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First quad unexpected acrobatics. (Magic smoke/broken arms)

#1
Hey guys,

Been lurking the forums for a few days, yall have a great community. Flitetest is one of my favorite youtube channels… often catch myself watching flying toasters and insect-like rubber band planes slowly circle around the room when I should be sleeping. (I also want Josh to drop that Pepsi can) The stuff they do is fantastic and they constantly reference these forums as a leading pool of knowledge for rc flying so here I am.

About two months ago I got my first ever rc anything into the air, here’s the loadout

Hobbyking sk450
CC3D flight control board
Turnigy 3300mAh 3S 30C
Turnigy 9X tx/rx
Hobby King 20A ESC 3A UBEC
SunnySky X2212-13 980kv

loadout website: http://myfirstdrone.com/build-your-first-quad/

First flight was in my room, broke a light bulb, a blade, and scratched the ceiling. Flights 2-10 were in a dusty parking garage where i flew into a brick wall at near full speed, turned the attitude up on the board so I could do “blade drags” with the 10” apc props on the ground if i changed direction fast enough, discharged the battery till the blades stopped spinning… I did not treat it well (got 14 broken blades 8-10” here)... yet for a while it flew amazingly. Took it in a big field and zoomed out past 100m line of sight no problem. Lots of power, ~13-15 min flight time, very stoked, began looking into fpv systems. Around flight #15 is where the uncontrolled acrobatics started happening…

After some time (~30 seconds) hovering, the quad would violently flip and land on the ground. After righting it and picking the dirt out of the propellers/engine bells, it could take off then flip for no reason again… I noticed that engines 1 & 2 were making grinding sounds and sometimes would be hard to turn using fingers. Took of the c-clamp… opened em up… noticed flakes/shards of silvery, magnetic material on the inside of the outrunner magnets… removed the material with a toothbrush… reassembled… grinding greatly reduced… armed CC3D… throttle… esc 1 produced two large sparks followed immediately by thick white smoke.

Did my engines seize and cause my quad to fall from the sky? Did i reassemble the engines wrong? Could it be the tx/rx? I'm thinking of getting four new engines with 30A ubec’s and treating the quad much better this time. For Christmas i bought the dominator v2’s, a new pulse 3300 3s 35c, and the DJI 450 flamewheel frame so I want to diagnose the flipping problem and fix it before I break any new things. Any input is greatly appreciated.

Thanks for listening,
newpilot01

Inside of engine 1 before the metal shards were removed.
sunnkysky 980 shards.jpg

My new tricopter post unexpected acrobatics (fixed the arm with cotton+JB weld)
tricopter.jpg
 

nilsen

Senior Member
#3
Hey there, welcome to the Forum!

If you hold a motor and throttle up and the power cannot be dissapated as rotation you will either a. destroy the motor or b. destroy the esc but most likely both.

I would imagine that the bearings and motors had junk in them from your dusty, muddy, sandy antics and thus they were seizing intermittantly which caused the first crash.

The secont time it was most probably that it was seized or that a coil had shorted and thus your ESC went poof.

These things are tought but they are still spinning parts and need to be treated with respect to get the life out of them.

A side note, every time you discharge your battery below the lipo "safe" minimum (3.2V per cell min min min) you are reducing the life of the battery, you won't notice immediately but silly things like massive voltage drops while giving full throttle and such things will start happening.

Good luck and enjoy!
 

cranialrectosis

Faster than a speeding face plant!
Mentor
#4
Welcome to the forums Newpilot01.

Conjecture at this point is simply that. Vibrations from sandy motors have knocked my copters out of the air by flipping them without warning and motor seizures can fry ESCs. I find it suspicious that after the motors were cleaned out and spinning freely again that the sparks flew. That makes me wonder if bullets were touching or polarity had been reversed to the ESC or motor mounting screws were touching the stators inside the motors.

Any way you slice it, there was fire and smoke and your copter is grounded and the smell lingers for days. :black_eyed:

Sucks. I have been there many times with KISS ESCs and I now use a tool to prevent exactly this.

Build a smoke tester and use it after EVERY crash and before you power up for the day. Several folks chimed in with this suggestion and there are a few photos and links to tutorials to show you how to build this on the page I linked to.

Once you have this built, use it to test for shorts and other blue spark and smoke causing issues before you go full power.

Nilsen is spot on about treating the lipo well. Part of your problem could have been caused by a lipo that was sagging due to being pushed too far too often. Funny stuff happens when your components are drawing more power than the lipo can supply.

I hope you post photos and video of your copter when you have it rebuilt. FPV in a parking garage looks like a ton of fun.

Good luck!
 
#5
Welcome to the forums Newpilot01.

Conjecture at this point is simply that. Vibrations from sandy motors have knocked my copters out of the air by flipping them without warning and motor seizures can fry ESCs. I find it suspicious that after the motors were cleaned out and spinning freely again that the sparks flew. That makes me wonder if bullets were touching or polarity had been reversed to the ESC or motor mounting screws were touching the stators inside the motors.

Any way you slice it, there was fire and smoke and your copter is grounded and the smell lingers for days. :black_eyed:

Sucks. I have been there many times with KISS ESCs and I now use a tool to prevent exactly this.

Build a smoke tester and use it after EVERY crash and before you power up for the day. Several folks chimed in with this suggestion and there are a few photos and links to tutorials to show you how to build this on the page I linked to.

Once you have this built, use it to test for shorts and other blue spark and smoke causing issues before you go full power.

Nilsen is spot on about treating the lipo well. Part of your problem could have been caused by a lipo that was sagging due to being pushed too far too often. Funny stuff happens when your components are drawing more power than the lipo can supply.

I hope you post photos and video of your copter when you have it rebuilt. FPV in a parking garage looks like a ton of fun.

Good luck!
That isn't the correct link,is it? Aren't you referring to the automotive light as fuse?
 

cranialrectosis

Faster than a speeding face plant!
Mentor
#6
On that page there are several links to building a smoke tester. Jhitesma embedded a video. Jipp a link and there are a few photos.

Find one of them that suits you and build it. And yes, it requires an automotive 12v light bulb. :)
 
#9
Welcome to the forums Newpilot01.

Conjecture at this point is simply that. Vibrations from sandy motors have knocked my copters out of the air by flipping them without warning and motor seizures can fry ESCs. I find it suspicious that after the motors were cleaned out and spinning freely again that the sparks flew. That makes me wonder if bullets were touching or polarity had been reversed to the ESC or motor mounting screws were touching the stators inside the motors.

Any way you slice it, there was fire and smoke and your copter is grounded and the smell lingers for days. :black_eyed:

Sucks. I have been there many times with KISS ESCs and I now use a tool to prevent exactly this.

Build a smoke tester and use it after EVERY crash and before you power up for the day. Several folks chimed in with this suggestion and there are a few photos and links to tutorials to show you how to build this on the page I linked to.

Once you have this built, use it to test for shorts and other blue spark and smoke causing issues before you go full power.

Nilsen is spot on about treating the lipo well. Part of your problem could have been caused by a lipo that was sagging due to being pushed too far too often. Funny stuff happens when your components are drawing more power than the lipo can supply.

I hope you post photos and video of your copter when you have it rebuilt. FPV in a parking garage looks like a ton of fun.

Good luck!
thanks cranialrectosis... i'll look into making that tester and my new 3300 will be treated much better :) hopefully the flips and stuff were being caused by the esc's or gummed up engines
 

PsyBorg

Wake up! Time to fly!
#10
Sounds to me like when you cleaned the insides out somehow the coating on the coils was worn thru by the cleaning process or by the material you removed and caused a direct short to the magnet / bell side.