RTH questions

[bonie for my droniecc]

My question is-
if the AC is already on rth low battery, then the RC becomes disconnected, would the AC attempt to retrace it's flight path trying to re-establish connection to the RC even if it's path is opposite of the home point?
Example:
Fly 1000ft away
AC signals rth low battery
AC travels toward home point
AC is 600 ft from home point
AC loses connection to RC
Does the AC now head back toward 1000ft away for 60 secs trying to reconnect or does it continue rth?

 

[BD0G]

Nope! Home Point is recorded at take off. That point is used for reference no matter if the Remote
Controller is connected or not. It will use that point as the one to return to related to all Return to Home operations.

However, if one updates and changes thier Home Point during the flight then of course the Aircraft will use that as the destination to return to. Ex . Launch from a boat - boat moves and pilot updates Home Point to a new location as the boat has now moved to that location and they dont want the aircraft to use precious battery power to return to an area that is now far away from the current position of the boat.

 

[Meta4]

My question is-
if the AC is already on rth low battery, then the RC becomes disconnected, would the AC attempt to retrace it's flight path trying to re-establish connection to the RC even if it's path is opposite of the home point?
...
Does the AC now head back toward 1000ft away for 60 secs trying to reconnect or does it continue rth?

The manual doesn't specify what would happen in that particular situation but it should be fairly easy to test to find out.
Do in a large, open area where there's nothing to hit.

Here's all the manual has to say about Failsafe RTH.
Failsafe RTH
The Forward Vision System allows the aircraft to create a real-time map of its flight route as it flies.
If the Home Point was successfully recorded and the compass is functioning normally, Failsafe RTH automatically activates after the remote control signal is lost for more than two seconds.
When Failsafe RTH is activated, the aircraft starts to retrace its original flight route.
If the remote control signal is re-established within 60 seconds of Failsafe RTH being activated, the aircraft hovers at its present location for 10 seconds and waits for pilot commands.
The user may tap in the DJI GO 4 or press the RTH button on the remote controller to cancel Failsafe RTH and retake control.
If no pilot command is given, the aircraft flies to the Home Point in a straight line.
If the remote control signal is still lost 60 seconds after activating Failsafe RTH, the aircraft stops retracing its original flight route and flies to Home Point in a straight line.

Nope! Home Point is recorded at take off.

You need to read the question again.

 

[bonie for my droniecc]

Thx meta, so I would do a test if I had my m2z.... RC disconnected and never regained during low battery rth. @sar104 has helped w/plotting a search area but I still can't find it.

 

[sar104]

My question is-
if the AC is already on rth low battery, then the RC becomes disconnected, would the AC attempt to retrace it's flight path trying to re-establish connection to the RC even if it's path is opposite of the home point?
Example:
Fly 1000ft away
AC signals rth low battery
AC travels toward home point
AC is 600 ft from home point
AC loses connection to RC
Does the AC now head back toward 1000ft away for 60 secs trying to reconnect or does it continue rth?

It will continue RTH. It makes no sense to switch to failsafe RTH if any other RTH mode is currently running.

 

[bonie for my droniecc]

It will continue RTH. It makes no sense to switch to failsafe RTH if any other RTH mode is currently running.

Thx sar, I'm very thankful for your previous help. Do you think it's plausible that it was only a RC disconnect and tried to make it home but landed short? I'm at a loss- literally [emoji22]

 

[sar104]

Thx sar, I'm very thankful for your previous help. Do you think it's plausible that it was only a RC disconnect and tried to make it home but landed short? I'm at a loss- literally [emoji22]

I see no reason for a disconnect - the signal was solid until the abrupt end of the log. And it had plenty of battery reserve to get home.

 

[Mad Mavic]

Sorry, I may have missed it, but was your drone a Mavic?

You stated that the AC battery was low. The Mavic Pro has a low limit at which it will initiate a landing regardless if its in a RTH. The more important thing for you at this point seems to be getting your hands on the last known GPS coordinates from the Go4 app.

I've used an app on my iphone called "Commander Compass Go" to locate mine on two occasions. Its very accurate. I almost stepped on my drone on the first hunt. The second hunt found it 90 feet up in a tree.

If you can get the last known coordinates, you should be able to find the drone.Also, uploading your flight data to Airdata.com is a good way to get the forensics on what all happened.

