I was on a survey job for the Sacramento Kings new arena and I discovered a few good tips.

• Set your RTL at %30 of battery drain.
• Carry good electrical tape

• Buy a backup Iris+

• Get a lens guard for your GoPro.

I decided to allow my unit drain to 20% and RTL. I was 60m up and only around 100m away. The Droid lady said "Low battery, returning to launch" Sounds good to me. As it's decending I notice I'm well off the mark and headed into oncoming traffic. It's a tight quarters job and you gotta be ready. I begin to nudge it over the K rail and I hear the motors begin to decelerate. I hit hard left and, well watch the quick video.

The gimbal plate cracked in half but I was able to use electrical tape to finish the job. I had a Mobius on there for shits and giggles and the GoPro was the survey unit. You'll see it fly. Gotta hand it to GoPro. That's one tough unit. I did have a CPL filter on there, but if you can use a cheap 3D printed hood, do it. That filter saved my lens.

So if you're ever unsure out there. Trust your gut and RTL.


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Actually not to bad, at least from the point of view that you did manage to keep it for landing in the street and flew it to within a few feet of where you were standing.

I am worried as to why it appears to impact twice, once at about 5 seconds into the video and again at 9 seconds with another 2-3 seconds before you hear the motor disengage beep and the props stop. I'm going to guess that as it impacted the first time, you pulled the throttle all the way down and left, to disengage? If so, why did it keep flying and flopping around trying to completely destroy itself for another 7-8 seconds before you could get the motors to stop turning?

It still had 22% battery when I metered it. It was in AUTO mode and was RTL via Mission Planner. I'm am not sure if flipping out of AUTO would have changed results or flipping the RTL switch (or Loiter) was the right thing then attempting to fly manual etc... I was letting run it's course then just correcting in AUTO on the landing. Lots of variables and everything happens pretty fast. I had the stick LEFT DOWN at the point of impact. The Tarot plate cracked in half and my 3D printed GoPro holder broke. A little eletrical tape and I was up again. Finished the day with it. A few tweaks of programming and I'll be good. Can you make a KILL SWITCH on one of the channels?

My question exactly. In a somewhat similar incident, I was flying from a ball park, enabled RTL (for fun) and as fate would have it, It wanted to land on top of my OSD set on a tripod about 10 feet from the takeoff point. Rather than move the tripod I maneuvered the Iris over a few feet. Upon 'landing' it continued to try to move in the direction of where it had wanted to land. Stick down and left as I watched it slowly lean towards me, literally rolling all the way over onto its back ,in slow motion. No damage to the Iris+, but all 4 props destroyed as I stand there, helpless, throttle down and left and the props continue to spin. from touch down, through a slow rollover and for 2-3 seconds upside down, before the thing finally disengaged the motors. Thankfully I was in a grass field and not on asphalt. Still, the point is, is a KILL SWITCH programmable?

I did an extensive calibration in MP. Turn auto lock off and keep spinning drone until you have a complete sphere. It has worked wonders for stability and control. 

It amazes me how people rely on a last-resort safety feature to bring the expensive machine home. Stupid stupid.

It's like me relying on the anti-crash feature on my car to hit the brakes when the car in front of me stops. 

Turn off the battery fail-safe, fly with a bit of concentration, know your situation and stop ruining it for the rest of us.

Listen up Chuck Yeager, Testing failsafe measures is part of the process. I'm sure you can fly circles around me blah, blah, blah... If you're not going to be part of the conversation then what's your point? This is helpful information for those of us not as skilled as yourself. I dumped my drone, not yours. 

Maybe he was referring to me as well. I must admit though, I think I'll pass on the advice to turn off the battery failsafe on my quad, or the anti-crash feature on my car. Guess you can just call me Stupid! :)

As a relative novice, particularly to pixhawk/3dr, I do find this helpful.   Extremely helpful.  Crispin is the first person I've come across to suggest that flying with battery failsafe active is "stupid stupid."  Assuming he is correct, I'd like to know what his rationale is.  There is definitely a difference between stupidity and inexperience.

