Looking for solutions on RF signal interference - FlyingGiants
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Old 06-02-2017, 12:35 AM
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Looking for solutions on RF signal interference

Ok this is the thing.

I've flown my Escapade before about 25 times very successfully with my VVRC 40 Twin with no RF signals interference at all, as we know the twins produce less vibrations than the single engines.

I decided that I will mount the twin on a H9 Beaver sometime this fall so, it came off the Escapade and into a box, my DLE 35 replaced the 40, the transplant went well.

I run the engine at home after it was mounted on the Escapade, all looked good, today I went to fly the Escapade for the first time, I have to confess, I didn't do a range check before the first flight, all was looking good, the TO was smooth then I pulled to a straight up line, on the way up the Escapade pulled over like if the flaps had deployed, I said WOW!! And reduced the rpms to idle and it behaved normal then I landed.

On the ground I run the engine, I noticed that at max rpms the ailerons were moving slowly up and down then one of the elevator servos was also moving on it's own but not the throttle ( digital )

So, first thing I'm doing is to put a hose clamp on the spark plug cup in case the RF signals are coming from a loose cup, I will test on the ground and if all looks good I will attempt to fly, if that doesn't change the problem then I will move to change the spinner for a better balanced one, if that doesn't work then I will have to look somewhere else.

Any thoughts?
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Old 06-02-2017, 12:46 AM
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check all of your servo extensions.. i bought a new unflown nieuport with a g26 on it and one aileron would start to deflect full throw and back to center slowly at half throttle and above.. i pulled it apart and found a poorly trimmed futaba plug pushed only halfway into a jr extension. a quick pass with the file and a shot of contact cleaner on all extensions and the problem went away. if you have a good plug lead that is on correctly, it is probably a bad extension vibrating and causing a problem.
also remember the servo connections we use are self cleaning only when plugged and unplugged so buried extensions that are never plugged and unplugged can develop corrosion and cauae similar issues to a half plugged in extension. when people balance the prop and the problem stops thats telling you they have a loose connection somewhere that they didnt find..
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Old 06-02-2017, 01:10 AM
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Thanks but I have no extension like that.

This Escapade was flying normally yesterday with the VVRC 40 Twin, the only thing new here is vibration at full rpms.

The hose.clamps I found at Kragens.
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Old 06-02-2017, 07:18 AM
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[QUOTE=CARS II;2650712]Ok this is the thing.

I've flown my Escapade before about 25 times very successfully with my VVRC 40 Twin with no RF signals interference at all, as we know the twins produce less vibrations than the single engines.

I decided that I will mount the twin on a H9 Beaver sometime this fall so, it came off the Escapade and into a box, my DLE 35 replaced the 40, the transplant went well.

I run the engine at home after it was mounted on the Escapade, all looked good, today I went to fly the Escapade for the first time, I have to confess, I didn't do a range check before the first flight, all was looking good, the TO was smooth then I pulled to a straight up line, on the way up the Escapade pulled over like if the flaps had deployed, I said WOW!! And reduced the rpms to idle and it behaved normal then I landed.

On the ground I run the engine, I noticed that at max rpms the ailerons were moving slowly up and down then one of the elevator servos was also moving on it's own but not the throttle ( digital )

So, first thing I'm doing is to put a hose clamp on the spark plug cup in case the RF
signals are coming from a loose cup, I will test on the ground and if all looks good I
will attempt to fly, if that doesn't change the problem the I will move to change the
spinner for a better balanced one, if that doesn't work then I will have to look
somewhere else.



I had this same thing happen and it ended up being a problem with the resistor inside the plug cap, put a new cap kit on it and all was good
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Old 06-02-2017, 07:52 AM
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It's unlikely what you're getting is actual RF, but it could be. True RF with 2.4 systems 'usually' affects the entire plane and not just one or two channels. It sounds like you're looking in the right places so far, but I'm curious about ignition battery placement, throttle servo placement, and so on.

Our servos are controlled by a pulse. The length of that pulse determines the servo's position. Any electrical signal that can make the servo 'see' a pulse will cause it to act up.
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Old 06-02-2017, 09:05 AM
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Hose clamp or not, make sure the plug cap is FULLY SEATED
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Old 06-02-2017, 10:21 AM
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considering everything else was good the day before the engine swap, id believe it to be the spark cap not seated all the way. I have had major glitches because of it. maybe remove from plane and test on a bench to rule out everything else. maybe change the plug incase the plug is cracked
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Old 06-02-2017, 11:49 AM
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Thank you all for your input.

I forgot to mention that the 35 came out of my GP Citabria that has also been flown successfully about 45 times with the 35.

So, both airplanes were flying just fine last weekend without any radio or engine problems, the only thing I did was to swap the 40 Twin for the 35 single, if I was to mount the engines back to the airplanes where they were mounted all will be back to normal, I think.

I understand that more details of the install would help but, I'm trying to keep it simple since as mentioned above the two airplanes where the engines came from were flying just fine, the only new thing here as I see it is vibration at max rpms.

I started with the simplest solution, I will run and maybe try to fly the Escapade on Sunday and will report back my findings.
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Old 06-02-2017, 11:57 AM
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n2182

My thoughts are around the same idea, I'm thinking the spark plug cup may be vibrating/loose at max rpms.

I will be thinking of what else may be for the next two days just in case the spark plug cup is not the part creating the problem.
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Old 06-02-2017, 12:02 PM
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BH

The cup is fully seated, I hope that can be seen on the pictures.
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Old 06-02-2017, 12:29 PM
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Put a small worm drive hose clamp around the base of the plug cap then you'll know it isn't loose.

Edit: sorry, had not read your first post where you already had a clamp on it.
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Old 06-02-2017, 04:41 PM
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Here is a link to my Escapade 30cc build thread, there you can see the install clearly.

https://www.rcgroups.com/forums/show...h-VVRC-40-twin
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Old 06-02-2017, 11:08 PM
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I have been reading at another thread on another forum.

The complain is that the digital rpm display unit doesn't work at max rpms and it resets constantly, he pushed on the spark plug cup and the symptom disappear.

My rpms display unit was doing the same thing at max rpms, that thread has giving me more to work with during the test run on Sunday. i will pay a close attention to the spark plug cup, even if the worm hose clamp fixes the problem I will remove the clamp and reinstall the spring and C clip to the cup and to the spark plug to recreate the symptoms, If I can do that I will be sure what part is creating the rf leak.

Thinking back at the field on Thursday when I run the engine on the ground to comfirm I had a problem the engine started acting crappy, like too rich but it was well tuned for the flight, on the third run it run just fine.

All this is leading me to think that the spark plug cup is getting loose or vibrating loose during the max rpms runs, Im hopping the clamp will solve that, I will be troubleshooting around the two spark plug contacts, positive and negative.
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Old 06-03-2017, 09:48 PM
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Interesting, still makes you wonder why there is EMI now verses before on the original airframe? Plug Cap/Spring/shielding... tweaks out at high rpm? maybe. would be nice to swap the Ign box with a buddies to see if that fixes it. I hate intermittent issues, hopefully you figure it out. Maybe double check that the dirty side isn't entangled with the clean side.
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Old 06-03-2017, 11:30 PM
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We will know tomorrow.
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