Altitude Question

[Stazz]

hi, I have the p3s and it’s return to home altitude is set at 30m in Height, next week Im going to do some videos starting at the top of a river valley.
Now when I take off up top of the deep valley and then fly down along the river which is probably 80-100 m deep, If I initiate RTH will the drone just rise to 30m above the lower valley where I’m shooting and then fly towards the original home site and possibly crash into the hillside, or will it elevate to the 30m plus the additional depth to the valley below?
Thanks I’m very interested in the responses

 

[NYroadside]

The RTH setting is relative to your home (launch) point altitude. Based on your current setting, the drone would rise 30m above your home point altitude when RTH is engaged, then return home. If you launch from a higher elevation (above the valley) your current RTH setting should avoid a collision on the return home. Based on the valley depth, if you launched down in the valley, that RTH setting wouldn't clear the hills on the way home. Hope that helps.

 

[Meta4]

If I initiate RTH will the drone just rise to 30m above the lower valley

The reason your Phantom can't do that is that it doesn't know how high off the bottom of the valley it is.
The only height it knows is Home = zero. Everything else is relative to home.

 

[msinger]

when I take off up top of the deep valley and then fly down along the river which is probably 80-100 m deep, If I initiate RTH will the drone just rise to 30m above the lower valley where I’m shooting and then fly towards the original home site and possibly crash into the hillside, or will it elevate to the 30m plus the additional depth to the valley below?

When RTH is initiated, your Phantom will ascend from its current altitude (the altitude currently displayed in DJI GO) up to the set RTH altitude before flying back to the home point.

In this scenario, the current altitude in DJI GO would be a negative value when RTH is initiated since your Phantom would be flying below the altitude where it took off. When RTH is initiated, your Phantom would first ascend up to 0 meters. It would then continue to ascend an additional 30 meters. At that point, the current altitude in DJI GO would be 30 meters (your set RTH altitude) and your Phantom would start flying back to the home point.

 

[Stazz]

When RTH is initiated, your Phantom will ascend from its current altitude (the altitude currently displayed in DJI GO) up to the set RTH altitude before flying back to the home point.

In this scenario, the current altitude in DJI GO would be a negative value when RTH is initiated since your Phantom would be flying below the altitude where it took off. When RTH is initiated, your Phantom would first ascend up to 0 meters. It would then continue to ascend an additional 30 meters. At that point, the current altitude in DJI GO would be 30 meters (your set RTH altitude) and your Phantom would start flying back to the home point.

It will display a negative altitude number? Wow that’s great. That totally makes sense,
Now, I’ve never flown over a cliff before,
I kinda want to stay about a meter above the ground then zoom over the cliff for dramatic effect.
Will there be any barometric events to watch out for once it is suddenly 100 meters high?

 

[msinger]

It will display a negative altitude number?

Only if you descend below the takeoff point. If you fly over the cliff and do not descend, the current altitude will remain the same.

Will there be any barometric events to watch out for once it is suddenly 100 meters high?

Like what?

 

[Stazz]

Only if you descend below the takeoff point. If you fly over the cliff and do not descend, the current altitude will remain the same.


Like what?

Yes I got it, thanks

 

[Stazz]

Only if you descend below the takeoff point. If you fly over the cliff and do not descend, the current altitude will remain the same.


Like what?

Well with auto take off it ascends to 1.2m and stabilizes, doesn’t it kind off create that height using barometric sensing?
I’m just wondering if it would suddenly drop once past the cliff edge and barometric pressures are immediately dropped?

 

[Pharm]

Barometric pressure won’t drop because you went over the edge of a cliff. The things you’ll need to be concerned about:

- Sudden wind/air current changes as you go over the edge (surface friction) due to air currents moving along/up/down the cliff edge.

- The barometric altimeter in the Phantom may not be accurate enough to correctly maintain 1 m altitude over the cliff edge (if you’re relying exclusively on the altimeter for altitude). You’ll need to have a very good line of sight to do that manually (crazy up/downdrafts notwithstanding).

 

[Stazz]

Barometric pressure won’t drop because you went over the edge of a cliff. The things you’ll need to be concerned about:

- Sudden wind/air current changes as you go over the edge (surface friction) due to air currents moving along/up/down the cliff edge.

- The barometric altimeter in the Phantom may not be accurate enough to correctly maintain 1 m altitude over the cliff edge (if you’re relying exclusively on the altimeter for altitude). You’ll need to have a very good line of sight to do that manually (crazy up/downdrafts notwithstanding).

Got it, thanks....