I just lost my second quad

Nerox · Post by **Nerox** » Mon Aug 04, 2014 9:52 pm

Hello,

this is not meant to be an insulting post to anybody.

The first quad I lost was mostly due to my error. I had it running with a throttle-cutoff-failsafe setting on my very old 35 Mhz system. One thing lead to another,there was a brief interference and it basically fell from the sky into a 2 meter high canola field.It was mostly a quick and dirty quad and although it fell into the field approximately 25 meters away from me (I am not kidding) there was no way to recover it. I was raging after I lost it.

The second quad has been a project over the past 2 months. I started building it with winding my own motors - the kit itself, including stators etc. costs 130€ for 4 motors. Carbon frame, FrSky Taranis, 3S 6000 mAh - these were all things I needed to buy (as a college student). I started off with the basics and flew it on 2.4 Ghz. It flew great. then I started to add things. 3DR Radio, Neo 6M version 3 GPS, Q-Brain Speed Controller flashed with BL Heli. I then switched to OpenLRS on 433 Mhz, first 100mW, then 1W to ensure a stable link. I added a beeper and thought with 3DR Telemetry I'll be on the safe side.
Next thing was a 2.4 Ghz video downlink, 500 mW, Sony 600 lines Super HAD camera. But I was a cautious person and my personal height limit was 300 meters - I never went above it. I also had the fence radius set to the default 600 meters, why the heck should I go further? I just wanted some nice FPVing, thats all.

Fail safe was calibrated and worked like a charm, as you might have read in a previous thread from me.

Today this happend: Coper was pretty far away, but I hadn't hit the fence, so lets say, 500 meters. Height was BELOW 50 meters, as I climbed to approximately 40 meters in the beginning and then set Baro on - this is what I do usually to prevent the copter from climbing too high or crashing.
When I decided I flew enough, I just switched to return to home. I saw the copter turning as usual on the (still great) video link and from one second to another, before the copter finished turning to face the home point, all motors stopped, the copter did some turns and after two seconds I lost the video link as it came too far to the ground. It basically fell from the sky like a rock - again.

If I saw it correctly, the quad fell into a 500x500 meter field of rye. If anybody knows the feeling of searching and RC vehicle in rye, you know that its impossible to locate. I regained videolink for another 30 minutes, just seeing some rye and green gras in the lens. After that, the additional 3S 350mAh battery for Video TX/Camera ran out of power.
There was no chance to activate the beeper or regain link with the 3DR radio to check the GPS position, so I assume that due to the fall the main flight pack (3S 6000 mAh) disconnected itself from the 4mm gold plugs. Another bummer is that the last saved GPS position on the 3DR radio can't be true in any way and I suppose it got out of range before it crashed. I've been able to go to 300 meter with the 3DR radio but not further.

Even if I find the quad again tomorrow by using a big 1.6 meter wingspan plane with a full hd camera mounted at the bottom I will most likely sell all my MultiWii staff. If it works, its a great thing. But until today I never had a 100% feeling of being able to rely on the electronics used (and I am aware of proper wiring, using heat shrinks and all the stuff you need to pay attention to). I even used a 1W transmitter to eliminate all sources of errors regarding the RC System - and I still had
video link when the thing crashed. So the probability that I lost connection to my OpenLRS is close to 0 and even then it should have gone to fail safe mode, thus returning to home.
I NEVER had those problems flying with an RC plane.

My point here is that everybody should expect crashes at any time and if you ever start flying your MultiWii or any other RC vehicle you should already have said "good bye!" to it in your mind. If you don't do that and always think about what could happen financially (not speaking of somebody gets hit by a 1.5kg Quadcopter that falls off the sky - this actually proves my point of taking precautions like height limits and NEVER EVER flying close to residential areas or streets. Never!), you're gonna have a bad time. DJI has its fly aways and for me MultiWii has its "yeah I just decide to quit working and there is nothing you can do about it", at least for me (NOT saying this is a common thing and its actually better than a fly away). Even double- or triple-safe-systems fail.
Coming back to the point of selling, all this has caused me so much trouble in the recent days. I could think of what went wrong this time for hours and come up with possibilities over possibilities, but I doubt that I would find any solution that would enable me to go flying again with a quadcopter and say "yes, this thing is actually safe". It is supposed to be a hobby that is fun. When I crashed my foamies, it was always 100% my error, sometimes I didn't glue things perfectly or sometimes I flew into a tree. After that I was like, whatever, its my fault anyway.
Every time I started my copter I was like "is it going to fly away today?"? It was more like a constant feeling of fear, stress and tension if everything will work properly. For some reason, flying quad has put me in a mood where I started to use my whole semester break to "improve" the quadcopter up to a point where I thought it was improved up to 150% - and then it fell from the sky.

