Landing range?

[usefulshrimp]

Hi all,

I had an interesting thing occur and I wanted to get your thoughts on it..

The other day I flew my Mavic about 2100m and all was going great, with full control and perfect video feed. Where I flew it to, there was a paved cul-de-sac, in a completely unobstructed line of sight, next to where some friends were, so I decided to land it so they could get a closer look. It landed just fine and was transmitting video for a few seconds before I lost all transmission.

I've landed it near me many times before and taken off again, but this time that wasn't possible as I couldn't communicate with it at all.

I called my friends, who went and picked it up before I could get over there, and they said it was just sitting on the ground, blinking lights, but the props had stopped spinning (as I would expect).

So, I'm wondering what happened? The only thing I can think of is some sort of shielding from the ground and since it was quite far away, it was enough to sever the transmission?

 

[m0j0]

Well, this is an easy one. You lost signal. I'm betting you could have driven over and it would have come back. That said, I don't think I would expect the Mavic and TX to be connected 1.3 miles away with the Mavic resting on the ground. Would be interesting to see how you maintained LOS between the bird and the TX at that distance. So easy answer. You landed it on the ground and lost connection. If you would have kept it in the air I believe you would have been fine.

 

[usefulshrimp]

Well, this is an easy one. You lost signal. I'm betting you could have driven over and it would have come back. That said, I don't think I would expect the Mavic and TX to be connected 1.3 miles away with the Mavic resting on the ground. Would be interesting to see how you maintained LOS between the bird and the TX at that distance. So easy answer. You landed it on the ground and lost connection. If you would have kept it in the air I believe you would have been fine.

Yes, you're right. The part that's baffling me is why it only lost connection on landing and not when it was in the air? I was on a hill, looking down at the landing area, so I have complete line of sight, even when landed.,

 

[m0j0]

I would think the closer you are to the ground the less likely you are to have a good signal. Consider that the ground itself is probably causing interference with the Mavic's ability to get a good signal. Especially at more than 1.3 miles away. I don't imagine that the Mavic receives the optimal signal when it is lower than the TX.

 

[Mavic22704]

Is there a best way to land far away behind trees where it will lose radio contact as it goes down? One guy said the wind got up and he could not make it home but when it went behind trees while landing in a good spot it lost radio contact it tried to return home causing a crash. Others say do not change aircraft to home position while flying. Does it try to return home when it loses radio contact if you have told it to land using the slider? I want to have a plan in case of a problem. Thanks for any help

 

[Aaron]

I would think if my craft was auto return to home and it wouldn't make it due to wind conditions I would turn return to home off and instead make it hover when signal is lost, then if you tried to land behind trees and it lost connection it would just hover, possibly until the battery went dead and then it would Autoland. I'm not sure but that's what I think would happen. You could also try to flip it in sport mode and then possibly fight the wind.

 

[m0j0]

I Does it try to return home when it loses radio contact if you have told it to land using the slider?

Pretty simple test for that. Take your bird out on a day where it isn't windy. Find a large flat area.. maybe an abandoned parking lot.. Take your bird about 200 yards away. Launch it from a flat area free of obstructions. Let the home point set. Set RTH at 200 feet. Fly it to the parking area you scouted at about 150. Use the slider to make it land. Shut off the TX. It will continue to land or rise to the RTH. You can restart the controller and end the experiment or let it land. That should answer the question.

Your Welcome

 

[Mavic22704]

Pretty simple test for that. Take your bird out on a day where it isn't windy. Find a large flat area.. maybe an abandoned parking lot.. Take your bird about 200 yards away. Launch it from a flat area free of obstructions. Let the home point set. Set RTH at 200 feet. Fly it to the parking area you scouted at about 150. Use the slider to make it land. Shut off the TX. It will continue to land or rise to the RTH. You can restart the controller and end the experiment or let it land. That should answer the question.

Your Welcome

I may have to get more brave to test it lol. Mine is new. Thanks for the help

 

[Foxtrot Uniform]

I may have to get more brave to test it lol. Mine is new. Thanks for the help

I got brave once, or stupid depending how you look at it, and flew, in an open field to 30' high with return to home set at 35'. I then closed dji go 4 app, and disconnected my receiver. Mavic went to 35' for automatic return to home, then landed. just wanted to know if rth really worked in case I lost all connection.
Good to know that if I'm in a situation where I lose connection, I won't tend to panic as much.

 

[Mavic22704]

I would think if my craft was auto return to home and it wouldn't make it due to wind conditions I would turn return to home off and instead make it hover when signal is lost, then if you tried to land behind trees and it lost connection it would just hover, possibly until the battery went dead and then it would Autoland. I'm not sure but that's what I think would happen. You could also try to flip it in sport mode and then possibly fight the wind.

Thanks, it does seem that hover would better at signal loss than landing. Some say changing settings while in flight is not good. It would be good if it would land when I tell it to even if it lost signal on the way down. I may test it.

