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Jun 06, 2020, 05:56 PM
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Help!

Jeti DS-16 Signal Loss - Crash


Hey guys,

Issue:
I was flying my EFYAK54-88 (20 flights on it with current setup, 2nd of the day) today and 3min 15sec into the flight during a humpty dumpty I lost all control, it flew around in a circle for about 15 seconds then lost altitude and hit the ground completely destroying the plane.

Troubleshooting:
As soon as I lost control the tx started calling out "signal loss" and I moved toward the plane but no success. I left the tx on until I recovered the plane and it never regained signal. It was flying it about 100 yards away. Once I got to the plane I immediately checked the batteries (2 installed for redundancy) and they were both at 50%. Got back to the pit and the receiver bound just fine and passed range check. I removed/tested each servo and switch... no issues there. Couple of the guys suggested there could be a short somewhere in the circuitry but I confirmed there was none.

Could there be something wrong with the transmitter or receiver?
Is there any other troubleshooting I can do on my end?

TX: DS-16
Receiver: R7Plus

I have attached the log from todays flight (crash at 3:15).

Thanks for the help
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Jun 06, 2020, 06:38 PM
Registered User
Quote:
Originally Posted by bc1960
Hey guys,

Issue:
I was flying my EFYAK54-88 (20 flights on it with current setup, 2nd of the day) today and 3min 15sec into the flight during a humpty dumpty I lost all control, it flew around in a circle for about 15 seconds then lost altitude and hit the ground completely destroying the plane.

Troubleshooting:
As soon as I lost control the tx started calling out "signal loss" and I moved toward the plane but no success. I left the tx on until I recovered the plane and it never regained signal. It was flying it about 100 yards away. Once I got to the plane I immediately checked the batteries (2 installed for redundancy) and they were both at 50%. Got back to the pit and the receiver bound just fine and passed range check. I removed/tested each servo and switch... no issues there. Couple of the guys suggested there could be a short somewhere in the circuitry but I confirmed there was none.

Could there be something wrong with the transmitter or receiver?
Is there any other troubleshooting I can do on my end?

TX: DS-16
Receiver: R7Plus

I have attached the log from todays flight (crash at 3:15).

Thanks for the help
Assuming you had a throttle fail safe set, it looks like it simply switched off in the middle of the flight.

1) You didn't say what the throttle did so I'm assuming nothing ? If it was programmed to go to idle on loss of signal but didn't, that a strong indicator of power failure.

2)What were you using for switches, # of battery connections, etc ? Based on the voltage drops, though not the cause of the crash it looks like you could use heavier wiring, better switches of better batteries. Since you said this was the second flight the packs SHOULD have been better than 80% capacity assuming 2, 2200mahish packs..

3)You said you left the transmitter on until you recovered the plane but never regained control.
So standing right over the plane nothing worked ?
Was it still powered on ?
Did you try manually moving a control surface / servo to see if they appeared to be powered ?

4)Did you power cycle airplane and then everything worked ?

5)You said the batteries were @50% but since they appear to have been LiFE/A123 batteries, how did you determine that ? Check with a meter (not terribly accurate) or recharge the pack and see how much it took to recharge ?
Jun 06, 2020, 07:09 PM
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Thread OP
Quote:
Originally Posted by wfield0455
Assuming you had a throttle fail safe set, it looks like it simply switched off in the middle of the flight.

1) You didn't say what the throttle did so I'm assuming nothing ? If it was programmed to go to idle on loss of signal but didn't, that a strong indicator of power failure.
First, I did not have fail safe set. Second, it appeared that the throttle stayed where it was when signal was lost, which was about 3/4 stick.

Quote:
Originally Posted by wfield0455
2)What were you using for switches,
The switches were bought with the plane so not sure exactly what they are.

Quote:
Originally Posted by wfield0455
# of battery connections, etc ?
battery to switch to extension to receiver (x2)


Quote:
Originally Posted by wfield0455
3)You said you left the transmitter on until you recovered the plane but never regained control.
So standing right over the plane nothing worked ?
Was it still powered on ?
Did you try manually moving a control surface / servo to see if they appeared to be powered ?
I did not try moving sticks while over the plane, just unplugged batteries (wasn't thinking) not sure if the plane was powered.

Quote:
Originally Posted by wfield0455
4)Did you power cycle airplane and then everything worked ?
The plane was pieces but yes, the receiver bound as it should on power cycle & passed range test. Have since checked that all servos are working. The 2 switches are functioning correctly as well.

