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Silicon conformal coating for float plane electronics.


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I've never found it really necessary. Make sure the joint between the wing and fuselage is sealed with a bead of silicon sealant and that will keep most water out. The He5 is a very stable layout for water handling so you are unlikely to turn turtle and get things wet. Just consider how any spray thrown up by the prop can be kept out of the ESC and preferably the motor too.

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Likewise, I’ve never bothered sealing the electronics. The trouble is with any sealing job, if you do a 99.9% perfect job, in the event that it does get submerged, the water will find that 0.1% gap and then it will take forever to dry out.

Servos, motors and even receivers will generally survive a brief dunking (unless you’re operating off salt water). ESCs often survive but not always, so if you can position the ESC such that it would remain above the waterline if the model does turn turtle, you’ll be fine.

Trevor

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Thanks for your replies everyone. In the end I decided to use West System Epoxy which I use for many other things and have tons in stock. I mixed 12 grams into a small pot and warmed slightly to make it very thin. Removed the heat sink then dipped the complete esc into the epoxy. Made certain everthing was saturated then suspended the esc and left to drain. Replaced heat sink after half an hour and now three hours later I have an esc completely water tight. Will test tomorrow under water.

p1070378.jpg

Edited By Michael Barclay on 17/05/2020 15:05:14

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YMMV but personally potting in epoxy is the last thing I'd have done to an ESC. I'd be concerned about the ability of the MOSFETs to be able to transfer heat to the heatsink. That may well cause you more reliability problems than the possibility of getting water in the ESC.

I've only ever seen a couple of people pop their ESCs on water planes after turning the model over on the water and in both cases they kept trying to apply power to the motor with the model submerged. Could be a coincidence but perhaps not?

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Posted by Alan Gorham_ on 17/05/2020 15:11:17:

YMMV but personally potting in epoxy is the last thing I'd have done to an ESC. I'd be concerned about the ability of the MOSFETs to be able to transfer heat to the heatsink. That may well cause you more reliability problems than the possibility of getting water in the ESC.

I've only ever seen a couple of people pop their ESCs on water planes after turning the model over on the water and in both cases they kept trying to apply power to the motor with the model submerged. Could be a coincidence but perhaps not?

Hello Alan. I made certain there is no epoxy between the heatsink and the MOSFETs. Mike.

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Well it can't be sealed then? I honestly think for a low wing floatplane such as the He5 you will only get water in the electronics if you put it nose first into the water (ie crash). I've been flying waterplanes for over 30 years and have not really found this necessary. I might consider it on high wing model such as a Cub because they will tip over with little provocation.

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Posted by Alan Gorham_ on 17/05/2020 15:27:29:

Well it can't be sealed then? I honestly think for a low wing floatplane such as the He5 you will only get water in the electronics if you put it nose first into the water (ie crash). I've been flying waterplanes for over 30 years and have not really found this necessary. I might consider it on high wing model such as a Cub because they will tip over with little provocation.

I am not disputing your experience Alan but I am a person who is not afraid to think through a problem and try something new. I spent a lifetime doing this in my work and it is the only way that the human race has made progress. I will test the esc later this week and report on here whether the system is a success or a failure. Mike.

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What I have done on several sea planes is to build an open box attached to the underside of the wing on the centre line so that it sits inside the fuselage. The Rx, UBEC and Speed controllers are then mounted inside the box. That way when you end up inverted in the water and the wing semi submerged the box becomes upright keeping the Rx dry. Have motored out several planes back to the bank in an inverted condition with this set up so it does work. Motors get very wet though so a liberal amount of WD40 helps to dry things out.

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I said I would report on here after testing the epoxy waterproofing of my esc. and I can say the system I used is an unmitigated success. I first tested the esc underwater for a period of 5 minutes and it worked perfectly. I then ran the motor using an oversize prop to generate heat in the esc and the heat was transferred to the heat sink as normal. The bond between esc and heat sink was unaffected by the heat, and the esc is now installed in the model. My esc is fitted under the battery compartment with the heat sink exposed and is not in a watertight compartment.
I should perhaps enlarge on my original description of epoxy encapsulating the esc. in case others wish to try the system.
1.... It is neccessary to level the FETs to ensure good contact with the heat sink as they will not be level as installed.
2....I used West epoxy which is quite thin. Quick curing systems being thicker may not conduct heat to the heat sink from the FETs effectively.
 

Edited By Michael Barclay on 23/05/2020 13:00:09

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