Complete Failure of INSPIRE 1 during flight - Dropped from 400 feet

[Kilrah]

I don't know what you're on, but it seems to be quite good...

 

[The Editor]

Guys, we just do not know yet exactly what caused this and maybe we never will.
When DJI examine the flight logs maybe they will be able to determine what happened and maybe they won't - time will tell.
There are far too many variables in here we do not know:

How old was the battery?
What was the ambient temp?
How many charge/discharge cycles on the pack?
Was it fully charged at take-off?
Had it been sitting and gone into self discharge?
Was there a faulty cell in the pack shown up by full throttle for over 30 seconds?
Had the aircraft previously been in any kind of crash or any situation where one or more motors stalled thus increasing the current through the FET's?
Did the OP always check his motor temps upon landing?

I could carry on typing question but my fingers are sore - the fact is at this juncture we just do not know.

My best guess at this stage is still esc failure and the OP has now confirmed that when he powers up the aircraft he gets an esc failure message.

Let's wait and see what DJI come back with.

 

[ringolong]

From 39 to 40 seconds it appears as if the prop is swinging correctly.

Shouldn't there be a better quality video than what was posted?

 

[SanCap]

This is what it looked like when I did a CSC in flight due to an uncommanded full power take off (phantom 1). I almost got it restarted towards the end of the flight

Crash

 

[Redtazdog]

This is what it looked like when I did a CSC in flight due to an uncommanded full power take off (phantom 1). I almost got it restarted towards the end of the flight

Crash

Now that was some funny chit
It looks like if you were about 30 ft higher you may have had enough time to get it back under control.

 

[jhardway]

From 39 to 40 seconds it appears as if the prop is swinging correctly.

Shouldn't there be a better quality video than what was posted?

From 39 to 40 seconds motor number 3's prop has just entered into a autorotation and just started spinning in the reverse direction. That motor is suppose to rotatate counter clockwise to produce lift. When it first appears in the video the prop is spinning slow in a clockwise direction. As the video continues you sill see it accelerate as the airflow increase up though the rotor system and the inspire is now falling to the ground at a good speed

Also in the video initially the copter spins pretty aggressively as the camera is pointed to the ground but as it tilts up and we could see the copter enter into a stable falling state, it actually only it yawed just over 720 degrees before cutting out. This is probably because of the Inspires anhedral design.

 

[The Editor]

Good grief - This thread is still going with theories upon theories - At the moment we can postulate until the mooing animals make their way back to their barn but we are all just guessing.

I would say the solar flare that occurred on December the 1st had a lot to do with it and whether the OP was wearing any clothing that built up a static charge!

 

[John Casey]

Just wondering why the battery was at 60% if you just took off and flew vertically straight up to 400 ft.? Did you take off with a partially used battery? I have been told never to do that and the result can be that the battery can drop to zero and the aircraft can literally fall out of the sky. Now I'm not sure if that is true but I was just wondering if you are flying straight up from where you are standing, did you take off with a partially used battery inserted? Just a thought...

 

[The Editor]

Just wondering why the battery was at 60% if you just took off and flew vertically straight up to 400 ft.? Did you take off with a partially used battery? I have been told never to do that and the result can be that the battery can drop to zero and the aircraft can literally fall out of the sky. Now I'm not sure if that is true but I was just wondering if you are flying straight up from where you are standing, did you take off with a partially used battery inserted? Just a thought...

Not any more with the latest firmware - Mind you, the OP wasn't running that at the time as it was not public release.

 

[jhardway]

Editor, to me this is a big deal, I am a 333 holder and I use an inspire as my primary device, but to see this happened with out an explanation is very concerning. As a business person, when seeing an event like this, its part of my responsibility to tune in to these matters.

Not only do they inform me on things that may be happening but it also allows me the ability to make better decisions for me, my clients, and the public.

If this happened to me over a collage campus, solar field, other areas I do business with. Then I could be looking at some major liability issues. I work very hard on being safe and creating safe environments.

To see this happen without an answer put up a flag. If we can get decent idea of what may of happened then it help us be safer down the road, and helps the public trust the equipment we use.

So I know some of my post are fairly long in this thread, but if that gets me to an place where it helps me have a better understanding and make better flying decisions, then I am all for seeing what floats here.

So to make a post about how ridiculous (long) this thread has become, for some of us its not. As long as the thread has not become bitter, disrespectful, or way off base and talking about something that is not drone related (maybe like this response). For me then it's not a waste to look over.

It's important to understand what happened here and we may never know, however At the end of the day if learn something new from this thread then it will help make me a better person.

With that said also once this thread has gone far enough for me then then I will simply stop investing my time into it and I feel that is the same for many of the people on here.

I hope you understand, I respect your efforts, your inputs, and answers I find them very helpful from my knowledge, and I think a good amount of the members on this site feel the same way.

I know theories could be way off base but even though they may not be of substance sometime some of those thoughts turn into positive information.

best

 

[The Editor]

Editor, to me this is a big deal, I am a 333 holder and I use an inspire as my primary device, but to see this happened with out an explanation is very concerning. As a business person, when seeing an event like this, its part of my responsibility to tune in to these matters.

Not only do they inform me on things that may be happening but it also allows me the ability to make better decisions for me, my clients, and the public.

If this happened to me over a collage campus, solar field, other areas I do business with. Then I could be looking at some major liability issues. I work very hard on being safe and creating safe environments.

To see this happen without an answer put up a flag. If we can get decent idea of what may of happened then it help us be safer down the road, and helps the public trust the equipment we use.

So I know some of my post are fairly long in this thread, but if that gets me to an place where it helps me have a better understanding and make better flying decisions, then I am all for seeing what floats here.

