WKM Crash at takeoff

Mediakopter.no

Mediakopter.no

Member
Today my octo tipped over to the left and crashed at takeoff. It felt like the more throttle, the more the right side lifted. There was no mechanical flaws as I know. Yesterday it flew perfect at the same location. I did the calibration dance yesterday, and not today. The drone was transported in a car to the location. I did not do the calibration dance today.

Could the gyros or acc's be disturbed/knocked off by transportation?

Can the lack of calibration dance today be the cause of the Crash?
 
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Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
Hi mate,

I've noticed sometimes my WKM doesn't initialise properly. The motors don't sound quite right on throttle up. Naturally I don't try to take off when it's like this and just unplug and start again. Could be an ESC not initialising also.

I don't think calibration was your problem. If it looks like it's going to tip over just stop increasing throttle and restart the system. It should take off perfectly.
 

SleepyC

SleepyC

www.AirHeadMedia.com
Also don;t try to fly the take off, in fact keep your hand off the cylic stick. On take off they can rock a bit and if you try to correct, it usually results in a tip over.
 

Mediakopter.no

Mediakopter.no

Member
I doubt use of the cylic stick was the cause of this Crash, but Thanks anyway Sleepy.

When you have the inirtalise problems Benjamin, is the status led normal?
 

Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
Yes, everything looks normal, but the motors don't sound right. They either throttle too high or I notice the aircraft rotating slightly as I increase the throttle. I instantly stop and turn off the motors, then restart everything. As long as you know there's a problem you can catch it before anything bad happens.
 

Pumpkinguy

Pumpkinguy

Member
If I went all in on a rig that sporadically had these issues i sure as heck wouldn't learn to spot the problem and live with it. I'd dump that fc like a hot potato. Too much money and the health and well being of you and the people around you at stake. Just one guys opinion.
 

Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
It has happened twice on very hot days where it has been flown for many hours.

I have flown 103 hours on this rig and it has earned me £67,000.

How did you come to the conclusion it is the FC Pumpkinguy? Why not the ESCs?

I'm sure your car never develops any issues at all with normal use...;)
 



Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
Careful with paraphrasing. The full sentence is:

I've noticed sometimes my WKM doesn't initialise properly. The motors don't sound quite right on throttle up. Naturally I don't try to take off when it's like this and just unplug and start again. Could be an ESC not initialising also.

You can only replace the part when you know what it is. Since no actual definable fault was detected and the logs show normal operation there is nothing to replace. It could also all be in my mind. Motors not sounding right is quite vague and odd behaviour on the ground could be attributed to a few thing, like the pilot.
 

Hexacrafter

Hexacrafter

Manufacturer
Here is something to try....
Using a great camera on a tripod..... Like a GH4.....
Spool it up several times on camera......Do not try to take off.... just arm... spool up slightly and drop stick..... let motors stop and immediately restart....
Review the footage and slow it down as needed to view all of the props.......
Are they all starting at the same time and at the same speed??
I have seen a lot of slowly dying ESC act weird and start great one time any lazy the next.....
If you identify any lazy motors.....
Examine closer..... try plugging the lazy motor into a different ESC.....ETC to determine whether it is a motor or ESC....
Just a shot in the dark, but high quality camera footage is sometimes the best way to analyze & determine the problem....
Hope this will help...
 

dazzab

dazzab

Member
Sounds like the copter has had a lot of use. What type of motors are on it and have you checked or changed the bearings?
 


Mediakopter.no

Mediakopter.no

Member
It has about 4 hours in the air. Yeti esc, and Tiger MN3515 motors. The bearings seems fine. Motors run smooth, and there is no play.

Received new propellers today, so as soon as the rain stops, I'll start testing, and try to figure out what went wrong. The bad initialise theory sounds like it might be the answer, but I have to be sure.
 

Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
Cool. Sounds like you're on top of it.

There's so many components that have their own little initialization routine something is bound to occasionally be out of sync.

If you own a Windows PC how many times has it randomly failed to start over the years? Just restart and try again. If your car doesn't start first time, try again! Such is life. :)
 


Mediakopter.no

Mediakopter.no

Member
Sounds strange, but I will check it out. Sadly I do not own a Windows pc, so I am not able to view the flight log. I'm leaving for a 4 day canoe trip with my boss-at-home tomorrow morning, but will try to figure this out when I come home again.

Thanks for the tip. This is why I love this forum :)
 


htotheunit

htotheunit

Member
I have had a similar near miss, investigated it and this is what I came up with.

If you hold the sticks to the center position to arm the motors BEFORE the remote has fully switched on (as in you rush switch it on and rush to arm and get in the air.), it can cause issues.

What I found is that mine would spin as though I was holding the yaw fully to the right. I managed to replicate the problem on the bench several times by holding the sticks whilst the start up tone on my Futaba was still going.

As you described my motors sounded as though half my motors powered up quicker than the others. Do you hold your sticks in the bottom center or bottom outside?
 

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