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Troubleshooting loss of control glitches

Old 11-22-2015, 11:28 PM
  #1  
Swiss Flyer
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Default Troubleshooting loss of control glitches

I was flying my Apprentice S 15e today in good conditions. What I noticed after a few minutes is that I would get a 2 sec loss of control together with a throttling down before the plane recovers and flys normally again. I flew for a few minutes and this would happen intermittently. I initially suspected an issue with the battery, or overheating speed controller so brought her down and had a look. The Speed controller was fine, just slightly warm to the touch. So I replaced the battery pack for a fresh one and took her up again and exactly the same issue. I maintained good airspeed to rule out a stall or other aerodynamic causes.

I am flying with a Spektrum DX6 and the SAFE receiver so not sure radio interference could be the cause, which would either point to a glitch with the receiver or the speed controller. What seems to point to the latter is that when the glitch happens the motor cuts too.

Any other thoughts?
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Old 11-23-2015, 12:33 AM
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Make sure you are not pointing the Tx antenna directly at the aircraft during flight. The signal is strongest of the side of the antenna and weakest off the tip. Try and always have the side of the Tx antenna facing the aircraft.
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Old 11-23-2015, 01:32 PM
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Could be brown out (low voltage to the receiver from the ESC). That would also cause the loss of control. Anything that might cause an abnormally high servo draw like a stuck control surface or damaged servo?
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Old 11-23-2015, 01:34 PM
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If motor is cutting out as well ... this would suggest a total power failure ...

If it was just ESC being overwhelmed ... then quite often the motor starts pulsing in rpm ... my F15 used to do this on summers day when temp was hot. If it's BEC ... then the loss of control would incur a reboot time. Depending on how failsafe is set .. you could have motor cut out and all controls to neutral or induced spin to prevent fly-away ... as example.

I think you need to analyse carefully exactly what happens when you lose control. If it's total ... then usually the model would do something daft and you could be in for the Plastic Bag Walk of Shame ..
If its just a motor shut down .. it could still give you control ...

With SAFE ... you may be masking what happens by it initiating failsafe ? Then you have a model that flies on awaiting reboot or regained control.

Last point ... I have read of SAFE actually losing control .... but thought this was a thing of the past ..

Like I suggest ... a sit down with a beer and think carefully all actions and observations when it happens. Is it same point in the field ... etc. etc.

The antennae orientation is a fact - but unlikely as our Tx and Rx's are usually not flown to extreme where the orientation reduction will lose lock-on. Unless an intermediate solid obstruction or wire mesh fence is in direct line to model.

Nigel
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Old 11-23-2015, 01:44 PM
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Just an aside ... one of the reasons I video so many of my flights ... its the brst diagnostic tool there is. Honestly - 90% of the time - what you think is cause is actually not.
You instantly react and decide xxxx is the reason. You watch video afterwards .. I slow down frames during the incident and analyse every detail I can ... usually you see something that you were never aware of.

A very good example is my Biplane vertical into the runway from an inverted pass. Like many have done and many will do ... I assumed it was wrong way on elevator ... pulled UP instead of DOWN. On the video I shout same.

Video clearly shows that the model made no deviation or control at all ... despite my waving sticks ... she went straight as an arrow in ...
Elevator servo had a fault and locked ...
Without that video - I would never have known. Swapped out the servo ... rebuilt her and years later she is still flying.



Before anyone comments on the full throttle ... it was actually about 70% throttle in early bits because the engine was only third flight ! Still new and unreliable at bottom end.
Nigel
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Old 11-23-2015, 05:13 PM
  #6  
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Most ESC's will shut off the motor if there is no signal from the receiver. That could be either from a brown out reboot, or signal loss. Spektrum failsafe disables the motor so it could be signal loss or brown out. Either way, the model is entering a failsafe condition.

I agree that at visual range, signal loss due to antenna orientation is rare on a otherwise normally functioning system.

A ground range check might reveal problems with signal strength.

