Client has asked us if we can fly our VTOL drone (3500mm wingspan) next month in a location where we can expect icing conditions. What experiences have people had? What equipment has been added to the UAV to cover for icing? And, yes apart from telling them not now as the obvious answer, any good tips or ideas so we can undertake their task.
Flying in potential icing conditions
- Thread starter AKARU-UAV
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My concern would be:
Liability flying into known icing conditions without a properly equipped aircraft. There's not a lot most UAS/UAV can do in terms of icing other than the Go/No-Go decision process. If there were to be an incident and the aircraft wasn't properly equipped then full liability and negligence would fall on the RPIC.
Liability flying into known icing conditions without a properly equipped aircraft. There's not a lot most UAS/UAV can do in terms of icing other than the Go/No-Go decision process. If there were to be an incident and the aircraft wasn't properly equipped then full liability and negligence would fall on the RPIC.
clolsonus
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I don't have a lot to add except I inadvertently flew a fixed wing drone (xuav talon) in icing conditions one time. I can share a few comments/observations from that experience.
1. I didn't realize it was icing conditions aloft. On the ground there was a really fine, very light, intermittant drizzle that was not freezing. Visibility was fine, winds were dead calm, it's hard to schedule multiple people for another day, we were all out there, so we decided to go for it. The temps on the ground were just above freezing though (I think this was an early January, Minnesota day.)
2. The flight lasted about an hour, I didn't notice anything amiss from the ground station data or the aircraft performance during the flight.
3. The area we were flying didn't have a great place for an autonomous landing (fixed wing approach needs a lot more room) so the plan was to take over manual control at the end of the survey and land manually.
4. When I took over manual control, the plane immediately dove. I could tell something was pretty far out of whack, but at this point I didn't know what, and didn't have time to think too much about it. I was able to mostly compensate by holding a *lot* of up elevator. The approach ended up being super fast and low, but I was able to spot the landing ok at the very end. I'm not a super pilot, but I guess ok enough when it counts.
5. I walked over to pick up the airplane and immediately realized what was going on. The front 1/3 of the wing was sheeted in ice. The nose was covered as well. It wasn't really visible, but you could feel it of course. This added weight (all ahead of the CG) and so completely threw off the CG and made the plane extremely nose heavy. I was super thankful my pitot tube didn't freeze over because that is a critical part of the speed/altitude control loops (total energy control system.) The ice quickly melted off in a few minutes once I was back on the ground.
Conclusion: I feel super lucky that the plane survived the experience, and I was able to rough out a smooth manual landing at the last moment. I didn't even consider the conditions could or would lead to ice build up. I feel like I learned something that day. In the future I wouldn't send the airplane if the conditions were similar. Knowing what I know now, it would be a poor decision. Knowing what I knew then ... I'm just glad I was lucky to not have a mishap.
I realize everyone else here flies multirotor, so probably they behave a lot differently, and would spend much shorter hops in the air ... so maybe the decision cutoffs would be different compared to a fixed wing? Still, I think it would be a pretty poor decision to send any drone into known icing conditions.
If anyone is interested, back at the time I made a boring youtube video showing the stitch of the imagery from that flight using our in-house designed map stitching/exploration tools:
1. I didn't realize it was icing conditions aloft. On the ground there was a really fine, very light, intermittant drizzle that was not freezing. Visibility was fine, winds were dead calm, it's hard to schedule multiple people for another day, we were all out there, so we decided to go for it. The temps on the ground were just above freezing though (I think this was an early January, Minnesota day.)
2. The flight lasted about an hour, I didn't notice anything amiss from the ground station data or the aircraft performance during the flight.
3. The area we were flying didn't have a great place for an autonomous landing (fixed wing approach needs a lot more room) so the plan was to take over manual control at the end of the survey and land manually.
4. When I took over manual control, the plane immediately dove. I could tell something was pretty far out of whack, but at this point I didn't know what, and didn't have time to think too much about it. I was able to mostly compensate by holding a *lot* of up elevator. The approach ended up being super fast and low, but I was able to spot the landing ok at the very end. I'm not a super pilot, but I guess ok enough when it counts.
