I mentioned this before & now it comes in a can and it's actually for sale. Check it out. http://junkee.com/someone-invented-magic-and-it-is-freaking-us-out/14880
Ahh -- after reading the reviews it looks like once you touch the top coating it rubs off easily. Darn! But really cool!
I still believe the solution to the moisture risk we have is some kind of cover, with the option of providing some degree of active cooling for our beleaguered and overworked ESCs. I wish I had access to a 3D printer, and I'd give it a rip. We have 8 25mm booms that it could clip to (or attach to with velcro or something). As for fans, I'd put two fans in it: one in the 'front' of the copter (boom 1) blowing towards boom 5, and the second at the 'rear' of the copter blowing rearward, too. That would create an airflow similar to what you get during ordinary flight. And I doubt the accumulated 'thrust' would effect the balance of the copter, but if it did, you could probably re-balance it a bit to make it slightly nose-heavy. Hmm...but I just realized that the fan solution runs the risk of blowing moisture through the hub. I guess you'd need some kind of baffling to trap some of the moisture, right? Where's one of those engineering types when you need them? Shaun? Andy? It'd be great if somebody published a 3D model of a cover that others could use to print their own. And with little fans being just a few dollars, I bet the whole thing could be done for less than $10US in materials.
The double fan idea is not a bad one -- and I wouldn't worry too much about the moisture if you've put a layer of conformal silicon spray on. The heat of the BL-Ctris will evaporate the moisture. As to 3D printing, watch out -- it's not the magic solution to the problem. There's a lot of hype about it, but the technology is in its infancy....you need to wait for it to move into its adultery....oh. Bad choice of words, eh? Andy.
The reason I thought of 3D printing for this application is that this type of thing isn't under severe duress, so it doesn't have to be super strong. If it breaks or blows off...NBD. I wouldn't rely on 3D printed components for critical airframe bits...at least not as I understand it.
The question I would have and would test fist is if this stuff is conductive. That could be an issue. On the dome thing. I have contemplated doing cheapest thing possible and that is using a stainless steel salad bowel with a vent hole and a fan to pull the heat out. One of the things I noticed is that OAT plays obviously a huge part in the BL temps. I also notice that the sun radiating on the BL's seem to be more of a contributor unless there is some air cooling the BL's. I don't think a fan will contribute enough thrust to do anything to the system stability. The only issue with a fan maybe adding electrical interference to the compass and video TX possibly. A bright silver bowel will reflect the sun away from the electronics. I have even contemplated making a sunshade disc out of car window shade material that would be over the BL's but allow more venting. There does seem to be some reasonable options. Honestly I think at the end of the day having the new FC the FF is doing with separete ESC'S That are not integrated on a single Power Distribution board will be the answer. As much as like the MK avionics these BL'S are not designed for robustness for heavy load applications. I think putting separate ESC's on the top of the booms near the motors will be an ideal solution to ensure cooling in extreme temp environments.
Don't think it is conductive since one of the videos shows them popping apart and iPhone, doing the coating, and then dunking it in water. The only thing missing was them trying to talk underwater.
There's a difference between sealing surface mount electronics that don't radiate heat and trying to seal the MOSFET's. If you seal the MOSFETS you are asking for trouble which is why Andy tapes them up in his modifications. IF you tape the MOSFETS and expose them to water (not necessarily a little moisture) they definitely will fail. Too risky if you ask me. IF you put extra fans and a cover on the top your probably going to be adding at least 200-300 grams at least which probably isn't the best thing if you already fly a 5D MKIII with the MK electronics. We have 3D printers at the school I work for. They have been there for over 15 years I would say they work very well. If you draw it up I will print it for you Steve.