JJB*
Core User of DJI
Flight distance : 12225059 ft
Netherlands
Offline
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Guorium Posted at 2-12 05:28
A second look on my data reflected something very odd. I matched video with the blue ALT trace. The behavior in vidoe matchs the trace. Trouble is, this whole time before the fast drop, I pushed the throttle stick down! Yet the drone kept climbing. By the flags on the bridge and my memory of the walk there the mini was fighting a headwind on its way to the bridge. Probably encountered some translational lift and I tried to hold the altitude down to fight it. I tried to get some low and fast footage at that time. However, why would veritical speed not reflect the change in altitude? I kept gaining altitude but the vertical speed points down between 1240 and 1340. Does v speed include the speed FC thinks that stick down would cause? Because at 1370 when throttle stick returned to neutral the v speed turned positive which matches what the drone was doing.
BTW I think I finally have a clear picture on what is going on now. I think the period of flight between 1240 and 1340 was interpreted by the mini as unwanted ascend (resulted from translational lift). After that window, GPS speed dropped to zero by me cutting the forward pitch. I kept applying down stick til 1370. ALT between 1350 and 1370 the mini did drop as I intended. Then I return the throttle to neutral (kept yaw) but the mini's self-correction of ALT kicked in and it dropped like a rock trying to restore the altitude perhaps at 1230. The control was not lost. I looked closely at v speed just after 1380 and the change of gradient matched the up-stick command from me. So it was reacting immediately but probably not as quickly as I would like it to in the dire situation. Perhaps my lesson here is to be very aware of how the mini's post-flight altitude correction can be amplified to dangerous level by a combination of gusts and high elevation. Leave plenty of buffer zone and be alert.
Hi Guorium,
Thinking flights over and use all availabile data (video, eyeball mark1, memory and charts) benefits the awareness that flying drones is not that easy. And agree with you ; be alert and don`t fly to the max limits of drones and yourself.
About you question 'Does v speed include the speed FC thinks that stick down would cause? "
AFAIK vertical speed does not taken into account RC stick postions, it reflects the actual vertical speed.
Well, it should reflect only the actual vertical speed, otherwise the FC correction calculations can be useless. But if a drone gets out of its normal flight behaviour due to extreem external influences, do hope that all the programmed algorithms can cope with that too.... ;-)
cheers
JJB
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