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Forward flight abruptly stops, for a second or 2

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Among the seemingly never ending issues I have with my 520 I have found a new one. In the past few flights the 520 has developed a bad habit of flying forward and then the front of the 520 abruptly bucks up, sometimes once, sometimes a couple of times, before resuming "normal" flight. If you picture flying forward as fast as possible and neutralizing the toggle stick you can all picture how the front of the 520 pitches up as the 520 slows to a stop. This is not what is going on. The up action of the 520 is much more violent. I am pretty sure I am not manipulating the controls to cause what is going on.

I have attached the uploaded Flight Review u log file link and I have included some of the times where you can see the drone model do as I described in the 3D video playback.
:45, :53, :55, 1:54, 2:38, 2:58,
There are several incidents between 2:58 through 3:133:33, 3:43, 35:5
5:21 and 5:34 are good as the track is not overlying other tracks
6:27, 6:30, 7:16 through 7:23, 8:42, 10:48. 11:37

I am hoping that someone experienced in reading the telemetry files will be able to associate the times the incident occurs with information in the telemetry data.

Thanks in advance for any help you can provide.

Paul

 
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Maybe the obstacle avoidance is acting up. Sun rays can also cause this.
 
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DoomMeister

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Maybe the obstacle avoidance is acting up. Sun rays can also cause this.
The sun will only affect a RealSense module. It shouldn’t affect the sonar on most H520’s.

@P Howard are you flying with the OBS enabled or disabled, and do you have RealSense on your H520?

Check the Sonar sensors to ensure there is no dust or dirt on the covers or sensor surface.
 
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DoomMeister

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After watching the 3D view a couple of things come to mind. The first is that it appeared you had the Rate slider at Turtle position as full deflection stick inputs are producing very slow aircraft movements. So that leads to wondering if the winds were gusting at all.

The other thing to consider is GPS quality. If precision is off it can cause jerky flight movements that would be more noticeable when traveling at a slow pace.
 
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Gentlemen,

Thanks for your thoughts. To answer your questions -
Rayray - obstacle avoidance was OFF. Sun rays a possible cause. I wish! This is Vermont. As usual this time of year - overcast.

DoomMeister - OBS disabled. I do have real sense. Turtle mode not engage for entire flight. Actually minimally to see if it made a difference. It did not. Also flew today. Never in turtle mode. Same issue as you will see as I have a couple of videos clips I’ll post later today. As for GPS - we were also flying a Mavic 2 without any issues although I am not sure that tells us anything. Kip index today was 1.3 if that means anything. Also, I have flown at this site numerous times without issues. Sonar sensors are clean.

So I am wondering about 2 things. First - temperature. 28 degrees F today, about the same yesterday, in the teens last week. I don’t see how the temp would cause this but ….

Second, I usually fly with the long range antenna (4Hawks Raptor SR). I took it off and replaced it with antennae that are standard for the 520 as I am traveling soon and the 4 Hawks doesn’t allow. The controller to fit in the case. Possible cause? I’ll find out tomorrow as I plan to put the 4 Hawks back on and see what happens.

Need to run. Videos coming.

Paul
 

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One of our little Tello trainers was doing that. Flying along normally, but suddenly jerking upward at the front, like it got a very momentary "stop" command. Setup a wireless signal booster for it and it's not happened again. One of the Tello's biggest weakness is it's severe lack of range. Not that we're flying them far away, but it's so weak that interference can easily cause trouble, so in some instances we deploy a repeater/booster.

So, what you say about the 4Hawks....could be the right path...
 

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Gentlemen,

Thanks for your thoughts. To answer your questions -
Rayray - obstacle avoidance was OFF. Sun rays a possible cause. I wish! This is Vermont. As usual this time of year - overcast.

DoomMeister - OBS disabled. I do have real sense. Turtle mode not engage for entire flight. Actually minimally to see if it made a difference. It did not. Also flew today. Never in turtle mode. Same issue as you will see as I have a couple of videos clips I’ll post later today. As for GPS - we were also flying a Mavic 2 without any issues although I am not sure that tells us anything. Kip index today was 1.3 if that means anything. Also, I have flown at this site numerous times without issues. Sonar sensors are clean.

So I am wondering about 2 things. First - temperature. 28 degrees F today, about the same yesterday, in the teens last week. I don’t see how the temp would cause this but ….

Second, I usually fly with the long range antenna (4Hawks Raptor SR). I took it off and replaced it with antennae that are standard for the 520 as I am traveling soon and the 4 Hawks doesn’t allow. The controller to fit in the case. Possible cause? I’ll find out tomorrow as I plan to put the 4 Hawks back on and see what happens.

Need to run. Videos coming.

Paul
You had the aircraft apart for the landing gear issue. When you mentioned the difference in antennas on the ST16S it clicked that something may have happened with the antennas on the aircraft. You may want to inspect them to ensure they are not pinched or insulation peeled allowing a short somewhere. I know your flight was very close so I’ll recheck the flight review on the PC and check the RC signal level for low spikes.
 

DoomMeister

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I just checked and the RC signal levels look good. There are a few "RC Lost indicated" blips but they are very brief and do not seem to correlate with the bucking seen.

The only other suggest right now would be to check the controls in the hardware monitor on the ST16S to make sure you are not getting jitter and that they follow your movements.
 
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Thanks for checking DoomMeister.

I failed to mention earlier another event. For about a 30 second span with the 520 10' in the air and about 10-15 feet in front of me it would not respond to a roll input in either direction. Another person was flying it at the time as I was trying to get some video. He kept moving the control stick from 3 o'clock to 9 o'clock and the 520 just sat there unless he gave it any other input (up, down, forward, back, rotate).It suddenly again began to respond to roll input. Just a tidbit to add more confusion.