So to make a post about how ridiculous (long) this thread has become, for some of us its not. As long as the thread has not become bitter, disrespectful, or way off base and talking about something that is not drone related (maybe like this response). For me then it's not a waste to look over.

It's important to understand what happened here and we may never know, however At the end of the day if learn something new from this thread then it will help make me a better person.

With that said also once this thread has gone far enough for me then then I will simply stop investing my time into it and I feel that is the same for many of the people on here.

I hope you understand, I respect your efforts, your inputs, and answers I find them very helpful from my knowledge, and I think a good amount of the members on this site feel the same way.

I know theories could be way off base but even though they may not be of substance sometime some of those thoughts turn into positive information.

best

Understood.

You have probably gathered from my past posts that I also operate commercially and use the Inspire as a tool of work. Safety is my number one priority followed by safety as number two with safety coming up the rear in third place, so I totally understand your sentiments. However, we shouldn't all now start worrying that our Inspires are going to start falling out of the sky since this is an isolated case and not a trend. If that was the case with over 13,500 members as well as the community over on the DJI Forum we would be hearing about it.

Like I mentioned in my earlier post (#89) there are just too many unknowns at the moment for a forensic analysis of what caused this incident. Everything thus far is pure speculation.

The facts we do know:

1. There is at least 34 seconds of fast climb out (possibly full throttle) which asks an awful lot from the batteries cells - Never a good idea
2. We know that the battery was not at 100% at the start of the flight - Again this is bad (although fixed in the most recent FW)
3. We know that the battery had been charged a few days previously - Again, bad since self discharge could have started
4. We now know that an esc error is evident when powering on the aircraft
5. The battery was approximately 5 months old

The Facts we do NOT know:

1. How many charge/discharge cycles were on this pack - This has a direct bearing on how the pack will perform and also there would be an increase in internal resistance of the cells, thus they would not deliver power so readily under high demand
2. Had the pack been correctly calibrated at the required intervals - Important because without this the software has no accurate gauge of what is '100%' and what is '0%'. The battery firmware also takes into account aging so if calibration had not been done correctly the firmware would not be calculating remaining flight times or fuel levels accurately.
3. Had the aircraft been in ANY sort of crash prior to this event - Important since at some point the motor(s) may have stalled on something causing a surge of current (even momentarily) through the FET's on the esc's
4. What was the ambient temperature - This obviously has a direct bearing on how well the pack performs (or not)!
5. We do not know how many days the OP had self discharge set for on that particular battery

We may never know what actually happened on this one since it appears the Flight Logs stopped recording and therefore DJI may not be able to determine the cause. What I think we can say though is it does not appear to be a trend and we shouldn't all now consider grounding our fleet.

 

[ringolong]

From 39 to 40 seconds motor number 3's prop has just entered into a autorotation and just started spinning in the reverse direction. That motor is suppose to rotatate counter clockwise to produce lift. When it first appears in the video the prop is spinning slow in a clockwise direction. As the video continues you sill see it accelerate as the airflow increase up though the rotor system and the inspire is now falling to the ground at a good speed

Also in the video initially the copter spins pretty aggressively as the camera is pointed to the ground but as it tilts up and we could see the copter enter into a stable falling state, it actually only it yawed just over 720 degrees before cutting out. This is probably because of the Inspires anhedral design.

Yep, you are correct. I had to slow it down to really see which way it was spinning.

 

[xahhax]

I feel sorry for the pilot here. When I see comments 'it can only be a pilot error' certainly makes me think that a lot of drones pilot have little to none RC flying experience.
If you had over thousands of RC flights (fixed wings, helis, multis etc) you would know ESC do fail, that electronic components (being servos, flybarless controllers, RX/TX etc) do fail and end up being the source of most crashes for experienced pilots. None of the electronics in those devices (including DJI here) are military grade or have embedded redundancy. The firmware release QA process wouldn't pass the laugh test in tech companies working for real time systems (e.g. transportation, military, medical...)
Of course we all do expect a 3K or 5K equipment not to fail. But they do. It's not ALL pilot error....

The best and most honest description & disclaimer of this I ever read was in a diver computer manual. If you don't dive, think about this: if you rely solely on your computer in a tech dive and it fails, well, goodbye...:

This computer has bugs. Although we haven’t found them all yet, they are there. It is
certain that there are things that this computer does that either we didn’t think about,

or planned for it to do something different. Never risk your life on only one source of

information. Use a second computer or tables. If you choose to make riskier dives,

obtain the proper training and work up to them slowly to gain experience.


This computer will fail. It is not whether it will fail but when it will fail. Do not depend on

it. Always have a plan on how to handle failures. Automatic systems are no substitute

for knowledge and training.

 

[Kilrah]

Exactly.
The #1 problem is that we're in a paradoxal situation here, where on one side people tout aviation-level reliability and safety measures (including licences etc) but on the other side with technology that is decades away from reaching the actual level they're promoting, and they kinda know it...but don't accept it because it would obviously compromise their thought process and the whole industry they want to be part of and have started making money on.

If people who go all over the place about "drone" safety actually honestly followed their own principle they would not be selling any, and wouldn't want any in the air for purposes other than necessary testing to improve the platforms, because none of the existing offers is anywhere near an "acceptable" reliability level... and, to piggyback on your diver computer manual's excellent advice - there are NO proper ways to handle any failures and NO "second sources" to rely on.

What they won't accept either is that should they really want to go where they say they want they'd likely be put out of the game, because that $3-5k machine they find expensive is absolute peanuts compared to what would be needed to offer satisfactory safety levels. The day we get a "safe" machine it will be 100x more expensive.