Signal strength and ability

[KingRat]

Just pondering, because I have an awkward job to carry out. I have been and walked the area to get a good idea of the lay of the land. There is a leaking roof, it is in a sunken part of the roof area of a large building and due to the proximity of other buildings around there is no possibility of getting a cherry picker anywhere near. In fact they are going ot have a hell of a job getting scaffolding erected as there is so little room.
Anyway, my concern is, how much radio shadow is the building likely to cause me - I have been asked to put the drone up to have a reconnaisance of the damage where the leaks are. It means standing under the builing in a narrow passageway, which is the ONLY access for some distance and it is surrounded by other high walled buildings with no windows or roof access (my first line of enquiry in the area). It is a mess of buildings and it is a heritage location and their budget is miniscule, I am doing it as a volunteer, they are struggling to keep the place open (please don't preach to me about giving my work away, sometimes you do it because you want to help).

I am going to lose visual, there is no question. Unless you remain about 80 feet above the roof you will lose visual because of the proximity of the walls of the other buildings around, and the building itself. My real concern is once the drone goes 'over the lip of the building and out of sight' (see the inverted commas, I hope you can visualise the situation) I will be flying on instruments only, as it were. How well does the control signal and video feed go round corners? Does anyone have any experience please? I was going to have a go today but it is howling out there, despite being dry it is too windy for any kind of flight, so I am using the time to get a better understanding of this 'hidden drone' capability. It will be flying up and over the edge of the building with me hemmed in underneath. The other option is to take off about 3/4 mile away and fly in, but I will be blind then too, just further away.

It is a difficult situation, because it isn't the main roof that goes round on four sides of a rectangle, it is the sunken roof between the four ridged rooves, and it is going to need exploring from fairly ow down over the sunken bit - it is a good 30 feet below the ridges of the surrounding rooves. If I could get on the roof space of one of the neightbouring buildings it wouldn't worry me, but that is just not possible, the question has already been asked - and the water is still coming in.

So, over to you guys....

 

[Phantomrain.org]

We love taking risks with our drone, but this mission of yours has a lot of variables and its more a suicide mission as it stands now until you do some scouting missions.

Concerns:
Loosing GPS signal and entering into Atti mode
Loosing Transmission signal and Video feed and flying completely Blind.
Forced landing on the building and a reset of the home point.
and of course the Water itself.

Seasoned pilots struggle with Atti mode and you dont have a lot of room to breathe .
Flying completely blind leaves you only 1 direction and that is straight up if your prepared for it.
A forced landing could put you right into the flood and reset your home point.
RTH point triggering , is also something that should be expected.

Some scouting missions will go a long way to test your limits of the flight both from under and far.
I would also be tempted to use a Mavic 2 Rescue Jacket for any forced landings around or on the water.

Phantomrain.org
Gear to fly your Mavic 2 in the Rain and Float on Water.

 

[MAvic_South_Oz]

Just make sure RTH is set to a height say 10m over the tallest part of the surrounding buildings.
I'd take it up next to such a place, with camera dead centre, get to the height and add another 10m (30') to that.

If you lose LOS signal you will go up to RTH alt, probably regain signal promptly, then cancel RTH and continue the mission at a slightly higher altitude.
With the pro you should be able to shoot 4k and zoom in in post to see a bit more detail if needed.

Absolutely no chance you can work from a nearby building roof to fly / operate from ?

 

[KingRat]

Just make sure RTH is set to a height say 10m over the tallest part of the surrounding buildings.
I'd take it up next to such a place, with camera dead centre, get to the height and add another 10m (30') to that.

If you lose LOS signal you will go up to RTH alt, probably regain signal promptly, then cancel RTH and continue the mission at a slightly higher altitude.
With the pro you should be able to shoot 4k and zoom in in post to see a bit more detail if needed.

Absolutely no chance you can work from a nearby building roof to fly / operate from ?

Correct. These opportunities have already been explored. I think I shall just have to stay at a height I can see it and crop in to the RAW images (video isn't needed, not really) as best I can. This I have already thought of, but I wondered if I was brave and ventured down into the lowered area of the 'enclosed' roof flying by the screen the drone would still respond, but I have a feeling the buildings are going to block any kind of signal transmission/reception unless direct line of sight from controller antennae and the drone is maintained. It is certainly a very limiting situation and not without risk. I won't be flying it today with the wind we have - 25 knots with stronger gusts. I expect the eddies in the buildings will be really flukey and I am not prepared to take any chances - hence my questions.

 

[Capt KO]

Suicidal.! Signal will be lost around the first blind corner so you and your drone will be….a new lesson learned post. Might hire a kid with an FPV racing drone to give it a try. They are used to tight indoor spaces without gps and flying out of sight. Good luck

 

[KingRat]

Suicidal.! Signal will be lost around the first blind corner so you and your drone will be….a new lesson learned post. Might hire a kid with an FPV racing drone to give it a try. They are used to tight indoor spaces without gps and flying out of sight. Good luck

See my reply above yours.

