ED209

I recently modified a Sig 4-Star 40 for electric. It has a AstroFlight cobalt 40 geared, running off of 18 Ni-Cad cells with an APC 13-10 electric prop. It's a beauty and flies great, BUT I'm noticing to very scary interference problems that initially chalked up to pilot error (yeah... I'm a newbie). After a near-death experience on take-off today, I tried a range check with and without the motor running. With the motor disconnected, my Airtronics Vanguard radio and receiver passed with flying colors, But, when I tested at the same range with the motor running at half throttle, I found fluctuations in the speed controller and the ailerons went nuts. I have .01 mf capacitors running from the two motor leads to a ground on the motor cap. A guy at the field who used to race R/C cars suggested adding another capacitor between the two leads. I haven't tried this yet, but I'm open to suggestions. The receiver is installed approx. 10 inches behind the Jomar SM-4 speed controller and wiring, which I made as short as possible to avoid radio problems and keep the weight down.

Any suggestions?

Thanks in advance!

pmpjohn

Try the third cap or better yet a schotkey(sp) diode between the motor terminals. Twisting the power leads may help and make sure your rx ant wire is not routed near any other wiring.

John

Walt Thyng

My Feedback: (9)

You may get tow of these as I seem to have done somethng wrong in spell check.

Anyway, John is right you definitely need either a cap or a diode between the motors leads. Also check for dirty, chipped, worn or loose brushes. any of these can cause a problemFor you peace of mind I have flown an AF40G on eighteen cells with a Vangard many times with no problem.
Walt
Illinois

Walt Thyng

My Feedback: (9)

Oops, must be something about having my flight cancelled due to yesterday's storm in the northeast. I left out the ESC in my second attempt. I'm not familiar with Jomar, but some ESCs require a special diode on the motor leads. Check your instruction sheet.
Walt

LoveToFly-RCU

Hello ED209, I love your 4 Star 40, I had one of those on wet power for quite few years with different engines, even a 4 stroke, and after his DEAD, I got the idea to scratch build one as electric. I have a good collection of electric motors that I can use for it but I would like to use a brushless one. Consenting the interference that you have, beside the suggestions from the other friend, it is also good and very effective, to use what they call "RF chokes". These are very small coils that they look like small resistors and they should be 10uHenry of value. You need 3 of them, one for each lead that goes from the ESC to the receiver. You split the that wire and place it in serie up to the receiver: one for the signal wire, one for the positive and the other for the negative. This system has been suggested and proved by many modelers with interference like yours. I personally never had such problem and I'm using all type of ESC, receivers (small and big) and motors from small to big. I like also to fly high so the distance never was a problem. The capacitor across the two motor lead it is also a help and if you can put one of about .47uF ceramic type. it is worth to try. Also, Walt is right, some ESC do give more noise then others. Aldo.