 

[Aaron]

If it lost signal on the way down it's either going to return to home or Hoover I think at least have it hover would give you a chance to jump on your car and try to get to it. And if you don't get there in time it should Autoland where it's at once the battery gets to a critical level hopefully it's not over water. Always try to fly into the wind as well this makes return to home easier.

 

[aesculus]

Yes, you're right. The part that's baffling me is why it only lost connection on landing and not when it was in the air? I was on a hill, looking down at the landing area, so I have complete line of sight, even when landed.,

I did the same thing four days ago just messing around and testing range limits. I'm in a rural area and there is a seldom used gravel road near my house in complete VLOS. I flew across the field to the road and planned to land and then start the motors and take off again. I had an excellent connection, no video dropouts whatsoever. I was 3777 feet away and descended onto the middle of the road. As it touched down, altitude was -3.3 feet. Once on the ground I immediately lost signal. I held the RC high and tried to position the antennae to re-establish contact, but it never did. I probably could have gone up to the loft in my barn and stuck the controller out the window and re-established connection, but instead I jumped in the car and drove down to the road. The video kept rolling and 5 minutes later my car came rolling into view

I was surprised at how quickly the signal just dropped off. 3 vertical feet meant the difference between a perfect signal and nothing at all. I live in very flat countryside. But I knew immediately that even though the terrain is flat, when the Mavic is landed, its antenna is so low to the ground that the ground itself gets between the Mavic and the RC. It was a good lesson to learn and I'm glad I did it at home.

 

[alexanderguelph]

Thanks for sharing. This is something I wondered about but hadn't yet tested.

 

[Mavic22704]

I did the same thing four days ago just messing around and testing range limits. I'm in a rural area and there is a seldom used gravel road near my house in complete VLOS. I flew across the field to the road and planned to land and then start the motors and take off again. I had an excellent connection, no video dropouts whatsoever. I was 3777 feet away and descended onto the middle of the road. As it touched down, altitude was -3.3 feet. Once on the ground I immediately lost signal. I held the RC high and tried to position the antennae to re-establish contact, but it never did. I probably could have gone up to the loft in my barn and stuck the controller out the window and re-established connection, but instead I jumped in the car and drove down to the road. The video kept rolling and 5 minutes later my car came rolling into view

I was surprised at how quickly the signal just dropped off. 3 vertical feet meant the difference between a perfect signal and nothing at all. I live in very flat countryside. But I knew immediately that even though the terrain is flat, when the Mavic is landed, its antenna is so low to the ground that the ground itself gets between the Mavic and the RC. It was a good lesson to learn and I'm glad I did it at home.

How did you have fail safe set if signal was lost? Thanks for the information.

 

[diabox]

The reason that you lose signal once landing on the ground is because of fresnel zone obstruction. The fresnel zone in a wireless signal extends all around the direct line of site between a transmitter and receiver. Obstruction of the fresnel zone of more than 30-40% will start to cause signal loss. As the Mavic is less than 6" off the ground the whole bottom half of the fresnel zone is blocked. Google fresnel zone clearance to learn more.

 

[Fletcher500]

I got brave once, or stupid depending how you look at it, and flew, in an open field to 30' high with return to home set at 35'. I then closed dji go 4 app, and disconnected my receiver. Mavic went to 35' for automatic return to home, then landed. just wanted to know if rth really worked in case I lost all connection.
Good to know that if I'm in a situation where I lose connection, I won't tend to panic as much.

A plus on RTH for your quad. Mine has been out 5 times. Works like a dream, but I still can't get the RTH to work. Probably a newbie issue, so I will keep trying.

 

[aesculus]

How did you have fail safe set if signal was lost? Thanks for the information.

It was set to RTH at 40m. But it was in its landing phase when it lost connection, so RTH did not engage.

 

[Mavic22704]

It was set to RTH at 40m. But it was in its landing phase when it lost connection, so RTH did not engage.

Thanks, I wonder if I use the app and tell it to land but it loses signal on the way down would it still land or try and return home?

 

[aesculus]

Thanks, I wonder if I use the app and tell it to land but it loses signal on the way down would it still land or try and return home?

That's a good question. I don't use the land button on the app much so I don't really know. I suppose it would depend on how high you were when you initiated the land. If I get an opportunity tomorrow I'll try landing and turning off the controller in my back yard. It's big and has plenty of room.

 

[Mavic22704]

That's a good question. I don't use the land button on the app much so I don't really know. I suppose it would depend on how high you were when you initiated the land. If I get an opportunity tomorrow I'll try landing and turning off the controller in my back yard. It's big and has plenty of room.

Thanks, let us know. I just feel there may come a time when I want to land far away because of a sudden wind or bad battery and I will not want it trying to fly home and crashing. I live in east texas with a lot of tall pines that block radio signals really well.