My P3P crashed, DJI not cooperating

[msinger]

So if the actual altitude was about 5m at that point (pilot estimate), it would have only risen another meter to reach the minimum RTH altitude which would have put it at 6m (just under 20 feet) actual.

Right -- I'm following along with the pilot estimates. The problem is that DJI is not going to listen to the pilot. They are going to go by data alone. So, we need to use the data we have and somehow determine how it could be wrong.

 

[henick]

.

 

[MikeyOnline]

Something fishy right here imo when considering above avg 36% for 17s and net result loss compared to measly 4 ft loss here.

Throttle stick down though: you'd expect a loss in altitude, no? Those seem reasonable. To me, it looks like the baro is over-sensitive and even though it resets pressure on the ground so that it reads zero at the home point, raising to 20m might make it think 30m. Raising to 30m might make it think 45, and so on. One interesting thing I noted is that right at takeoff, there is a 10s climb averaging 47% up stick. According to the baro, that raised the AC 16m. A vertical rise of 1.6m/s at only 47% throttle seems a bit optimistic.

Mike

 

[msinger]

I'm no expert but simple logic shows that the Phantom DID NOT fly back at 62.3 feet. If it did, it would have flown over the rocks and shrubs into the trees which is NOT the flight path shown in the logs.

You had the throttle at 100% down prior to the impact which caused the Phantom to descend to 54 feet (according to the log). How can we find out how tall those trees are around the crash site?

 

[Chris_P]

There are no trees near the crash site ... Not one. My friend is standing under some trees in the pic I posted earlier. He is 6'1"

 

[henick]

A vertical rise of 1.6m/s at only 47% throttle seems a bit optimistic.
Mike

Nah not me. Max descent is half'ish. Or 47% of max vertical speed. That seems accurate... imo.

 

[MikeyOnline]

I agree and as a skydiver we are trained for altitude awareness as a skill to progress.
I am far from expert with 54 jumps but my first guess was ~50ft also using boat size as point of reference.

That's the other thing. I was wondering what type of boat that is and how tall it is from the water line to the top of the wheelhouse. Looks like maybe 15 feet max. Just measuring it, if you stack 3 more boats on top for a total of 4, you get exactly to the horizon line (which should be level to the camera regardless of where the camera is pointed). 15x4 is a max of 60 feet. And I bet the boat height is closer to something like 12 feet. I'm just going for the max.

Mike

 

[MikeyOnline]

Nah not me. Max descent is half'ish. Or 47% of max vertical speed. That seems accurate... imo.

I was going from the specs that list 2m/s as max vertical ascent speed for the P3P. So if the throttle is linear (it very well may not be), that would put the ascent rate at 0.94 m/s instead of 1.6. That's on the order of how far off the altitude seems to be.

Mike

 

[msinger]

I was wondering what type of boat that is and how tall it is from the water line to the top of the wheelhouse. Looks like maybe 15 feet max. Just measuring it, if you stack 3 more boats on top for a total of 4, you get exactly to the horizon line (which should be level to the camera regardless of where the camera is pointed). 15x4 is a max of 60 feet. And I bet the boat height is closer to something like 12 feet.

I bet it's closer to 30 feet height. The OP probably knows. It's some kind of Carver boat.

 

[Chris_P]

You had the throttle at 100% down prior to the impact which caused the Phantom to descend to 54 feet (according to the log). How can we find out how tall those trees are around the crash site?

I did a quick photoshop comparison using my friends wife since he is slightly hunched over. She is 5'8". Its certainly not dead accurate but its an estimate....

 

[msinger]

Any idea how tall that boat is?

 

[Chris_P]

Any idea how tall that boat is?

Its a Carver 396. Im checking online now.

 

[Chris_P]

Any idea how tall that boat is?

The specs say the "Bridge clearance measurement" is 18 feet. thats the distance from the waterline to the top

 

[Meta4]

I was going from the specs that list 2m/s as max vertical ascent speed for the P3P.

Max Ascent Speed 5 m/s
Max Descent Speed 3 m/s

 

[msinger]

I don't see anything concrete in the log that definitely proves it's not correct. I think the best evidence you would have is a photo at the exact location where the log shows your Phantom crashed -- showing the GPS receiver and no tree within 20+ feet of the crash site. Even then, DJI might just come back and tell you the crash would have been inevitable had it not hit the rocks. And, by that, I mean it's likely your Phantom would have hit a tree had it continued to fly at an altitude of 54 feet back to the home point.

 

[MikeyOnline]

The specs say the "Bridge clearance measurement" is 18 feet. thats the distance from the waterline to the top

That might include the antennas on the top though. And I measured from the water line to the roof of the sun deck on the back, not the top. So my 15 feet might be pretty close.

Mike

 

[henick]

I was going from the specs that list 2m/s as max vertical ascent speed for the P3P.

Mike

I get 3 unless I'm mistaken.

Edit: Yeah meta just confirmed it's 3.

 

[msinger]

So my 15 feet might be pretty close.

Perhaps. Even though, we're just taking a lucky stab at how many boats could be stacked up to make it level with the Phantom. Again, it's most likely not the concrete evidence DJI wants to see.

 

[HWCM]

Where are you standing on the boat deck in the pictures? I can not see you. Did you say you were standing on the platform to hand catch?

 

[henick]

Again, it's most likely not the concrete evidence DJI wants to see.

That's the kicker I think. They seem to be getting more reasonable providing you can provide a reference they're willing to understand.