I now also get why customized Drones and other professional stuff is so expensive.

I had fun too, yes. And I think there are many great ways of having fun with this machinery. But everybody should bear in mind that if you decide to go for an ambitious project like this, it could go bust from 1 second to another - its Do-It-Yourself and NOT preassembled and ready to compensate all your mistakes-material.

Just thought I'd share. (for some reason I'm completly calm although its 11pm and somewhere in the rye there is a 800 dollar machine lying around).

Thanks for reading.

Nerox · Post by **Nerox** » Tue Aug 05, 2014 12:45 pm

As expected, I wasn't able to recover the quad. I have around 40 minutes of Full HD video flying over the field, but there seems to be no clue. I wouldn't even know where to start. Its starting to rain so most of the electronics is defective now anyway. The cornfield will be harvested on friday and I already contacted the farmer. He might find some leftovers, but even if, most of the stuff will be unusable and I will most likely throw it in the garbage can as it would be unfair to get it working again and then sell it to a trusting person.
Btw: This could be my thread and video. Looks exactly the same as my crash.
http://www.rcgroups.com/forums/showthread.php?t=1546341

This is it for the MultiWii thing then at least for me. If you start and you see videos like Team Blacksheep, you think wooooooow, I can do that. And then you start running into a direction where your mind only focuses on getting videos like them. There are enough idiots out there to actually believe the shit those people are talking (like, we do not break the law, we are operating in a grey area), and I am obviously 100% one of them.

I will go back to fly a foamie in my range of sight (which is 300 meters at absolut maximum) every now and then. It might crash as well. I might even loose it in a corn field, who knows. But at least then I didn't feel like a total retard at the end of the day trying to achieve something that can never be done. The internet is full of crap, and I will finish this post with one of the best examples to explain why the direction I've been heading into is completly the wrong one. Maybe one or a few beginners will bear that in mind when building their first quad.

This time its DJI:
https://www.youtube.com/watch?v=GfxdeRx2fLA

waltr · Post by **waltr** » Tue Aug 05, 2014 3:54 pm

Am sorry to hear that you couldn't find your copter.
Do consider either a Lost Model buzzer which you activate from an AUX channel and something like the Loc8tor.
http://www.hobbyking.com/hobbyking/stor ... zzer_.html
http://www.loc8tor.com/everyday/loc8tor-lite-rc.html/
These can also be very useful on a small foamie.

As a kid my brothers and I lost a number of models in the corn fields so I know what its like looking. Today, after many years of flying RC aircraft I would not fly a multi-rotor over a corn field and get very nervous if I fly over trees. Not sure which is worse, seeing the model in a tree but too far up to get or not finding it in the corn.
Just hope your quad doesn't damage the farmer's harvester.

As for MultiWii being the cause, well there is lots of things to go wrong on a copter so always expect a failure. I've never have a failure that could be attributed to MW.
On my quads I 'Keep It Simple' which has a lot less things to go wrong.
And yes, DJI fly a ways are very well known about as are with other copter that relies on GPS instead of pilot skill.

As for electronic getting wet: this typically does not hurt the boards if they are powered off. The battery should have died so bd should not be powered.
If you find the lost quads then wash the boards with mild soap and warm water, rinse well, blow off with compressed air, re-rinse with distilled water, blow dry then finally bake in an oven at not more than 125°F for an hour or put into a sealed bag (zip lock) with some rice over night to absorb the remaining moisture. Power up the board with the USB and see if it works.

PatrikE · Post by **PatrikE** » Tue Aug 05, 2014 6:42 pm

The only time a MultiWii have fallen from the sky for me was because of it Browned out...
Besides from user faults.

The plane was loaded with.
FrSky rx.
Mega2560 FC With FixedWing RTH code
Gps.
3Dr radio.
4 servos for flight control.
Simple Pan servo for FPV camera.
5v Fpv camera.
200mw 5.8G VTX.

Unknown size of BEC i the ESC.
I guess 2A

Result was FC rebooted in air..
The plane went in a spiral down in a tree.
I did it twice before i realized what really happened.