If the OP can swap out the ESC with one that is known to be good, use a receiver battery pack or UBEC that would eliminate brown out as a cause.
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Old 11-23-2015, 05:35 PM
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Originally Posted by pmullen503 View Post
Most ESC's will shut off the motor if there is no signal from the receiver.That could be either from a brown out reboot, or signal loss. Spektrum failsafe disables the motor so it could be signal loss or brown out. Either way, the model is entering a failsafe condition.
True but if Rx is still powered and no signal rec'd from Tx ... the failsafe may be set badly ... if at all.
Many Rx's have a default failsafe of last command hold. Its up to user to change.

I agree that at visual range, signal loss due to antenna orientation is rare on a otherwise normally functioning system.

A ground range check might reveal problems with signal strength.

If the OP can swap out the ESC with one that is known to be good, use a receiver battery pack or UBEC that would eliminate brown out as a cause.
I cannot help but think that this may be a recurrence of the SAFE dropping out that some reported in the early days ... basically a lack of response from the model and then coming to life again. I find it interesting that 2 sec's is a long time actually in RC terms and in many cases if a total loss of control would result in carnage. I feel there is more to this than simple 'out' ...

Nigel
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Old 11-23-2015, 06:06 PM
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Originally Posted by solentlife View Post
...The antennae orientation is a fact - but unlikely as our Tx and Rx's are usually not flown to extreme where the orientation reduction will lose lock-on. Unless an intermediate solid obstruction or wire mesh fence is in direct line to model.

Nigel
I've had it happen with my own gear and seen it happen with the model mentioned by the OP.

Not sure what extreme you speak of. If the Tx antenna is pointing at the aircraft the signal to the aircraft is weakest. I've seen lots of people fly this way and see it frequently on videos.
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Old 11-23-2015, 08:20 PM
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Originally Posted by Turner View Post
I've had it happen with my own gear and seen it happen with the model mentioned by the OP.

Not sure what extreme you speak of. If the Tx antenna is pointing at the aircraft the signal to the aircraft is weakest. I've seen lots of people fly this way and see it frequently on videos.
Did I disagree ? No.

BUT ... how often do you see such situation and loss of control ?

No matter what orientation you have of Tx and Rx antenna .............. I g'tee that during the flight you will have the worst possible occur during the flight ... but do we lose the model ? No.

On most of my models where only 4 ch's are needed I use the FrSky 4ch Rx where it only has the single short antenna. I fly to extreme range of view of the models with no problem ... often my FrSky Tx antenna is angled down or up ... depending on whether I notice or not .... any difference in model control ? No.

Sorry but it's an item that gets mentioned but I have no evidence so far it actually happens ...

Nigel
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Old 11-23-2015, 09:10 PM
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Of course, on Frsky you have RSSI and receiver voltage telemetry. If you have a Taranis and logging turned on, you can check the log second by second and see what was going on. If you set up voice warnings you'll hear as soon as either gets low.

I'm with Nigel on the antenna orientation. I just don't ever see that at our busy field when flying LOS. Heck, many new transmitters have a fixed antenna(s).

The OP's radio or receiver may have a problem, a range check might reveal that. If that's OK then receiver power is the next thing to rule out. I don't know much about SAFE but if you suspect that then turn it off or try another receiver.
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Old 11-23-2015, 11:21 PM
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Thanks guys, I have another Spektrum (non SAFE) receiver that I will try out as well as a spare ESC. It does actually sound like an in-air reboot of the system. To be perfectly honest I find SAFE to be more trouble than its worth, I've had two previous crashes as a result of it and will be glad to move on now that I am more confident with my flying skills.

However what was interesting is that when the system sprung back into life it did the same as when you press the 'Panic' button i.e. it auto levelled the wings.
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Old 11-24-2015, 01:37 AM
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Originally Posted by solentlife View Post
...BUT ... how often do you see such situation and loss of control ?