Having said that, I must admit that the more I've flown, I've actually found it to  safer without the failsafes on.  Instead I concentrate very closely on the ground station app and the Iris+ itself (as Crispin seems to suggest).  I fly in pretty remote areas without people around, so I can afford to experiment a little.

My issue with the failsafes (both battery and GPS) is that they can take control of the Iris at inopportune moments.  For example, in general I like to land with 50% or more battery remaining, but on a few occasions I've had to push it below 30% because I got myself into situations where I had to go for a back up landing site.  One time there were much higher winds than expected and so the Iris had to work so hard to execute the mission - it was an effort to abort and get it to a safe landing zone.  I think I ran that battery down to 25% that time.  Another time I had a ski break and I couldn't get there in time.  And another time a moose showed up unexpectedly and I just didn't want to land anywhere near him so I had to go for a back up.

Anyway, I'm definitely NOT suggesting that anyone else disables the failsafes.  I'm just not experienced enough to really make that call.  I would be super interested to hear what other people recommend and WHY.

The point is: I bought an Autonomous Flying Robot so it WOULD do the things I tell it to do. I am depending on it to act as I tell it to. As far as safety is concerned, I had permission to fly and everyone was aware of the drone. No one was ever in any danger. It was an planned aerial survey. I chose to let it run to the point and come home. Now I have surmised that it does not take consideration in for height or distance from the controller; it's just low on gas. I find that information useful. I am using this drone as a tool to collect information and footage. Clean information and footage. That requires GPS flight plans. I am sure there are many out there who can fly better than I can, but I get around just fine. I know where my sweet spot is in air time and can plan missions accordingly. Is trying to get the most out of my battery a sin? Oh well... 

My point is that you were unaware of what was going on. a) you had your battery failsafe set high (ok, that could be "on purpose"). b) you let your quad fly until it kicked in. At that point your batteries did not have enough guts to get you home and it ditched. 

The battery fail-safe cannot accurately know or predict what the batteries are up to. It can only measure the voltage and country the mAh used. It has no idea when it is going to fall off a cliff. I have lipos which are old and appear full. The voltage falls in such a way that the failsafe would not be able to get it home. The mAh used is nowhere near what I set it in MP.

As for getting the most out of your battery - it actually is bad (sin? no, that's your call :) )

A lipo should not be over-discharged. Anything below 3.3-3.4v/cell is about done in my books (opinions vary). Anything more than that and you're starting to damage the lipo and for what purpose? Getting an extra two minutes out of a flight? If you had a headwind trying to come back you're toast.

It's a bummer you crashed - it's good you posted about it (hopefully it'll make others thing a bit too). It's the good and the bad posts which move the safety forward :)

Erik - 

My point is that relying on something like battery fail-safe and using that as a "I don't have to worry about the battery" is not wise. Having it as a last resort - I'll buy that.

Jimmy's quote "I decided to allow my unit drain to 20% and RTL." is stating just that. Does RTL not first climb 10 or 20 meters? Not sure on the battery fail-safe. If it is the same as normal RTL then that is hammering an already low battery.

You should have either some form of telemetry reporting your battery voltage or a timer telling you when you have flown x minutes and then land. Eeking out every last drop out of a battery is pointless unless you don't care about the battery.

Sorry to sound offended but I pride myself on safety. I was regretting not returning at 30% I have to fly that spot 24+ more times this year. I'll split the job site in half and be fine at 50 to 60% Another company is stitching the photos so I was hoping to give concurrent data in one pass with the overlap they requested. I am running a SX260 next week so GPS data will be included. (which is also scaring the crap out of me) 

It was a test. It failed I get it. I metered the battery after and it said 22% 

With all that being said what would you recommend for maximum MAh for a 5100? 


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