Control interference from motor/ESC?

[Robert H]

I have a Bixler 2, with 35MHz Futaba. I have had quite a few flights without incident, but yesterday I nearly lost it!

Take off was normal, then it very soon became very difficult to control. My instructor took over & also had great difficulty controlling it. When we eventually retrieved the plane & did a range check (transmitter antenna retracted) all seemed normal with the motor off, but as soon as the motor was operated, all the controls went haywire, even at quite close range.

Could this be some sort of fault in the motor or ESC causing interference? If so which might be the more likely culprit? The motor is the standard HobbyKing item as is the ESC.

Any advice would be very welcome!

[fly boy3]

Hi Robert, I am no electric expert, but I have been told by club members on 35 MHz, that the Xc should be as far from the esc as possible. I,m ready to be shot down. Cheers

[Peter Jenkins]

I think you'll find this is not a fault but electrical noise generated by the motor and will need suppressors to eliminate as well as keeping the Rx and aerial as far from the ESC, motor and connecting wires as possible. In a Bixler, this might be difficult to achieve. I have read that one of the reasons for going to 2.4 GHz is that all the electrical noise stops at around 300 MHz so at 2.4 GHz all is peace and quiet! Since most electric models these days are on 2.4 GHz you don't tend to get the same stress on checking for electrical noise as there used to be with 35 MHz - and still needs to be! In any event, it is essential to check radio operation with the engine/motor running before your first flight. I'm slightly surprised that your instructor didn't check this out for you.

[Frank Skilbeck]

If it's a brushless motor then suppressors won't help, they were used to cancel the noise generated by the brushes on a brushed motor.

I did have one problem with a brushless 35mhz set up on an EDF with one one Rx which had a short aerial running alongside the fan, a change of Rx with a full length aerial provided a cure. So make sure the Rx aerial is kept as far away from the ESC and motor as possible, the MPX Easy Star has a tube running along the bottom of the fuselage for this purpose.

The other thing to check is that all the ESC-motor plugs are good, if not you can get some arcing and this will cause interference.

And yes 2.4 is much more immune that 35 mhz to electrical interference.

[Allan Bennett]

As a general rule you need to keep all high-power components (motor, ESC, battery, and their connections) away from the signal components (aerial, receiver, servos, and their connections) as far as possible. Sometimes wrapping the signal cable from ESC to receiver round a ferrite ring helps to reduce interference.

On all of my 35MHz models I used to use opto ESCs and separate NiMh receiver batteries to eliminate interference. That may not be practical with a Bixler, so maybe it's time to bite the bullet and go for 2.4GHz.

[Steve Hargreaves - Moderator]

Electric flight with 35MHz is a bit hit & miss.....I've had installations that have been perfect on 35MHz & never glitched & I've had them that are totally unflyable due to constant jittering of the servos. Very hard to pin down the actual reasons although it usually seems to be the higher kv motors that cause me grief.....you just have to accept that 35MHz & electric don't always get on.....

Strange that you have had a few good flights & now have a problem though......has anything changed? aerial rerouted? a different ESC maybe?

[Robert H]

Thanks for all your suggestion. I have been flying with this set up since February, never had this problem before and nothing has changed - hence my wondering about something having gone faulty. I will check all connections are sound, do some more range checks & try to relocate the ESC, but as Peter said, there is not a lot of room to move it. Everything was checked before take off & was fine.

[Stephen Jones]

Hi ,

A simple cure to try is to wrap the ESC and motor wires in tin foil to contain interference .

As i did above , and i have never had a problem since .

Steve

[Robert H]

Thanks, Steve, that is an easy thing to try.

[dan c 1]

I ran my bixler 2 for a year with 35mhz. Everything was just crammed in the little space. I never had any probs.The aerial was taped out along to the wing tip. Never had an issue. But I decided to put an frsky 2.4 module in my 35 mhz tx and an frsky RX in the bix plane. Was pretty cheap to do if you have nice tx you want to keep. If youre handy with a soldering iron.just a thought. Saves buying a whole new tx

[dan c 1]

http://www.hobbyking.co.uk/hobbyking/store/__17205__FrSky_DHT_8ch_DIY_Telemetry_Compatible_Transmitter_Module.html