Hope that helped

 

[sar104]

Sorry, I may have missed it, but was your drone a Mavic?

You stated that the AC battery was low. The Mavic Pro has a low limit at which it will initiate a landing regardless if its in a RTH. The more important thing for you at this point seems to be getting your hands on the last known GPS coordinates from the Go4 app.

I've used an app on my iphone called "Commander Compass Go" to locate mine on two occasions. Its very accurate. I almost stepped on my drone on the first hunt. The second hunt found it 90 feet up in a tree.

If you can get the last known coordinates, you should be able to find the drone.Also, uploading your flight data to Airdata.com is a good way to get the forensics on what all happened.

Hope that helped

That's not what happened. The aircraft was nowhere near the critical landing battery level - it would have made it home with around 34% battery left:

 

[Mad Mavic]

Drones can do some weird stuff. I once flew up the side of a hill in my area that's about 1000 above my takeoff point. Before making the climb, I burned 40 % power and another 20 on the climb up. At the top my low battery alarm activated. My first thought was I had 10%+ power left before reaching critical mass of 20%, the amount of power it took me to actually make the climb. Therefore I could look around for a minute, but something told me to hit the RTH which I did. When I landed I had 1% power remaining. I was thinking I should have had 10% or more power remaining since I was on a decent. What I discovered is that the Mavic burns a lot of power to slow itself down during decent so as to not exceed 45 MPH.

Anyway, just thought I would share that. I have also Had a dry solder joint detach in mid flight, due obviously to a mistake during manufacturing. .

Looks like getting those coordinates would be handy, hope you find it.

 

[bonie for my droniecc]

Sar, Words do not express my gratitude in your 1. willingness to help & 2. your expertise (I should've reversed the order). There are many that help; but few with your knowledge!!!! Thanks again
To be clear, Thank you to all who have taken the time to read/reply. I appreciate it
The flight log was #13 in a previous thread if anyone is interested, I like the team approach when there is something to be contributed

 

[bonie for my droniecc]

M2Z, always performing as it should until this flight

 

[bonie for my droniecc]

Lost my drone- mavic 2 zoom

DJI Flight Log Viewer - PhantomHelp.com

 

[Mad Mavic]

Thx meta, so I would do a test if I had my m2z.... RC disconnected and never regained during low battery rth. @sar104 has helped w/plotting a search area but I still can't find it.

This is a link to my most recent anomaly involving a similar event in which I completely lost signal and didn't regain signal until I drove to the crash site. In doing so, I feel I was able to collect additional GPS information which revealed the actual crash site was about 100 yards on a RTH vector. As you may notice in the flight data provided HERE, the last Known GPS coordinate is not the same as where the flight path stopped on the Airdata map. I feel driving to the crash site while the drone still had power, was key, but not positive.

Another anomaly in my crash data is the name associated with my drone. The name indicated at the time of crash was not the name of my drone. How it got changed is a complete mystery. My only guess is from a firmware update.

At any rate, assuming it lost power at last GPS coordinate, then someone may be able to calculate the point of impact using the following:

Last Know position: 42.534822N -76.683178W.
mass: 1.7 pounds,
Forward velocity: 27 MPH
Trajectory: approximately 260 degrees (this is assumed that the map view is North-Up)
quartering tail wind: 140 degree (quartering tailwind is assumed based on North-Up)
Wind speed:.6 mph

Its a long shot since the lights went out at almost 1300 feet AGL., but I'm guessing its in the trees just below the last known position. Why the lights went out is a mystery without video from the drone.

Assuming it is in the tree, I just went through that in the crash listed above, and I have to say, a Mavic blends in very well with the Fall leaves; making it all but impossible to locate. It ended up 90 feet up in a tree I wasn't about to climb. So I simply went to walmart, bought a slingshot, some 20 pound test line, and large fishing weights with a wire eyelet to fasten the fishing line. After several hours searching, I finally located the drone hanging like a bat. It took about twenty shots with the slingshot before I was able to cast it over the right branch. After some vigorous shaking it came tumbling down and is flying today. I do wish I had staged my two teenagers at the bottom with a blanket to catch it, but it was "too cold out" LOL

hope something in this helps

 

[sar104]

This is a link to my most recent anomaly involving a similar event in which I completely lost signal and didn't regain signal until I drove to the crash site. In doing so, I feel I was able to collect additional GPS information which revealed the actual crash site was about 100 yards on a RTH vector. As you may notice in the flight data provided HERE, the last Known GPS coordinate is not the same as where the flight path stopped on the Airdata map. I feel driving to the crash site while the drone still had power, was key, but not positive.