Mega boards is sensitive to voltage drops.
It's normal to add a large capacitor to help a little.
A separate bec for FC plus a BEC for the rest of the equipment will prevent Brownout.

Nerox · Post by **Nerox** » Tue Aug 05, 2014 7:13 pm

Hi,
both the board and RX were quipped with this: (yes, there were two of those on board)
http://hobbyking.com/hobbyking/store/__ ... ector.html

Both the board and the RX were powered by an external 5V 5A switching BEC. The BEC of the ESC was deactivated.

This is what I meant with, that thing was constructed idiot-proof.

brewski · Post by **brewski** » Tue Aug 05, 2014 8:45 pm

Which make/model Mega2560? I have a Crius AIOP V2 which has a shottky diode in series with 5V input & this introduces between .4-.5 V voltage drop depending on current. The Atmega2560 min operating voltage @ 16Mhz is 4.5V, so it is running dangerously close with 5V input. There are two solutions-
1. Bridge out the diode
2. Use external BEC with 5.5V output (or select 6V on BEC & add another shottky diode in 6V line).

ArrogantDuck · Post by **ArrogantDuck** » Wed Aug 06, 2014 2:49 pm

Yours is the emotional expression of pain we all feel on the first, second and third lost quad.

I feel you.

As you go forth be careful of putting your absolute in any of this stuff, as it appears you did on multiwii being perfect. I think any fc could have problems; amazingly, yesterday I got to see the exploding-prop moment right before a plummet from about 20m up; things happen with so many variables.

Triple fail safe, in this case on a quad, isn't realistic: if one motor goes, it's a rock in the air.

One of those gps chips might be a great investment for your next craft.

This is such a fun hobby, even with its foibles.

brewski · Post by **brewski** » Fri Aug 08, 2014 5:10 am

Have you seen the rescue chute for multirotors http://www.opale-paramodels.com/index.p ... dji-s800-2
Uses a servo to deploy so can easily be done with MW. Wouldn't be too hard to make one either as the chutes are available from the guys that sell stuff for model rocketry.

scrat · Post by **scrat** » Tue Aug 12, 2014 12:08 pm

Nerox wrote:Hi,
both the board and RX were quipped with this: (yes, there were two of those on board)
http://hobbyking.com/hobbyking/store/__ ... ector.html

Both the board and the RX were powered by an external 5V 5A switching BEC. The BEC of the ESC was deactivated.

This is what I meant with, that thing was constructed idiot-proof.

You didn't answer...what FC did you have?

Nerox · Post by **Nerox** » Wed Aug 13, 2014 6:48 pm

scrat wrote:
Nerox wrote:Hi,
both the board and RX were quipped with this: (yes, there were two of those on board)
http://hobbyking.com/hobbyking/store/__ ... ector.html

Both the board and the RX were powered by an external 5V 5A switching BEC. The BEC of the ESC was deactivated.

This is what I meant with, that thing was constructed idiot-proof.

You didn't answer...what FC did you have?

Hi,

sorry.

First, I was able to recover the quad after I spent 5 hours harvesting rye with the farmer. Quite interesting.
Nothing much was broken, the only thing that took damage and needs to go into the garbage can is the 3S 5800 mAh Turnigy battery, as one cell is open. Gonna re-use the 2 intact cells, so the damage is 40$ for sthe battery respectively 12$ for the damaged cell. Ah, and one propeller.
A friend of mine opened a Dropbox folder:
https://www.dropbox.com/sh/g2djvz7aghv7 ... r7vr2B2Yja

So, I haven't been able to reproduce why the copter crashed. The battery was disconnected from the copter due to the crash (lying next to it on he fiels), thats why I wasn't able to read the GPS values via 3DR Radio, as the 3DR was powered with the main flight pack.

As I am also using the CRIUS AIOP V.2 and I wasn't aware of the voltage drop. My BEC can either deliver 5V or 6V so would there any reason not to set the BEC to 6V in the first place and thus powering the bord with ~5.5 Volts? Or would the ~.5 Volts more kill the Crius?

So there are some things that could have caused the crash:
-The main battery disconnected during the flight. As the Video TX and camera used an additional battery, I was still be able to have video link. I can't tell if that happend or not, but it seems possible.
-The board rebooted, maybe due to the 4.5 Volt voltage issues.
-The board rebooted for some other reason

The copter already flew&crashed again, but this time due to wind conditions (DON'T fly your copter when wind speed is ~35 knots). You will maybe be able to fly against the wind, but if you turn to fly back, it will speed into the ground

However, everything is still working properly besides the Barometer (showing fluctuating height values ~10m). But maybe that was also due to the wind conditions.