I uploaded a short video to You Tube. I hope it works. Disregard the first few seconds of the video where the 520 seems to be jumping around. Again, Chip was flying it for the first time.

 
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Interesting discussion. My 520s have always been rock solid in all conditions.

Sounds like a possible intermittent connection somewhere. Such is the bane of all electronic devices, hard to recognize and hard to troubleshoot.

Good luck. Maybe our friends at Vertigo Drones could help you.
 

DoomMeister

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Thanks for checking DoomMeister.

I failed to mention earlier another event. For about a 30 second span with the 520 10' in the air and about 10-15 feet in front of me it would not respond to a roll input in either direction. Another person was flying it at the time as I was trying to get some video. He kept moving the control stick from 3 o'clock to 9 o'clock and the 520 just sat there unless he gave it any other input (up, down, forward, back, rotate).It suddenly again began to respond to roll input. Just a tidbit to add more confusion.

I uploaded a short video to You Tube. I hope it works. Disregard the first few seconds of the video where the 520 seems to be jumping around. Again, Chip was flying it for the first time.

Your description of the way the ST16S was behaving sounds like issues with mixed channels on an H480. Since the H520 does not have the Channel Settings feature I am starting to think the controller may have a polluted Android system.

I recently acquired a used ST16 for an H480 and I created a new model and bound the aircraft and camera to it. I tried several times to get the motors to arm and they wouldn’t. I checked the channel values in Channel Settings and found unusual values in some areas. At that point I did a Factory Reset of the ST16 to return it to all factory defaults. That cured to problem and it now functions flawlessly.

With the issues you have had with the landing gear and other things I think doing a factory reset on your ST16S may resolve these issues. It can’t hurt to do so and may save money in the long run.

Here is a video of the process. Only do the first part where you do the Factory Reset as you are not changing from H+ to H520 or vice versa. Getting to the Android Settings menu may be a bit different on the H520 controller.
 
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Update

I flew again today at the same location before I saw the recent posts. I had swapped the antennae out and put the 4 Hawks back on. I flew a total of 45 minutes doing al the same flight maneuvers I had been doing previously. How many times what I have fondly named the "stutter stop" occur during the 45 minutes? A big 0! My plan is to now put the standard antennae back on and have the 4 Hawks with me and go fly again. If the stutter stop occurs with the standard antennae I shall immediately land and put the 4 Hawks back on and see what happens. If it doesn't stutter stop I think we know the source of the problem but not necessarily the cause of the problem.That may become a moot point, for me at least, as I just won't fly with the standard antennae.

I am hoping to fly tomorrow but the flight area is a large parking lot along the lake. There is a big ice hockey tournament there starting tomorrow so I may have to wait until the weekend.

DoomMeister, I tested the landing gear a few times yesterday and again several times today. No issues. While I am not yet ready to call the issue resolved, I am becoming more and more confident that it has. I think I shall hold off on the factory reboot for awhile and see how things go. At the first sign of a problem I shall proceed with the reboot. Thank you for your input.
 

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If the standard antennas cause the issue to appear again you might consider getting replacements. They are not expensive and would likely be the issue since all was well with the 4Hawks. Likely one or both of the 2.4GHz wand antennas that transceive the Zigbee RC control signals.
 
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Just to give awareness. The camera in H+ and 520 has an important role in the smooth movement. As all 5.8GHz antennas, these in C23 and E90 are suffered from the same problem with broken solder on earth part. I bought a week or two before a smashed H+ for parts, and I'm almost sure, it came to me due to the C23 antenna. It has defective as expected.
 
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Well, so much for my antenna theory. I put the 2 wand antennae and the square antenna back on and flew about 50 minutes at the same location today and not a single stutter stop. I think I’ll put the 4 Hawk antenna back on and wait to see if the issue arises again.
 

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Well, so much for my antenna theory. I put the 2 wand antennae and the square antenna back on and flew about 50 minutes at the same location today and not a single stutter stop. I think I’ll put the 4 Hawk antenna back on and wait to see if the issue arises again.
That is actually good news even though it clouds the issue with stutter flight. We’re there any differences as far as weather, cloud cover, and lighting conditions?
 
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Is it possible that there is corrosion in the stick pots? Could that cause intermittent signals? I always "stir" the sticks before flight, and if that doesn't help then spray the pots with contact cleaner.
 

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There weather was all pretty much the same relative to temp, humidity, cloud cover.
That would rule out possible condensation inside the aircraft body most likely. Keep us updated.
 
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Among the seemingly never ending issues I have with my 520 I have found a new one. In the past few flights the 520 has developed a bad habit of flying forward and then the front of the 520 abruptly bucks up, sometimes once, sometimes a couple of times, before resuming "normal" flight. If you picture flying forward as fast as possible and neutralizing the toggle stick you can all picture how the front of the 520 pitches up as the 520 slows to a stop. This is not what is going on. The up action of the 520 is much more violent. I am pretty sure I am not manipulating the controls to cause what is going on.

I have attached the uploaded Flight Review u log file link and I have included some of the times where you can see the drone model do as I described in the 3D video playback.
:45, :53, :55, 1:54, 2:38, 2:58,
There are several incidents between 2:58 through 3:133:33, 3:43, 35:5
5:21 and 5:34 are good as the track is not overlying other tracks
6:27, 6:30, 7:16 through 7:23, 8:42, 10:48. 11:37

I am hoping that someone experienced in reading the telemetry files will be able to associate the times the incident occurs with information in the telemetry data.

Thanks in advance for any help you can provide.

Paul

Mine does this when I have the obstacle avoidance on, almost every time unless I fly nice and slow with it, always thought it was picking up the props. Never thought to check the connection between the drone and controller.
 

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