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Waterproofing/Protecting Horizon electronics

Hi there!

First time poster, and this has probably been asked before and if so, I apologize for the duplicate thread, but I I wondered what was best to use to protect the integrated receiver/ESC/Servo boards that are found in Horizon ultra-micro planes. They often have the elevator and rudder servos built onto the board so the heatshrink and epoxy option is out.

I don't plan to turn any of them into submarines any time soon but I would like to be able to fly in rain and crumby weather without a fear of shorting out. After watching Peter's video on the subject I'm leaning towards a coat of the HD CorrosionX. Is my thinking right, or would using the regular (or Aviation?) formula be better for this odd mish-mash?

Thanks to anyone knowledgable about this!


Legendary member
I’m not sure this a good idea. The spray could lock up the servos.
+1 ☝️

those exposed linear servos wouldn't like that.

Really not a lot you can do with the micros that use linear servos in my experience. That being said I've rarely had a problem with them. The worst I had was when I turtled my UMX timber on a pond. No damage though, just took a little drying off... you can see it on video here:


Elite member
You can’t fly in torrential rain. Most rain comes with wind and the micros get blasted all over the sky.
The linear servos as noted above won’t take conformal coating, which is used to weather proof flight controllers.
My Sport Cub is fine in light misty rain, it’s also survived a couple of weeks outside in UK weather when it got lost. The boards on those planes are pretty well buried. If it’s rainy enough to get that wet then your transmitter is going to get soaked, it’s likely to be windy and in that weather it’s building time not flying time!
If the linear servos get damp they can get twitchy, with fluttering movement at idle. You can fix that with a light spray of electrical contact cleaner. Aside from that I wouldn’t put anything on them.


Build cheap, crash cheap
From what I've seen on my Nano CPX, micro linear servos use carbon element linear slide potentiometers for position feedback, similar to those used in audio applications. I have used CorrosionX and commercially available lithium grease in carbon linear rotary (how's that for a contradictory sounding name) potentiometers (throttle position sensors) to no ill effect in precision or range. CorrosionX should be fine to use on a micro linear servo, as that's the only electronic component in them with potential to respond questionably to it. Just be careful with overspray because it may interfere with adhesives, maybe spray it into a little cup and use a syringe and needle to put it where it needs to go.
Sorry, it might have helped if I had linked to the guide I was using as a reference. It's here:

Specifically the reference to Corrosion X HD being good for servos but regular Corrosion X being good an acceptable protection for receivers and kind of ok for ESCs.

@varg Based on that and what you've said I think I'm pretty settled on just spraying a bit of regular CorrosionX on the combo boards and servos. Should be plenty to protect them from stray drops that get blown under the wing or into the cowl. Or the occasional botched water landing.

@FDS Naturally if it's blasting down I'm going to be inside with a hot drink but I do want to be able to fly confidently in what I'd call "English weather". Gray, a breeze, and mild rain. I'd keep an old jacket across my transmitter to keep it dry, or just fly from some shelter. A little cloth shouldn't bother the signal any.

Thanks for the input everyone!