Flying between vertical “wall” - risks?

Davros007 · Jul 31, 2020

Hi All,
If I wished to fly at speed through this “crack”, what are the chances of GPS disconnect and and entry into atti mode? How quickly does this occur?
In this poor photo, you can see a gap in the rocks of the cliff on the far side of the beach. I’d like to fly along the beach and through it (at about 1/2 its “depth”, kind of emulating those “wing suit” videos). Possible? Or would it quit GPS and go into the cliff as it went through? I’d guess the gap is about 25m long. In general, what are peoples experiences?
Can you view sat location map in Go4, and pick a time with best layout for a flight?

From above (far right) doesn’t look quite as vertical sided. But kiss drone goodbye if it goes down in the surf! Note the hang-glider ramps on the hill - can’t fly if they’re in use!

Lurch003 · Jul 31, 2020

Don't see why it would lose GPS? It's got a clear view to the sky where the satellites are.

Davros007 · Jul 31, 2020

Lurch003 said:
Don't see why it would lose GPS? It's got a clear view to the sky where the satellites are.

Although it needs a “triangle” for a position? Like an upside-down pyramid, I thought? So a “line” of reception not good?

Hauptmann · Jul 31, 2020

Flying between vertical walls can be very risky. While you won't "lose" GPS connectivity, your GPS will lose accuracy because of Dilution of precision, or DOP. The link below can explain it.

What is PDOP?

www.agsgis.com

Torcan · Jul 31, 2020

The space is probably a lot larger than what can be seen in the photo at that distance.
Prop guards would probably be wise, just in case you were to bump. Just be careful go slow and depending on your skill you should be good.
To get the flysuit effect you could always edit the video to speed up

Good luck and happy flying

Pstik · Jul 31, 2020

This is where you have to fly by visual line of sight not video. There are some good YouTube videos on it.

Dave Maine · Aug 1, 2020

GPS ideally likes a 180 deg sky view. The satellites are scattered everywhere in that dome. Their exact positions are constantly moving during the day, and between days. The drone adapts to this continuously as the signals change, swapping satellites in and out as needed.

The math required, spherical geometry, plus precise time information for your flight will be required to determine the drone’s safety.

Davros007 · Aug 1, 2020

So, how much time do you have with a loss of satellite signal before a Mavic Pro switches to atti mode? And, when this occurs, does the drone stop? Or keep moving forward? In other words, if I was to blast through under a bridge, for example, can I use momentum/forward thrust to get to the other side and regain a signal then keep going?

VenomXts · Aug 1, 2020

that is a pretty wide gap, i would of already flown through it

Trick is just to commit don't stop moving once you are in it.

Meta4 · Aug 1, 2020

Davros007 said:
If I wished to fly at speed through this “crack”, what are the chances of GPS disconnect and and entry into atti mode? How quickly does this occur?

Go and stand in the middle of the slot and look up.
How much of the sky is now blocked by rock and how much can you see?
The number of sats your drone can receive sats from is approximately proportional to the amount of sky visible.
And you need a good spread of sats, not sats that are bunched or in a line.

If that isn't clear enough, you could walk in with your drone and power it up in the middle and see how many sats it gets in there.

hiflyer201 · Aug 1, 2020

Just go for it..make a couple of test runs over the top for timing sake and to calm your nerves.. and then head on thru and make sure you post the results.
I'm pretty sure that DJI loves these photo op's....sales wise..

By the way..that sky looked pretty threatening. Those feeder rotor clouds hanging below the bases don't generally predict fair weather ahead

pelagic_one · Aug 1, 2020

My colleagues from Australia are always proud to say there are creatures out there meant to kill you. Now I see there are flying spots out there meant to kill a drone, too!

But if I were there, I would probably whip out my trusty (and now less-expensive) MP, heed @hiflyer201‘s advice and do a flyover first.

Have fun...I can’t wait to see your video!

Lurch003 · Aug 1, 2020

Davros007 said:
So, how much time do you have with a loss of satellite signal before a Mavic Pro switches to atti mode? And, when this occurs, does the drone stop? Or keep moving forward? In other words, if I was to blast through under a bridge, for example, can I use momentum/forward thrust to get to the other side and regain a signal then keep going?

If you lose GPS, that doesn't mean you'll lose signal so controls will still apply as per atti mode... Just keep going straight!

Dave Maine · Aug 1, 2020

Depends on the drone type - between 3 and 7 seconds.

Davros007 · Aug 2, 2020

Meta4 said:
Go and stand in the middle of the slot and look up.
How much of the sky is now blocked by rock and how much can you see?
The number of sats your drone can receive sats from is approximately proportional to the amount of sky visible.
And you need a good spread of sats, not sats that are bunched or in a line.

If that isn't clear enough, you could walk in with your drone and power it up in the middle and see how many sats it gets in there.

I wouldn’t see much, as I got pounded to pieces by raging surf then eaten by a shark... Unfortunately it’s filled with white water and granite rocks!

Made2Phly · Aug 2, 2020

Pstik said:
This is where you have to fly by visual line of sight not video. There are some good YouTube videos on it.

I have a hard time navigating tight spaces when looking at the drone. I have to navigate through video feed, which is the attached video (less than 30 seconds). That same flight with VLOS did not go well.

DanMan32 · Aug 2, 2020

If it goes into ATTI mode, it still flies and holds altitude, but is subject to wind drift.

The issue you seem to be anticipating is when flight control goes off kilter such as loss of compass accuracy or IMU (gyro/accelerometer) errors or computational errors where then it flies crazy until it decides to go ATTI as a fail safe.