Altitude / terrain newbie question

[Crayons]

Hello. Brand new Australian owner. Only taken out of box, updated firmware and gazed admiringly at new toy so far.

Read some instructions. Watched some videos. I have a newbie question I am hoping for clarity on.

I intend to fly from a 20m high headland... over a cliff, down below where I took off from along beach... plus the terrain rises as land gets further from beach - rising to a 200m high escarpment within 2km.

Noooow.... if I take off from 20m high headland that is the drone's zero point.... and descend to beach - the drone thinks it is .. where vertically?

If I flew inland 1km and find myself 10m above the actual ground level below drone but 70m above where I took off (at the 20m high headland... remember? ...stay with me here) and I hit RTH (set at 40m safety height) ... what will the drone do? Will it rise to 40m above current position? On return will it follow the terrain down so it arrives 40m above headland height? I do hope it wouldn't attempt to go to 40m above original take off point coz that would be ugly.

Any and all clarity greatly received. And also - how does the 'terrain follow' function fit in with all this?

I thank you.

 

[Pushpak]

Hello. Brand new Australian owner. Only taken out of box, updated firmware and gazed admiringly at new toy so far.

Congrats on your new toy

Read some instructions. Watched some videos. I have a newbie question I am hoping for clarity on.

I intend to fly from a 20m high headland... over a cliff, down below where I took off from along beach... plus the terrain rises as land gets further from beach - rising to a 200m high escarpment within 2km.

Noooow.... if I take off from 20m high headland that is the drone's zero point.... and descend to beach - the drone thinks it is .. where vertically?

If you have descended from your home point, it will show negative altitude.
Eg: -10 meters, if you have gone 10 meters below your takeoff point.

If I flew inland 1km and find myself 10m above the actual ground level below drone but 70m above where I took off (at the 20m high headland... remember? ...stay with me here) and I hit RTH (set at 40m safety height) ... what will the drone do? Will it rise to 40m above current position? On return will it follow the terrain down so it arrives 40m above headland height? I do hope it wouldn't attempt to go to 40m above original take off point coz that would be ugly.

No, it will not rise 40m above current point. I will only rise if any obstacles are detected on its way home.

Any and all clarity greatly received. And also - how does the 'terrain follow' function fit in with all this?

I thank you.

The Downward Vision System is utilized in Terrain Follow Mode to maintain a height above ground between 1 and 13 meters. This mode is designed for use on grassland sloped at no more than 20°. It will ascend when slope rises, but will not descend in downward slopes.

 

[Crayons]

Thanks Pushpak. Very helpful.

But...

No, it will not rise 40m above current point. I will only rise if any obstacles are detected on its way home.

... hang on though.... RTH first ascends to preset height, right? ... so if current height is 70m above home point, but only 10m above actual ground... and RTH is triggered (with preset safety height of 40m, say)...the drone thinks it is now 30m higher than it needs to be... what does it do? I am hoping it doesn't ever descend if it's above RTH set height... and would be smart enough to keep at 70m all the way home ?

 

[gregw]

Thanks Pushpak. Very helpful.

But...



... hang on though.... RTH first ascends to preset height, right? ... so if current height is 70m above home point, but only 10m above actual ground... and RTH is triggered (with preset safety height of 40m, say)...the drone thinks it is now 30m higher than it needs to be... what does it do? I am hoping it doesn't ever descend if it's above RTH set height... and would be smart enough to keep at 70m all the way home ?

The RTH height is always above where you originally took off. e.g. your take off point is at an actual 20M altitude, you descend to the beach, which I assume to be at -15M. If your RTH height is set at 40M, then the Mavic will ascend to 20M + 40M before returning home. If, however, you are already above 60M height when you press RTH, then the Mavic will RTH at whatever height it was at when the RTH button was pressed. e.g. if you are flying at 100M above your take off point, then it will RTH at 100M until it is above the take off point before descending.

 

[Crayons]

if you are flying at 100M above your take off point, then it will RTH at 100M until it is above the take off point before descending.

... that makes the most sense and what I hoped would be built in. Cool. Thanks good people. Good job it's so windy outside at the mo or I'd be tempted to move on from the simulator already

 

[Jenee]

Surely you could find somewhere else to fly from where it is over ground and few obstacles until you get some time up on the Mavic and become familiar with it.

 

[Crayons]

Surely you could find somewhere else to fly from where it is over ground and few obstacles until you get some time up on the Mavic and become familiar with it.

Yeah - will do - this scenario just had me wondering (it's literally 30m from front door). I will start at the local park. When no-one is there. Honest.

 

[Pushpak]

Yeah - will do - this scenario just had me wondering (it's literally 30m from front door). I will start at the local park. When no-one is there. Honest.

Good luck and happy flying. Don't get tempted and fly it indoor (bad idea), just because the weather isn't good outside.

 

[Jenee]

Yeah - will do - this scenario just had me wondering (it's literally 30m from front door). I will start at the local park. When no-one is there. Honest.

 

[Michael Ainsworth]

Hi Crayons,

Welcome. Also new to the Mavic and this forum. Live in the 'Gong, some great areas around to video.
My advice would be to read as much as you can on this forum and learn from everyones experiences both good and bad. Hopefully this will reduce potential errors. Don't be in a hurry to go on big trips especially out to sea or in heavy bushland. I believe in baby steps when learning a new skill.
Took mine out for its first flight today at Towradgi , was very windy but the Mavic handled it ok even when it warned me of the wind speed.
I have kept mine in beginner mode which restricts its speed and distance it will fly. I started out low and slow just using the sticks to see how it all works. What I like is that if you just let the sticks go the Mavic will stop and hover, gives you time to decide your next move.
Before taking it up I used the simulator mode in the App to get a feel for things.
Have a good time here and out there.
Cheers
Michael

 

[Malavic]

Hello. Brand new Australian owner. Only taken out of box, updated firmware and gazed admiringly at new toy so far.

Read some instructions. Watched some videos. I have a newbie question I am hoping for clarity on.

I intend to fly from a 20m high headland... over a cliff, down below where I took off from along beach... plus the terrain rises as land gets further from beach - rising to a 200m high escarpment within 2km.

Noooow.... if I take off from 20m high headland that is the drone's zero point.... and descend to beach - the drone thinks it is .. where vertically?

If I flew inland 1km and find myself 10m above the actual ground level below drone but 70m above where I took off (at the 20m high headland... remember? ...stay with me here) and I hit RTH (set at 40m safety height) ... what will the drone do? Will it rise to 40m above current position? On return will it follow the terrain down so it arrives 40m above headland height? I do hope it wouldn't attempt to go to 40m above original take off point coz that would be ugly.

Any and all clarity greatly received. And also - how does the 'terrain follow' function fit in with all this?

I thank you.

As others have pointed out, RTH height is above your home point, so flying down isn't much of an issue.

What I have seen from many crashed Mavics was simply that the RTH height was not high enough. Someone flies the bird behind a building or hill, loses the RC connection triggering RTH and it simply does not rise high enough to pass over the object. The object avoidance won't prevent it from flying into tree branches, fences, wires, etc.

This is not a game to see how close to the terrain you can get on an emergency return to home. Be generous with your RTH value. The downside of a high RTH is wind and the battery usage to climb to the height, which means do all of your risky flying early in the battery. If a RTH will be flying your bird back into the sun, turn off object avoidance. Also, you may have to raise your maximum altitude to have a safe RTH. If you accidentally go behind that 200m escarpment, you'd better have a 215m RTH, even though you wouldn't normally be flying up there.

Good luck, have fun! I love my Mavic, you'll love yours