endotherm
First Officer
Flight distance : 503241 ft
Australia
Offline
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O.K., I'll forgive you this time.
I read the thread on Phantom Pilots (which also suffers from hijackers...). My first observation of the video is that the aircraft seems to invert and slide into the water directly -- there is not the typical tumble in all x-y-z axis movements one would expect. It's almost like it was grabbed by a large raptor and lowered to the water. I can't say that I have examined a fall from the sky that appears to be so smooth and direct.
I tried to look at the flight logs, the link to Phantom Help doesn't point to your flight, and the AirData link doesn't share the kml and csv options, which is what I need for a proper analysis. If you could fix that up and repost it, it would be helpful.
Flying backwards is not a problem and aerodynamically it is no different than flying in any lateral direction in a symmetrical "X" configuration quadcopter.
You complained of getting "Motor Idling (Loose or Missing Propeller)" errors. This message is a result of examining the loads on the motors against the speed of rotation. Usually you get this on the ground spinning the motors with no load (props) fitted. The calculation would be based on using genuine DJI props, which are typically well balanced with little to no difference in weight. Using third-party props could well cause this relationship to change from what is expected, resulting in an error message. DJI seem to have tightened tolerances in later firmware releases so they seem to be less forgiving of an imbalance and pop up a warning more often. That doesn't mean it is immediately likely to crash, just that it is out of tolerance. The same effect could be caused with genuine props, but ones that have sustained dings and damage from crashes, or having been sand-blasted by flying in "hostile" environments and worn down. The first time I saw this, the person had mixed up P2 and P3 props and was getting the message all the time, even though they were tight and it appeared to fly well. The P3 uses 9450 props and the earlier props were 9443. The props weren't as wide and didn't droop as much as a P3 prop. As such the weights would have been way out of tolerance, explaining why he was constantly getting error messages. In your case, who knows what weights and drags your third-party CF props have. DJI like to control what you use with their equipment (a bit like Apple) -- they already prevent you using non-genuine batteries so that the flight characteristics are a known quantity. Perhaps the constant warnings are to discourage you from using non-genuine products?
I see you have recovered the aircraft and found the props were still attached (and presumably undamaged?). Were the motors able to be rotated freely, or had any of them seized up? If you are able to power up the aircraft, you can extract the aircraft internal flight log. It is a DAT file that will show up if you enable data mode from the Go app, and read it off the aircraft via the front USB port next to the front name plate. This will contain additional data beyond that which we normally examine via Phantom Help etc. It would contain motor speed and loads which may correspond with motor failure/prop loss/abnormal battery discharge etc. This might provide more information to determine a cause if the standard flight log is unsuccessful. This is the same log that DJI examine when you send the aircraft in for repair and warranty claims. It is stored on an internal sealed SD card and is unlikely to have been tampered with, so they trust it more than you sending in any old flight log.
If you can start by fixing the links to a normal flight log with access to kml and csv data, we can start there.
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