Hi guys,
I was asked to come film in avoriaz, france to film for the volcom rail jam, video above.
I have flown in snow storms and temperatures down to minus 10 with no problems, but i discovered on this day is the dangers of "freezing fog". You can see from the video that it was only snowing a little, wind was gentle and it was a positively warm 5 degrees. I thought this was going to be a good day to get the most out of my hexa and show people what we can achieve using a drone.
However, on my first flight after just a couple of minuets i was in real trouble. I was at full power and coming down. Luckily i was near my landing zone and i managed to make a hard controlled landing. Normally i can fly for 20 mins no problem so was a little perplexed at my loss of power.
A quick inspection revealed the problem. A thick layer of ice on the underside of the props. My drone hovers at about 60 percent throttle, but with just a millimetre of ice on the bottom of each prop i can't even take-off! In hindsight it was an obvious danger, but be warned the dangers of freezing fog.
Unfortunately the weather got worse and my first flight was the only shot used in the video edit, they used as their intro. I was disappointed but the clients were happy,and impressed that i flew at all in the conditions. I have been asked to com and do the tour next winter perhaps!
What i need now is a solution to freezing props. I know that real choppers use heated blades, but i can't see that being available to us for a while. I think if i had a heated cabin and 2 hexa's flying in rotation with pre heated props that it might be possible. If anyone's got any ideas i'll happily test them....
Thanks tristan
Comments
I think a Tradheli might work in these conditions. I flew my little 450 guy in freezing fog once. I came down and noticed the blades were completely coated in ice and I hardly noticed. I stopped flying, but I could have cleaned it off and flown again. A bigger heli like a 600 would do even better I bet.
It's not an ideal situation, but for short flights, I think it would work.
I don't think RainX would work. If I understand properly, RainX is actually a water attractant. It increases the surface tension, which makes it form a taller bubble, which allows the wind to blow it off easier. I believe that's sort of how it works?
And my experience with using RainX on cars in this type of weather, yeah, it seems like they get MORE ice buildup.
You might try dipping the props in Rain-X (might help in preventing ice buildup.)
or better yet, one of the several new nano coatings folks are working on for that.
one example Anti-Icing Superhydrophobic Coatings
I'm not sure how well any solution will work for freezing fog or any sort of icing condition. Even full size helicopters and aircraft will try their best to stay out of freezing fog. I know I try and avoid it like the plague, even though the plane I fly is certified for icing and holds the ice very well. I think the trick in all corners of aviation, from UAVs to full size is knowing when to stay on the ground. Just my 2 pennies.
The wear is most likely the main reason why it's not used in commercial aviation. That and the complexity of applying the coating and the fact that it can't just be painted on like regular paint, but require an extensive procedure (usally needs to be done by specialized shops). But at the scale of a RC prop the wear is much less, and the cost makes it possible to have dedicated propellers just for when flying in cold weather.
Here is one shop offering such services. https://www.liquipel.com/shop/
John Birkeland: Do you have a link, or some sort of other information about this special anti-ice paint? Every commercial aviation de-icing system I've heard of involves electric heaters, use of bleed-air off a turbine engine, or direct application of alcohol or glycol antifreeze solutions via sprayers or weeping wing setups.
I am aware of ultra hydrophobic coatings, but they wear off with use and I'm not aware of then being used commercially in the aviation industry as anti-ice coatings.
This is a well known problem in aviation. The water particles are very small, meaning that they freezing instantly the moment they hit the propeller. And then the ice builds layer by layer until the propeller becomes useless. The coating should stick without any problem, it's like a very thin layer of paint. Only problem I can think of is that propeller vibrations could lead to cracks in the coating.
So does that antiicing stuff stick on the propeller even though the propeller spins at a rather high speed.
Actually I am a bit baffled that the water sticks in the first place. Should the centrifugal force carry it away before it could freeze?
I think there is some misconception to how the badly named "anti-icing" solution works. It's not some alcohol based solution to prevent freezing that will dry up or blow off the propeller. Instead it is a layer of hydrophobic nano coated "paint". Nano coating means that the surface is so smooth (at an microscopic level) that water droplets aren't able to grip and stick to it, leaving the surface dry even when submersed in water. And without moisture there will be no ice..
I think your first consideration should be NOT TO FLY over crowds or abeam crowds rather than icing conditions. I assume you have not seen any of accidents that happened in similar situations. Very irresponsible act! I work in aviation for years now and action like this really upset me. Please guys............ if we want to develope UAV aviation we need to work in safe and responsible way. There is not just technical development but also operational and society integration development. We dont want to lose people's trust in these two important factors of UAV science.
Again, plan thoughtful act thoughtful. SAFETY FIRST, PLEASURE LAST
Jost Laznik
www.meteocenter.eu
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