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R7008sb signal loss (interference ???)

Old 07-17-2020, 04:11 AM
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marsubilami
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Default R7008sb signal loss (interference ???)

Hello everyone

I had a weird experience last week when flying my 35cc gas plane (Texan 2) with my 14SG and R7008sb.

I had 2 flights that day. The first flight, with no one flew their plane, everything was alright.

On the second flight, where there were also some people flew their planes, they used Frsky Tx (900mhz).

After my plane took off, it started to flew “weird” (glitched), uncontrollable for 2-3 seconds and recovered afterwards. I decided then to take a last turn to make a landing, during the turn, the plane started over to act like previous error, even though it recovered and I managed to land it.

I used 2 life batteries 2S 1450 mah.

Anyone know what is going on? Or maybe has the same experience.

thanks
Old 07-17-2020, 07:09 AM
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FUTABA-RC
 
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FIrst off, tell me what you mean by "glitched". Did you get un-commanded surface movement or did it just stop responding?

Second - at any time was the TX antenna pointing (the tip) directly at your plane? There is a dead spot of the tip of all 2.4 antennas and you need to be careful of that.

Third, do you have a failsafe set? Low throttle on signal loss will act to be diagnostic of signal loss.

Also, is this a new plane or does it have many flights on it?

Give me a bit more info, and maybe we can get this sorted out.
Old 07-17-2020, 05:48 PM
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marsubilami
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Ok, let me try to answer your questions:


1. Did you get un-commanded surface movement or did it just stop responding? un-commanded surface movement

2. at any time was the TX antenna pointing (the tip) directly at your plane? The antenna is pointing to my right hand or to 3 o'clock direction

3. do you have a failsafe set? Low throttle on signal loss will act to be diagnostic of signal loss. Yes, I set the failsafe: the lowest level of the throttle

4. is this a new plane or does it have many flights on it? Yes, it is a new plane with 3 total flights. The error happened on the 3rd flight.
Texan 2 plane from ESM.
Composite-made fuselage and balsa-made wing.

Other information:
The receiver antennas placed outside with one antenna pointing horizontal, the other antenna pointing vertically or like a “L” letter.

The receiver is next to the 2 ea Life batteries, but far away from CDI and Ubec.


Last edited by marsubilami; 07-17-2020 at 06:29 PM.
Old 07-17-2020, 07:37 PM
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OK, so no failsafe event, but an un-commanded input. That is almost always due to some internal noise. double check all the connections are snug, etc. Things like a loose plug cap, etc. can be an issue.

Are using S.Bus?
Old 07-17-2020, 09:46 PM
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Originally Posted by FUTABA-RC View Post
OK, so no failsafe event, but an un-commanded input. That is almost always due to some internal noise. double check all the connections are snug, etc. Things like a loose plug cap, etc. can be an issue.

Are using S.Bus?
No, I am not using sbus.
One that I confused is when I flew my plane alone, nothing happened, normal. But when there were 3-4 people playing planes, the trouble happened.
Old 07-17-2020, 10:17 PM
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That would have resulted in external interference which would have caused a failsafe event, not erratic control inputs.
Old 07-17-2020, 10:44 PM
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marsubilami
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Ok.

How if I wrap the receiver with aluminium foil to avoid any interference?

And if I rebind the Rx and Tx prior to fly my plane, especially when others are turning ON their Tx, will that effect much to avoid the error?
Old 07-18-2020, 06:37 AM
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Originally Posted by marsubilami View Post
Ok.

How if I wrap the receiver with aluminium foil to avoid any interference?

And if I rebind the Rx and Tx prior to fly my plane, especially when others are turning ON their Tx, will that effect much to avoid the error?
Again, the other radios were not the issue. You have some sort of internal noise as the most likely culprit. Rather than wrapping the RX in anything, I would look for the core reason. Plug cap, bad connections, etc. Even a servo acting up can cause an issue like this. You have something causing it. Fix that.
Old 07-19-2020, 06:21 AM
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Originally Posted by FUTABA-RC View Post
Again, the other radios were not the issue. You have some sort of internal noise as the most likely culprit. Rather than wrapping the RX in anything, I would look for the core reason. Plug cap, bad connections, etc. Even a servo acting up can cause an issue like this. You have something causing it. Fix that.
Everything is fine inside the kit. Very tidy and well-arranged. The first and second flight were fine.