 

[old man mavic]

@KingRat as noble as your reasons for the flight are, if it all goes south ,are you in a position to be without your drone
sometimes the risks are just to great and you have to walk away

 

[KingRat]

@KingRat as noble as your reasons for the flight are, if it all goes south ,are you in a position to be without your drone
sometimes the risks are just to great and you have to walk away

Hence me asking before finding out the hard way. Do you think I am made of money?

The good news is, perseverance has paid off and I have gained access to a flat roof opposite, so can fly level with the ridge and just zoom in from there with no risk of losing line of sight.

 

[MAvic_South_Oz]

but I wondered if I was brave and ventured down into the lowered area of the 'enclosed' roof flying by the screen the drone would still respond, but I have a feeling the buildings are going to block any kind of signal transmission/reception unless direct line of sight from controller antennae and the drone is maintained. It is certainly a very limiting situation and not without risk. I won't be flying it today with the wind we have - 25 knots with stronger gusts. I expect the eddies in the buildings will be really flukey and I am not prepared to take any chances - hence my questions.

I think if weather is ok to fly lower, low wind especially, then give it a shot.
Maybe test RTH first with a manual RTH while in sight, when it behaves appropriately, stop RTH and continue mission lower.

Be sure to double check failsafe RTH and safe altitude needed, height of structures / antenna etc plus the safety margin.
Do the quick altitude / RTH set check next to the building first, a quick up and down during pre flight checks.

As you sescend, keep and eye on signal strength, keep a watch for screen flickering.
If you lose video, be prepared to do a RTH or just left stick (throttle) up to bring it up.

Are you close enough to hear the full throttling motors when outside the building perimeter ?

Suicidal.! Signal will be lost around the first blind corner

Not to argue your sentiment, but I'm not so sure.
I've flown behind things, signal never lost.

I think it will depend on the drone and how good the occusync protocol is for that drone / controller setup.
The M2 is like the M1, very very solid signal.

@KingRat please let us know how you go.

 

[Ralph thompson]

Can you give us the Lat/Long so we can view it on Google Earth? Surprising that there's no access to the roof from inside the building unless its a simple private dwelling with a peaked roof. I have done a lot of roof inspections, flat, mansard and peaked and although some can be challenging, theres always a way, although I'd pass on sky scrapers. Taking still raw photographs would be the best (not video) then you can zoom in post. Also the further you stand back the more you can fly over the centre of the roof but as LOS starts to disappear then just increase altitude a little and continue further but its not going instantly disconnect if you progress too far. But depending on the size of the roof area and obstacles on the roof, you should be able to get good images, you don't have to shot straight down, angle the camera and look across the roof. If there are obstacles then move around the property and launch the drone from the other side. If there are lots of tall buildings around be very careful of wind, strongly recommend a none windy day, buildings in say downtown areas can create complex wind currents. Checkout this video Urban Airflow: What Drone Pilots Need to Know
Also use a good checklist beforehand to ensure you're not starting with a flawed mission.

 

[MaxE1955!]

Sometimes you just have to accept that something is beyond your skill set. Unless you’re willing to SACRIFICE your equipment, there is no since in going into something your not ready tackle. If money is no object and you want a new bird, go for it!

 

[KingRat]

Thanks for the constructive comments. I completed the mission, video and stills, delivered to the client yesterday. I managed to get access (no permission) to a flat roof opposite. The building is disused and I have no idea how rotten the roof I was standing on is! I climbed the fire escape and climbed over the spiked fence.... it gave me an almost level viewpoint. The resulting video was over 3MB and the jpeg stills were another 2.5MB and the client is over the moon.

I am still not certain I would have been able to maintain signal from ground level. Old, 3ft thick, stone walls as they built in the 15th century are a bit of a barrier. The jury is still is still out if the occusynch signal will bounce around enough off the other buildings, many of them and the neighbouring ones on 2 sides are so close you cannot walk between them, you can't even squeeze between sideways and breathing in. I don't think people in America have any idea of what building is like in the old towns of the Mother Country.

 

[MAvic_South_Oz]

I don't think people in America have any idea of what building is like in the old towns of the Mother Country.

True, though @Mazdaman323lx (UK member) has posted quite a few videos of old castles / ruins, with hugely thick walls at the base, some I estimated to be 10' thick stone blocks.

 

[Mazdaman323lx]

Nah , you'll be fine . As MAvic South mentioned , signal degradation isn't going to be as bad as you expect ,(see below) unless your flying a Mavic air or something not Occu sync equipped

And out of the morning mist loomed a Castle...................

My take on the spectacular " Castle Lohort" in County Cork Ireland

mavicpilots.com