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Time for a fresh Flush of the Toilet Bowl

Joined
Oct 11, 2018
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Olympic Peninsula
#1
Hi all, new member here first post ever. Forgive the old subject (and the length) but I have combed the forum on the Toilet Bowl (TB) subject and haven't found what I am looking for, ...a fix.

I am an old drone pilot and a new H Pro owner for one month now. I love the H and have had no issues with it at all. I recently bought a crashed H for parts because the price was right. When I saw the limited damage I decided to rebuild it as a spare/experimental craft. After replacing 2 booms and a landing strut I calibrated the compass and the Acceleraometer and took the "PhoenixPhoon" for a test flight.

I think I know why it crashed originally, within minutes it started to circle the drain. With no experience of the issue I instantly assumed it to be the dreaded TB effect, heard about it but didn't know what to do about it. I managed to get it to the ground where it did the typical jump-bounce-n'-flip on the front lawn, ...no damage, just some grass stains (and a patch I don't have to mow for a week!).

I discovered on the second flight (minutes later) that turning the GPS off allows it fly and land manually with no issues. Latest firmware allows turning the GPS on/off in flight. So the one thing I do know is TB is GPS lock related, turning it off instantly stops the TB effect mid swirl.

So my question to the group is this, has anyone determined the cause, or better yet the cure for TB? After two years of CS reports and updates from Yuneec it's hard to believe TB is still an issue. It seems to me from what I have read here, it is a Compass Calibration/GPS lock issue. That is a $36 item, has anyone tried replacing it?

If anyone has the answer to the cure please enlighten me. If not, I have an experimental specimen here and I will likely try replacing the Compass/GPS module and see what happens. If it works I'll post the results. If not I'll have a complete list of H parts for sale if anyone's interested!
 
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Joined
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#3
I did not time it, but I did not rush the process, it was long enough for it to acquire at least 14 sats.
My working H can be started as soon as it binds, by turning the GPS off arming the motors and taking off. When it acquires enough sats I can switch GPS on and the entire flight is flawless.
 

Steve Carr

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#4
I did not time it, but I did not rush the process, it was long enough for it to acquire at least 14 sats.
My working H can be started as soon as it binds, by turning the GPS off arming the motors and taking off. When it acquires enough sats I can switch GPS on and the entire flight is flawless.
Well, it's possible it has a faulty GPS module. It's easy to change. Remove the 10 hex screws around the perimeter of the shell, unsnap the two halves and the GPS module is under the gold rf barrier in the top shell. Make sure the wires are twisted before plugging in the new module to the main board.

The H seems to be sensitive on a first flight especially in a new area. It takes 12.5 min to download the satellite almanac data. On the first flight of the day I generally wait for 15 sats before launch. Subsequent flights are nearly immediate.
 
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Steve Carr

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#5
It seems to me from what I have read here, it is a Compass Calibration/GPS lock issue.
I would agree with that. I believe it to be a conflict between the compass and the GPS. It seems when that occurs the flight controller goes into a panic and ignores the stick input. (Forgive my non-tech description) Turning off the GPS is about the only way to regain full control. Your experience and quick thinking save the bird.
 
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#6
Yeah, I noticed the stick inputs were not responding, which made turning the GPS off a little trickyI while I was in panic mode.

And yes, I have had it completely apart -replaced two motor booms and a cracked upper shell, so I did transfer the GPS from one shell cover to another. I was careful to fully seat the connector and keep the wires routed and twisted like they originally were with a brand new RFI shield.

I am a retired EE and still play electronics tech so I am confident in my meticulous repair, but after its original crash breaking 2 booms and strut, anything could have been affected. The PhoenixPhoon was in brand new condition when I bought it -aside from crash damage, and the box boasted the latest firmwere, suggesting it was very new when it crashed, maybe a TB case right out of the box.
 

Steve Carr

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#7
maybe a TB case right out of the box.
It's very possible although you would wonder why it wasn't a warranty repair if it was that new. Did you check the flightlog directory to see how many telemetry files are there? Also, you can upload the telemetry file here for that last flight. It might reveal better information. If you copy it to your pc and add a .txt to the end of the file name it will upload directly to this page.
 
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#10
My working H can be started as soon as it binds, by turning the GPS off arming the motors and taking off.
I'd welcome a correction if I'm wrong about this, but I was under the impression that taking off with GPS manually disabled was a bad idea - are we sure it writes the home point under such circumstances ? Just a thought - I mean I know turning off GPS just means its info is ignored rather than disabled, but I did think we needed it on at the start to establish the home point, right ?
 

Steve Carr

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#13
I'd welcome a correction if I'm wrong about this, but I was under the impression that taking off with GPS manually disabled was a bad idea - are we sure it writes the home point under such circumstances ? Just a thought - I mean I know turning off GPS just means its info is ignored rather than disabled, but I did think we needed it on at the start to establish the home point, right ?
The H does not record a home point. The ST16 is always home. The H Plus and H520 have an option to use either.
 
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#14
I find it interesting that anyone would buy a crashed drone and try to fly it after they performed physical repairs without having all the electronics checked by a repair center. If it crashed once what indicates it won’t crash for the same or other reason on the next flight?

The repeated crashing of repaired drones was quite common in a couple of war zones. Crews would recover crashed aircraft and use parts from them to “repair” other aircraft that were out of service. It should come as no surprise that many of the repaired aircraft crashed on the first flight from the same cause of the crash the parts came from. Those problems did not cease until re-use of crashed components were forbidden, with component serial numbers required to be included in every incident report.

The “good deal” logic in buying crashed aircraft escapes me, especially if there is any intent to reuse flight control and navigation boards
 
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Joined
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#15
Toilet bowl circling is a compass problem.
Best guess is you're location has a different magnetic declination from where it was last flown.
A slow & through compass calibration should reset it.
Or, the compass may not be lined up with the airframe.
Or, the compass is faulty.
 
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