The farmer got a crate of beer from me, really nice people.

Greetings from Germany.

brewski · Post by **brewski** » Wed Aug 13, 2014 9:09 pm

At least you got it back with most parts reusable. Re the voltage. Atmega 2560 is rated 4.5 to 5.5V @ 16Mhz, If you use 6V on UBec you would need to install a diode in series with 6V input. The other solution is to use 5V setting on UBec & short out the diode on FC. The diode is in lower RHS to right of the protection fuse which has gold coloured end caps. You need to be good at soldering & have a fine tip soldering iron as diode is surface mount.

fuh · Post by **fuh** » Thu Aug 14, 2014 2:42 am

To see if I get it right, you're blaming Multiwii for what you suppose could have been a bullet connector getting loose ?

Nerox · Post by **Nerox** » Thu Aug 14, 2014 5:22 pm

Nope. You didn't get it right.

Nerox wrote:this is not meant to be an insulting post to anybody.

The reason for posting this:

Nerox wrote:I had fun too, yes. And I think there are many great ways of having fun with this machinery. But everybody should bear in mind that if you decide to go for an ambitious project like this, it could go bust from 1 second to another - its Do-It-Yourself and NOT preassembled and ready to compensate all your mistakes-material.

Just thought I'd share.

At no point I put 100% blame on MultiWii, if yes, show it to me. I just wanted to share my experience and got some nice words from people like ArrogantDuck.
Its just sometimes frustrating if the same thing happend twice, in the same way.

I can't reproduce the way this happend, I doubt that the bullet connector got loose (I really really doubt it!), but its one of the few explanations that could explain how it happend.

fuh · Post by **fuh** » Thu Aug 14, 2014 6:32 pm

Maybe it's the internet but the general tone of your post put that idea on the back of my mind. ;-)

Actually it's more simple to explain that you thought: if you're within range of the telemetry link, if the telemetry is connected to the main power, if the last GPS coords were invalid on ground station, if VTX is powered by a different battery and was the only thing working.. guess what ?

1) Main battery went dead with low voltage.

OR

2) Main power line went dead with a connection failure somewhere.

ArrogantDuck · Post by **ArrogantDuck** » Sun Aug 17, 2014 10:56 pm

Glad you got your craft back!

I have one I recently crapped. Sure is kinda cool piloting a previously crashed copter: qav-style that was squashed on a crash. Everything intact...

I share that cuz that's all I got!
Enjoy!

(Three exclamation post. Cool.)

e_lm_70 · Post by **e_lm_70** » Mon Aug 18, 2014 2:50 pm

There are tons of possible reason why a copter will decided to crash down in any moment.

4 motor, 4 prop 4 esc , tons of connections .. tons of single point of failure in a "complex" system.

Still ... the least possible reason is due to a bug in the multiwii firmware.

MultiWii is simple, and being simple has less possibility to have a bug inside

I also recently got a crash without reason from my MultiWii 2.2 Tricopter .. while playing with the gimbal controller, that is connected from TX-RX via MultiWii 2.2 control board (since I use PPM RX) ... out of blue it decided to switch off all 3 motor and make a 180 roll ... and crash down.. but most possibly I got a failure on the ESC to Control Board connection ... or the battery got unplug ... (gimbal was controlled over the balance port of the battery .. this was working all the time)

Here is the lucky video ... instead of fail me over the lake or when I was almost 100m up in the air ... it fail on me when I was only 1m above the ground ...

http://www.youtube.com/watch?v=N02fpcjH7JI

Copter have been fixed ... it works even better then before .. but I need to test it more .. since I don't want to crash it again

nechaus · Post by **nechaus** » Sat Oct 11, 2014 2:16 pm

There is a bug in the navi b7 beta with the baro not turning off..

But man.. you have to expect this to happen..
I feel safe using my mini quads around the suburbs.. and I use my big 450mm + when @ fields, I use extremely over powered machines that break frames, props, bearings, batteries, ego..

Its all apart of the fun.
The other day I crashed my 3d printed frame that took hours and hours, i mean lots of hours to print into a football post.... oh that was a joy moment..

I still love doing it haha...

And its an expensive hobby.. I have a couple of multiwii boards, AP, NAZA.. ect..
but I love it, I also love flying planes as well.. can be so much cheaper.....

MultiWii