 1/32 (3%) for the iteration speed, followed by another Save and Reboot (the slow iteration rate is to keep the onboard memory from filling up too quickly.)

        After you make another flight attempt you can retrieve and save your logs by re-visiting the Blackbox menu. After that you can review your logs by downloading the Blackbox Explorer app.

        • Hey i had time to quickly re-calibrate the ESC's and test the motors in cleanflight. i also double checked if the motors were connected to the right channel and were spinning in the right way. I did notice that they do not all start exactly at the same time. i think one started at 1187 and the last one at 1200, is this a normal difference? is there some normal error or should they all start exactly at that one value?

          If so, how do i do this since i re-calibrated them before testing this out?

          • There are several things you can do to ensure your motors all start at the same throttle level but one of the simplest is within CF.

            With the props removed, connect your battery and then connect to CF.  Under Configuration, turn off MOTOR_STOP and ONESHOT (you can re-enable those after everything is calibrated if you want those features and your ESCs support ONESHOT) and set Minimum Throttle to something low like 1050 and set Maximum Throttle to 1900 or 2000. (The Middle Throttle value should be the actual value your Rx sees when the throttle is centered and is ideally equal to Max - Min / 2.)

            With your Tx off (or at least the throttle at 0), go to Motor Control and tick the switch to enable motor control and do the ESC calibration routine.

            Once your ESCs are calibrated click on the Master throttle and use the UP arrow on your keyboard to slowly raise the throttle value. Record the point at which 'all' your motors begin spinning and add 10 or 20 to that value. This is the new Minimum Throttle value to enter on the Configuration page.

            Continue increasing the Master throttle until all the motors are spinning at maximum and add 10 to that value. This is the new Maximum Throttle value to enter on the Configuration page.

            A good tutorial ESC calibration under CF is available here:

            https://youtu.be/csCBMF8P3qg

            • Thanks so much!!

              It seems to be a calibration issue. I guess the calibration i did didn't work or was faulty, after following the calibration in the video all motors went on at the same time. Just took it out for a flight and it works perfectly!

              Thank you for your help :D

              • Hey!  Glad you got it sorted, Erwin. =)

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