Quote:
Originally Posted by wfield0455
5)You said the batteries were @50% but since they appear to have been LiFE/A123 batteries, how did you determine that ? Check with a meter (not terribly accurate) or recharge the pack and see how much it took to recharge ?
They were LiFE2100s, checked with a cheap tester.

Thank you
Jun 06, 2020, 08:23 PM
Registered User
Quote:
Originally Posted by bc1960
First, I did not have fail safe set. Second, it appeared that the throttle stayed where it was when signal was lost, which was about 3/4 stick.


The switches were bought with the plane so not sure exactly what they are.


battery to switch to extension to receiver (x2)



I did not try moving sticks while over the plane, just unplugged batteries (wasn't thinking) not sure if the plane was powered.


The plane was pieces but yes, the receiver bound as it should on power cycle & passed range test. Have since checked that all servos are working. The 2 switches are functioning correctly as well.




They were LiFE2100s, checked with a cheap tester.

Thank you
Not sure how much more we can tell from this since you didn't have fail-safe set. If it was set to idle or stop we'd know what happened based on the throttle behavior but we don't have that info. Also, since you didn't check to see if anything was working or still powered when you got to the plane so no further info there either.Without this sort of information its hard to tell anything more but it's really hard to remember to check all this stuff when something bad happens..

In spite of the fact that you had 2 of them the switches and associated wiring is my best guess as to the cause of the problem.
Jun 06, 2020, 09:10 PM
Registered User
Thread OP
Quote:
Originally Posted by wfield0455
Not sure how much more we can tell from this since you didn't have fail-safe set. If it was set to idle or stop we'd know what happened based on the throttle behavior but we don't have that info. Also, since you didn't check to see if anything was working or still powered when you got to the plane so no further info there either.Without this sort of information its hard to tell anything more but it's really hard to remember to check all this stuff when something bad happens..

In spite of the fact that you had 2 of them the switches and associated wiring is my best guess as to the cause of the problem.
Thank you for the help. I am just concerned about using my transmitter and/or receiver again... if I figure anything else out will update here.
Jun 07, 2020, 08:36 AM
Registered User
Thread OP

New Info


Alright new info I found out but not sure if it helps.

1) The failsafe was enabled. All pins were set to "Hold". I did not set it this way/never realized it was on.

2) I charged the batteries to full. Bat 1 took 76 mAh/3min56sec to charge to full. Bat 2 took 92mAh/4min26sec to charge to full (icharger308duo)

Thanks
Jun 07, 2020, 10:23 AM
Registered User
Quote:
Originally Posted by bc1960
Alright new info I found out but not sure if it helps.

1) The failsafe was enabled. All pins were set to "Hold". I did not set it this way/never realized it was on.

2) I charged the batteries to full. Bat 1 took 76 mAh/3min56sec to charge to full. Bat 2 took 92mAh/4min26sec to charge to full (icharger308duo)

Thanks
By default all Jeti receivers have fail-safe enabled with all servos set to Hold so this really doesn't tell us anything more. If the throttle channel fail-safe had been set to idle or stop and that didn't happen then we would be 100% certain you had a power failure as the only way a properly configured fail-safe wouldn't close the throttle is if there was no power to move the servo.

Assuming this is a gas airplane if you had the ignition powered by a device such as the TechAero IBEC which is powered by the receiver, a power failure would also have shut the engine down since there would be no receiver power to keep the ignition going. Assuming a gas engine, how was your ignition powered ?

There was never really any question about the batteries causing this as the receiver voltage telemetry showed you had 6.6V to the receiver immediately before everything shut down.
Jun 07, 2020, 12:47 PM
Registered User
Thread OP
Quote:
Originally Posted by wfield0455
By default all Jeti receivers have fail-safe enabled with all servos set to Hold so this really doesn't tell us anything more. If the throttle channel fail-safe had been set to idle or stop and that didn't happen then we would be 100% certain you had a power failure as the only way a properly configured fail-safe wouldn't close the throttle is if there was no power to move the servo.

Assuming this is a gas airplane if you had the ignition powered by a device such as the TechAero IBEC which is powered by the receiver, a power failure would also have shut the engine down since there would be no receiver power to keep the ignition going. Assuming a gas engine, how was your ignition powered ?

