Hi All,
I have come to pick the brains of all those Crash Investigators following my first Quadcopter crash in over 9 months of flying this model with nothing but perfect soft landings every time!
I was out flying today and this is how it goes:
I'm demo -ing the model to a friend in the garden, in a stable hover about 3/4 meters off the ground - front facing both of us....I've been flying around gently for the last 4 mins.
I walk up to the quad as I have done many times before, tapping the landing skid to demonstrate how it will self
right and stabilise against 'wind gusts'......I've done this loads of times before, with the quad righting itself immediately without even moving.
However, this time it suddenly flips to the front right hand time, and hits the ground upside down (as it was not high).
Luckily nothing damaged, but the clip on battery tray was disconnected along with the battery, and gimbal which likewise flew off.
I have two reasons for flip, obviously either the right hand front motor lost power, flipping the model to the right,
or the front left hand motor flawed it, flipping it the the right. - Either or it must be right?
Now, I have recently put a new set of props on, however they are CF and so I had to make sandpaper washers to prevent the prop from slipping when screwed down.
My only two theories are that either the prop slipped on the right hand side when this happened, but that makes no sense as that motor should have slowed when force applied from the opposite side, not speeding up therfore causing the prop to slip.
Only other thing is it got to angry and flipped on me when knocked in the air by the skid?
Any Ideas?
Has anyone got any advice or tips to post flight checks after the crash before I take off again? I want to identify
the problem before trying to fly to ensure it wont happen again.
Im off now to spool the motors up again and see If they are all working, If so, then it must have been the left side speeding up, to flip it, if not then obviously motor failure on front right hand side.
I'll also check the front right prop to see If it is noticeably loose and able to slip - If so then obviously this is what happened.
My First crash but luckily no obvious damage at the mo, GPS dish even stayed intact!
Thanks all....... :)
Should have seen my face!
If you have an APM FC you can download flight logs and see the performance of the motors. Can you do that ?
Quote from: BigT on August 15, 2014, 09:32:34 AM
If you have an APM FC you can download flight logs and see the performance of the motors. Can you do that ?
Sound like a plan.
Is always happens when you have an audience.
I'm demo -ing the model to a friend
There`s your problem right there,happens all the time ;D
Sounds like a prop slipping to me.
QuoteI have come to pick the brains of all those Crash Investigators following my first Quadcopter crash in over 9 months of flying this model with nothing but perfect soft landings every time!
I find that incredible. I crash and rebuild every week without fail. I must be doing something wrong.
Oh yes, I'm flying manually.
Just wanna say that approaching your flying quad to tap it doesn't sound like the smartest of ideas.
You get bitten by that prop you won't ever do it again. Good luck with the crash investigation though, it always sucks when you don't know why.
One of the fundamentals of crash investigation is identifying the equipment in use. Any clues????
This is not me being picky, because it may be a reported problem with a particuler quadcopter or flight controller.
Thanks for all the replies!
I'm always cautious when approaching props, Ive had my fair share of cuts and bruises from them!
Luckily it literally flipped on the spot and hit upside down/....so was no where near me by the time I jumped back in shock!
I am using the Naza M lite as Controller.....not sure if you can download logs from that.
Prop was tight when I checked after the crash, I couldn't budge it with my hands no matter how hard I gripped the motor and twisted the prop.
Thing is If I were tapping the front left hand side (looking at quad from back) then the LH front motor would speed up to compensate right? If this increase caused a slip in the prop on the LH front motor, it would lose lift that side and dive to the left right? But the thing was it tipped/rolled to the right front hand side.
This front RH motor should have slowed at the time of the tap, and so I doubt that slowing would cause that prop to slip and lose lift to fall to the right? Is that possible that a reduction in RPM would cause the prop to slip?
I have yet to test the motors as I am now away, it could turn out the RH front motor failed but I will not know that until I test them...no bent motor shafts or broken props though so hopefully they run true and fine.
The props seemed all normally tight when putting an allen key to them to tighten (which I do before every flight due to the worry of them slipping due to the set up I have)....and so I am seeing the prop slipping theory as a very unlikely one.
My bets are with the motor failing on the front RH side, or for some reason the front LH side motor for some reason going flat out in some sort of malfunction.
Is a possible theory that the Naza M just got angry with me and over corrected when the tap occoured? Then flipping over as perhaps it was stronger than any wind gust and it couldnt cope with its programmed parameters?
Trying to narrow it down, testing the motors when I get back will help rule out the Front RH side failing or not (unless
it was momentarily and is now working again).
John :))
Thanks so much!
Nervous to fly again until its figured.
And yes, I always fly in GPS/Attitude so have never had a scratch in 9 months of flying every week at least! :D
possible loose wiring connection? this has been reported about DJI ESC to motor connectors.
Quote from: electrotor on August 15, 2014, 01:21:41 PM
One of the fundamentals of crash investigation is identifying the equipment in use. Any clues????
This is not me being picky, because it may be a reported problem with a particuler quadcopter or flight controller.
Well said!
Definitely not slipping prop, highly unlikely to be a software bug, faulty motor very unlikely, bad connection - possible, faulty ESC - likely suspect - you get what you pay for however standard DJI Opto 30A ones are very reliable but can't see which ones you have (not that I'm an expert on ESC types).
Yep, I agree I doubt it was a slipping prop.
I'll test the motors when I get back, but If this helps I was using 30A SimonK Flashed ESC's with the T-Motor
MN3110-700Kv Motors with a 14.8V 4S.
Parameters on my quad are set very low, so do you think a NAZA response or over correction, pushing out
of operating parameters it got p*ssed off and went for it?
John. :D
^^ProFlight 30A SimonK Flashed ESC's (x4)
Hi All, Sorry for the late development/Post!
I have now gone ahead and powered up my quad for the first time, and can confirm all motors spooling up fine,
Including the Front right hand motor which I had my eye on!
This almost turns things on its head, and the only theories I have are below:
1) Prop Slipped on FR (Front right), losing power flippin gquad to right - Unlikely now as I checked all props were tight
after flight, but still a possibility with my set up
where props have little grip (CF Props on
sandpaper washers to add grip)
2) FR motor failed - Odd now though as in test it is running fine after crash, unless something came loose in flight
but is now connected.
3) My only Idea Left of to what caused this;
Naza M Lite got angry when I pushed the quad, flipped out and over corrected/movement went outside its parameters? A little like how a Gimbal will shudder shake when you flip it upside down? Couldn't calculate the sudden aggressive knock like hitting a solid object?......although I've tapped it in the air numerous times before hand with normal corrections.....
My only other idea is something onboard striked the prop.......I've got no idea what else could possibly cause such a sudden and violent reaction that overturned the quad without barely losing a meter (That quick!).
If I cant find the cause Im a little worried about flying again, in case it happens whilst in the air.........anyone got
any advice or things to test/check before trying to take it up again, post crash kind of stuff? Im terrified. :(
Thank you all so much.....Hopefully I will get confidence back with reassuring advice?