No matter what orientation you have of Tx and Rx antenna .............. I g'tee that during the flight you will have the worst possible occur during the flight ... but do we lose the model ? No….
Well it does seem you are disagreeing with me. I guess you didn't really read my post. What I said was that I have had loss of control when the Tx antenna was pointing at the aircraft, restored once the side of the antenna faced it, and I have seen videos posted of the Apprentice crashing due to loss of control and it was clear from the video that the Tx antenna was pointing directly at the aircraft. It's also important to note that in Spektrum manuals it warns against pointing the antenna at the aircraft.

I don't know why I get a fight, not just from you, when ever I mention this. It is a real concern and can definitely cause loss of signal. Was it a factor in this crash? I have no idea. I simply mentioned it so the OP might use it to possibly diagnose the cause.
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Old 11-24-2015, 04:05 AM
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Pointing the transmitter antenna at the receiver will reduce range drastically. From perhaps two miles to a half mile!
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Old 11-24-2015, 07:34 AM
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Originally Posted by Turner View Post
Well it does seem you are disagreeing with me. I guess you didn't really read my post. What I said was that I have had loss of control when the Tx antenna was pointing at the aircraft, restored once the side of the antenna faced it, and I have seen videos posted of the Apprentice crashing due to loss of control and it was clear from the video that the Tx antenna was pointing directly at the aircraft. It's also important to note that in Spektrum manuals it warns against pointing the antenna at the aircraft.

I don't know why I get a fight, not just from you, when ever I mention this. It is a real concern and can definitely cause loss of signal. Was it a factor in this crash? I have no idea. I simply mentioned it so the OP might use it to possibly diagnose the cause.
I did read and I did note you say you had loss of signal. And its no fight --- this is a discussion and I know you are reasonable and can discuss ....

The fact of antenna is accepted and as I said I believe true - but given the range we usually fly in - should not unless the radio is a park fly 300m job or Rx is poorly sited - should not really be a problem.
Various radios have fixed vertical Tx antenna unlike FrSky for example that is hinged. Given the angle most people hold their radios ... the fixed straight out of case job must be worst offender ?

The other fact is that given we are flying in 3 dimensions ... at numerous times during the flight - the orientation will be bad.

I am not saying ignore it - we should always orientate to best advantage. That brings in question - what orientation vs attitude of model ? Maybe we should set up that when model is flying towards us and Rx antenna is probably at worst change Rx antenna to get best reception ?

Again it is a discussion and guy wants ideas to try and find out why he lost signal - so all posts are valid.

Nigel
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Old 11-24-2015, 07:38 AM
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Originally Posted by kyleservicetech View Post
Pointing the transmitter antenna at the receiver will reduce range drastically. From perhaps two miles to a half mile!
Isn't that like saying 'how long is a piece of string ?'

A certain common brand of radio has a fixed vertical straight out of case antenna ... which has to the worst possible given the angle we tend to hold our radios. I've never seen anyone hold theirs absolutely vertical yet ! Normally they are nearer horizontal....

Nigel
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Old 11-24-2015, 02:35 PM
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Originally Posted by solentlife View Post
Isn't that like saying 'how long is a piece of string ?'

A certain common brand of radio has a fixed vertical straight out of case antenna ... which has to the worst possible given the angle we tend to hold our radios. I've never seen anyone hold theirs absolutely vertical yet ! Normally they are nearer horizontal....

Nigel
My Spectrum DX9 transmitter has two antennas. One vertical, one horizontal inside the handle. Yup, I've looked inside my DX9.

Spectrum indicates the transmitter electronics rapidly switches between the two antennas.
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Old 11-24-2015, 03:13 PM
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Originally Posted by kyleservicetech View Post
My Spectrum DX9 transmitter has two antennas. One vertical, one horizontal inside the handle. Yup, I've looked inside my DX9.

Spectrum indicates the transmitter electronics rapidly switches between the two antennas.
Did I say Spektrum ?



Spekie is not only one to have vertical antenna ... and I applaud that later have the dual antenna as you illustrate.

I often wondered about ways to connect my internal handle antenna in my 9xr as well as the external ... I do not want to remove the external .. I get a certain comfort from actually seeing it there.