There was never really any question about the batteries causing this as the receiver voltage telemetry showed you had 6.6V to the receiver immediately before everything shut down.
Thanks for the info. My ignition did not have a kill hooked to the receiver, only a switch. It is a DA50.
Jun 07, 2020, 01:26 PM
Registered User
Quote:
Originally Posted by bc1960
Thanks for the info. My ignition did not have a kill hooked to the receiver, only a switch. It is a DA50.
At this point it's unlikely you'll ever fully understand exactly what happens but Id' suggest looking at it as a learning experience and trying to think about what you could do differently to avoid finding yourself in this situation ever again. Things like always setting up throttle fail-safe, perhaps using something like a Tech Aero IBEC to power your ignition and eliminating the ignition switch, add Rx Signal Quality (Q) to your logging instead of antenna signal strength (at least add Q in addition to antenna). Stuff like that.. Now that it's fresh in your mind, think about pieces of information you wish you had and try to think of a way that you will have that info should problems arise in the future.. The surprising thing is that once you start looking at things this way, you almost never have these sorts of problems anymore..

Unless the case got crunched in the crash I rather doubt there is anything wrong with your R7 and I'm sure your transmitter is fine too. About all you can do at this point is test everything the best you can and perhaps test fly the R7 in a foamie of something and hope for the best...
Jun 07, 2020, 08:23 PM
Registered User
Thread OP
I have discharged and charged both batteries this evening.
Battery 1 put back in 2080ma.
Battery 2 put back in 2114ma.
These are 2100mah batteries.

Does this mean the batteries are ok?
Jun 20, 2020, 05:50 PM
Registered User
Thread OP

Update


I have sent the receiver to Esprit for a good range test.

I have purchased a barely used Extreme Flight 85 inch Extra 300 EXP. My plan is to use 2 lipo batteries for receiver. Still unsure of what size batteries. I have a Jeti DSM 10 that i`m considering installing. That will give me battery redundancy but only one switch. I have ordered a Tech Aero IBEC, but unsure whether to use it or not. I do like the idea of not having the third battery though.

Another concern is the antenna setup with all the carbon fiber in the fuselage.

Any thoughts on this setup?

Thanks, Bill
Jun 28, 2020, 02:06 PM
Registered User
Sorry to hear of your incident. The actual antenna portion must be external and also not in contact with carbon fuse. Showing REX-7 receiver on F5J type sailplane. Note, the actual antenna is the last 2" or so of the 6" long whiskers, typically a different color sheath tube. If I were to tape one of the antennas to fuse, I could see a reduction in reception on the logs. If the antennas are inside the CF fuse its a recipe for signal loss regardless of the radio brand. This model could be 400m up and 2000m away with very strong signal strength.

Actually this is an old picture. Someone pointed out antenna exit its not optimal because the wings are carbon skinned so there is potential for blanking at certain flight attitudes so they have since been moved forward. Basically you want them as visible as possible from all flight attitudes.

Now if you have power issues or interference issues that's a different matter, but since you mentioned carbon.
Jun 28, 2020, 05:00 PM
Registered User
Thread OP
Quote:
Originally Posted by ptxman
Sorry to hear of your incident. The actual antenna portion must be external and also not in contact with carbon fuse. Showing REX-7 receiver on F5J type sailplane. Note, the actual antenna is the last 2" or so of the 6" long whiskers, typically a different color sheath tube. If I were to tape one of the antennas to fuse, I could see a reduction in reception on the logs. If the antennas are inside the CF fuse its a recipe for signal loss regardless of the radio brand. This model could be 400m up and 2000m away with very strong signal strength.

Actually this is an old picture. Someone pointed out antenna exit its not optimal because the wings are carbon skinned so there is potential for blanking at certain flight attitudes so they have since been moved forward. Basically you want them as visible as possible from all flight attitudes.

Now if you have power issues or interference issues that's a different matter, but since you mentioned carbon.
Thanks for replying. The plane that went down only had a carbon wing tube. The plane Im about to start setting up has the carbon formers.
Jun 28, 2020, 06:11 PM
Registered User
Neither of those CF components would present a problem at all. Just avoid routing antenna in proximity just to be safe. I agree with post #9, set up signal quality (Q) logging & alarm. Its there to utilize. Hopefully you will discover some non-radio related issue as the culprit which, from my experience, is usually the culprit.
Jun 30, 2020, 07:22 AM
In search of speed......
Dansy's Avatar
Putting the antenna outside...is a glider thing yes I have 2 of them and the antenna are outside.

In my jets/Gas and electric plane....and most have some carbon to a lots of it, placement of the antenna is critical, also need to be away from anything that can generate interference....

What I don’t get from your crash, is to get the lost signal and lose control at the same time, would to me indicate 2 possible problems.

1- you lost power
2-the RX burned up

On the Jeti Duplex RX (pretty much all of them) you have 2 antenna’s, the RX used one for telemetry and one for control......the best one will be the control, the first one you will loose is always telemetry and control last.....to loose both antennas at the same time....mean some type of complete failure.


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