One of friend had also a similar experience, he used T8FG.
The funny thing is, there are no similar experience happened to those who use Frsky, JR or Spektrum transmitter.
Old 07-19-2020, 07:20 AM
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Not sure what to tell you. I gave you a suggestion on what to check. If your were getting outside interference from other radios (extremely unlikely on 2.4GHz) then you would get a failsafe event. If surfaces are moving on their own that is almost certainly an internally generated issue.
Old 07-19-2020, 08:00 AM
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I'll add that I fly glider contests where there can be 10+ other planes in the air with the pilots all located fairly close to each other. I cannot recall every hearing a report similar to your situation.
Old 07-19-2020, 04:49 PM
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OK, noted. So it is 100% probability comes from internal parts and connections, isn't it?
I will double check all of the components inside the fuselage as well as the wing, servos, cables, UBEC for ignition, plug cap, etc.

What is the most contributing factor in regards of internal issue that would make noise or interfere the R7008SB?

I have an elevator servo located at the end of the fuselage or near the horizontal stabilizer, so it requires a long cable. Is it an issue or should I use a booster extension cable?
Old 07-19-2020, 04:55 PM
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Ignition, servo going bad, loose plug cap, broken/frayed plug wires, etc.
Old 07-21-2020, 04:14 AM
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If you are running a DLE engine or similar ignition. Make sure the spring is in the spark plug cap and that it is tight. I have scene this cause all sorts of issues. A lot of guys leave those springs out or they are not snug in the cap.
Old 07-21-2020, 05:34 AM
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Originally Posted by ifly3d View Post
If you are running a DLE engine or similar ignition. Make sure the spring is in the spark plug cap and that it is tight. I have scene this cause all sorts of issues. A lot of guys leave those springs out or they are not snug in the cap.
Thank you.
Take the spring out might be great idea.
I also make another ground cable that connect the spark cable and the engine mount to help reduce the noise (hopefully).
Old 07-21-2020, 05:38 AM
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Originally Posted by marsubilami View Post
Thank you.
Take the spring out might be great idea.
I also make another ground cable that connect the spark cable and the engine mount to help reduce the noise (hopefully).

Sorry, I did not mean to leave the spring out. Make sure its in the cap. What I meant is guys will not put it in the cap and have issues as well. Sorry for the confusion.
Old 07-21-2020, 06:28 AM
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Good suggestion and one of the items I noted. Please keep in mind this is not an open discussion forum. Thanks
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Old 07-21-2020, 03:49 PM
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marsubilami
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Thanks Josh & Bill. Appreciate your help!
Old 05-18-2022, 02:00 PM
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Originally Posted by FUTABA-RC View Post
Ignition, servo going bad, loose plug cap, broken/frayed plug wires, etc.
borrowing, and want to ask, my spark wire has been close and sometimes on the header pipe. it sits in the open and get prop thrust as cooling on that part.
is there likely to melt the silicone / plastic covering on the spark cables within the metall armored sock that is running outside the spark wires?

my self had a crash due to strange RX inputs today, and think i might be due to just 10min before i lost the spring that goes in to the spark-plug cap.. but reading what you have been writing i started to think if i might have damaged wires from the ignition box also.

Best Regards.
Old 05-18-2022, 03:45 PM
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Uncommanded movement of a surface is almost always the result of some internal interference like frayed wires, metal on meta, etc.
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Old 05-18-2022, 04:45 PM
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Originally Posted by FUTABA-RC View Post
Uncommanded movement of a surface is almost always the result of some internal interference like frayed wires, metal on meta, etc.
Ok, so new ignition then. It ran good tho.
Old 05-19-2022, 01:16 AM
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Originally Posted by FUTABA-RC View Post
Uncommanded movement of a surface is almost always the result of some internal interference like frayed wires, metal on meta, etc.
cuz, i have looked in to all cables. everyone looks good. the only cable i cannot confirm is the spark-cable that is within its own metall shielding. tho i thought that was a good protection. but now i have learned it might not be.

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