Nigel
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Old 11-24-2015, 04:20 PM
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Here's a solution that could help many TX's...........:

https://www.youtube.com/watch?v=2zBfEhq0jeY

And void your warranty...........
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Old 11-24-2015, 04:22 PM
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Instead of all the speculation (and bickering), couldn't antenna orientation as cause for this problem just be ruled in or out with a range test?
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Old 11-24-2015, 04:23 PM
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Connection shorts can be a major culprit. Turn on the system (with prop removed) and jiggle every bit in the plane. You might be surprised.
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Old 11-24-2015, 05:09 PM
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Originally Posted by WAMBO View Post
Instead of all the speculation (and bickering), couldn't antenna orientation as cause for this problem just be ruled in or out with a range test?

Ahhhhh Common.........then you'd take all of the fun out of it for a couple of our "senior" members..........
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Old 11-24-2015, 05:12 PM
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Agree with maxflyer...I had an antenna shield (ground) break and just barely touching the "pad". As I moved the connection would intermittently move and I would have inconsistent control of my planes. While I'm not the best pilot around...I knew I was not as bad as the issue made it seem.
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Old 11-24-2015, 05:38 PM
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Originally Posted by solentlife View Post
Did I say Spektrum ?



Spekie is not only one to have vertical antenna ... and I applaud that later have the dual antenna as you illustrate.


Nigel
LOLOL

My Spektrum DX8 transmitter has that single antenna inside that dreaded hinged plastic antenna housing. Grab the transmitter by that plastic POS, and it will break!

Even with that DX8 though, I've got the Spekie signal monitor thing. And it never showed a loss of signal on a number of flights with one of my giant scale models.
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Old 11-24-2015, 06:18 PM
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Originally Posted by WAMBO View Post
Instead of all the speculation (and bickering), couldn't antenna orientation as cause for this problem just be ruled in or out with a range test?
No bickering at all ... just throwing ideas around ... everyone has a view on it ... and who's right ? Only the person affected can find out by eliminating each possibility till he gets solution. Maybe one of the seemingly daft or wrong ideas turns out to be the one ...

As to Senior ? What's that ? Humour ? Sarcasm ? Not really Wattflyer is it ...

Range Test - mmmm that all depends how you conduct it. It also depends on the gear.

Some gear talk about 30 paces range ... some talk about 60 ... 90 ... etc. You have to check your brand and what is recc'd by that manufacturer. I know with my JR Propo and Futaba's on FM - they all exceeded by large margin range checks and of course being FM were not so affected by line of sight obstructions as 2.4.
My 9x and 9xr's all exceed range tests by a large margin also ... I mean it's a BIG margin. Even on the little Parkfly 4ch Rx ... I can walk for at least 200m with reduced Tx power and still have total lock on. In fact I gave up trying to get it to fail and now use them in all my 4ch stuff ...

Maybe deliberately trying to 'fail' the lock is worth a try ... antenna pointing wrong ... Rx antenna shielded in model by CF / metal ... other side of chain link fence ... solid walls with metal parts ?

Who knows .....

Once OP gets to find out what it is ... I know I for one am very interested to know.

nigel

Just an 'Old fart' trying to help ...
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Old 11-25-2015, 02:35 AM
  #25  
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Default Range Test?

A comparison of range tests between different brands of transmitters doesn't really provide a lot of benefit. What is important, that your setup provides the minimum distance during range testing as indicated by your radio Mfg.

Why? Simple reason. That range test is conducted by reducing the transmitter power during the test. And, that reduced power level can be any value. That results in the mfg indicating a safe range test is around 30 paces for many transmitters.

But, it only takes a simple transmitter change to reduce the range test to 10 feet, 50 feet, or 500 feet for that matter. It all depends on the electronics selected by the mfg. So, the transmitter mfg could easily spec 30 paces for their range test, while putting out a range test signal good for 150 paces.

The bottom line, just range test your receiver and transmitter when brand new and make a note of it. Then, with a new receiver, range check it again and compare to the original receiver.
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