Another anomaly in my crash data is the name associated with my drone. The name indicated at the time of crash was not the name of my drone. How it got changed is a complete mystery. My only guess is from a firmware update.

At any rate, assuming it lost power at last GPS coordinate, then someone may be able to calculate the point of impact using the following:

Last Know position: 42.534822N -76.683178W.
mass: 1.7 pounds,
Forward velocity: 27 MPH
Trajectory: approximately 260 degrees (this is assumed that the map view is North-Up)
quartering tail wind: 140 degree (quartering tailwind is assumed based on North-Up)
Wind speed:.6 mph

Its a long shot since the lights went out at almost 1300 feet AGL., but I'm guessing its in the trees just below the last known position. Why the lights went out is a mystery without video from the drone.

Assuming it is in the tree, I just went through that in the crash listed above, and I have to say, a Mavic blends in very well with the Fall leaves; making it all but impossible to locate. It ended up 90 feet up in a tree I wasn't about to climb. So I simply went to walmart, bought a slingshot, some 20 pound test line, and large fishing weights with a wire eyelet to fasten the fishing line. After several hours searching, I finally located the drone hanging like a bat. It took about twenty shots with the slingshot before I was able to cast it over the right branch. After some vigorous shaking it came tumbling down and is flying today. I do wish I had staged my two teenagers at the bottom with a blanket to catch it, but it was "too cold out" LOL

hope something in this helps

It probably wasn't a tail wind:



I ran some explicit drift simulations assuming constant wind speed and direction, with terminal velocity as an independent variable. The results, for an initial forward speed of 27 mph (12 m/s), a headwind of 8.5 mph and an initial point at an altitude of 1300 ft (400 m):



For the lowest reasonable terminal velocity, this suggests that the aircraft would have been blown around 40 in the direction of the wind. For the highest (and probably not credible) terminal velocity of 25 m/s, the aircraft would have ended up around 40 m in the original direction of travel.

That bounds the possible crash sites to within a 40 m radius circle around the last point:

 

[Mad Mavic]

I must be overlooking the obvious. Searsburg road near the "crash site" is near an east/west heading. Therefore I had the RTH vector just a few points south of west (260) and the wind coming out of the southeast moving to the northwest (140 degrees at .6 mph, hence the quartering tail wind.

At any rate, hopefully the farmer will be open to someone looking around, especially if he had some current video of his landscape

 

[sar104]

I must be overlooking the obvious. Searsburg road near the "crash site" is near an east/west heading. Therefore I had the RTH vector just a few points south of west (260) and the wind coming out of the southeast moving to the northwest (140 degrees at .6 mph, hence the quartering tail wind.

At any rate, hopefully the farmer will be open to someone looking around, especially if he had some current video of his landscape

I'm not sure what you are overlooking. Is there something not clear about the first figure in post #15? The wind is computed as 8.4 mph out of the SW.

Are you looking at the historical ground weather estimates from AirData shown below?



If so then that's worthless at 1300 ft, and nowhere near as useful as the wind field computed from the aircraft ground velocity, pitch and roll.

 

[Mad Mavic]

I'm not sure what you are overlooking. Is there something not clear about the first figure in post #15? The wind is computed as 8.4 mph out of the SW.

Are you looking at the historical ground weather estimates from AirData shown below?

View attachment 53053

If so then that's worthless at 1300 ft, and nowhere near as useful as the wind field computed from the aircraft ground velocity, pitch and roll.

Yes, that's what I used to compile my data; have I got the wrong flight? I will say that I failed to get the weather data at 1300 feet.

 

[sar104]

Yes, that's what I used to compile my data; have I got the wrong flight? I will say that I failed to get the weather data at 1300 feet.

No - it's the correct flight, but it is just the historical ground weather data. You need the computed flight wind map that I linked to above.

 

[bonie for my droniecc]

Still no luck finding it. Sucks