5. I walked over to pick up the airplane and immediately realized what was going on. The front 1/3 of the wing was sheeted in ice. The nose was covered as well. It wasn't really visible, but you could feel it of course. This added weight (all ahead of the CG) and so completely threw off the CG and made the plane extremely nose heavy. I was super thankful my pitot tube didn't freeze over because that is a critical part of the speed/altitude control loops (total energy control system.) The ice quickly melted off in a few minutes once I was back on the ground.
Conclusion: I feel super lucky that the plane survived the experience, and I was able to rough out a smooth manual landing at the last moment. I didn't even consider the conditions could or would lead to ice build up. I feel like I learned something that day. In the future I wouldn't send the airplane if the conditions were similar. Knowing what I know now, it would be a poor decision. Knowing what I knew then ... I'm just glad I was lucky to not have a mishap.
I realize everyone else here flies multirotor, so probably they behave a lot differently, and would spend much shorter hops in the air ... so maybe the decision cutoffs would be different compared to a fixed wing? Still, I think it would be a pretty poor decision to send any drone into known icing conditions.
If anyone is interested, back at the time I made a boring youtube video showing the stitch of the imagery from that flight using our in-house designed map stitching/exploration tools:
MapMaker53
Well-Known Member
I know of no way to protect a drone from icing conditions. The location you will be flying and what lies in the vicinity of your flight path will determine your liability risk. For example, flying a remote piece of undeveloped property where the flight path remains over that property would probably create minimal risk. But I would not attempt such a flight over any developed or populated areas. In either case, there will be a high likelihood of losing your fixed-wing aircraft in a crash due to icing.
When we started our program it was built with the knowledge that we would get request/demands from upper levels to fly in questionable, less than safe, or just downright illegal missions. So we created a matrix of go/no go safeguards that we do for each flight. We like to fly so unless there is good reason not to, we fly. But the pilot has the last say always. No is completely acceptable at any time for any reason because the pilot is the one behind the eight ball. Sometimes its better to say no up front than waffle until its too late placing the pilot in a hard spot. You should be supporting your people; not boxing them in.
clolsonus
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This is true in full size aviation too ... the passengers can try to convince/pressure the pilot to go in questionable circumstances and so a pilot at any level needs to make good, clear, decisions.
There was a bush pilot picking up hunters on a lake in northern canada. When the pilot saw all their gear they had, he said no way could they get airborne in his airplane off that lake. But the hunters persisted and pointed out that the year before the pilot took them with the exact same equipment and same type of plane. Eventually the pilot relented and agreed. They loaded everything up, roared down the lake, got airborne right at the last moment, clawing for altitude they stalled and crashed into the trees at the far end of the lake. One of the hunters exclaimed, that's a 100 yard further than we got last year! (sorry it's a very old joke, so probably everyone has already heard it.)
I've enjoyed your post for a long time (how time flies) and I know you are a person I respect and has solid knowledge of UAS ops. So in that spirit, I am going to disagree that there is no way to protect a drone from icing conditions. There is. Check your local weather and if that is a possibility, they don't fly. Say no, I can not perform that flight with that risk factor. It's not safe.
The pilot always has the last word. That is your protection, ball and chain, and responsibility; to ensure the flight is as safe as you can possibly make it.
MapMaker53
Well-Known Member
What about leading edge trace heating systems. A thin, flexible strip connected to power on board that can heat the leading edge of the wing to above freezing temps. .........
It would need to be more than a "narrow strip" to be effective but something like that could be incorporated into a fixed wing aircraft with enough ingenuity and resources.
Don’t be just thinking that ice changes to CG are the only issue. The smallest amount of frost can change the laminar low over a wing or prop. Years ago I was part of the launch crew for a manned sailplane that spun in from 1000’ due to the smallest amount of frost on the leading edge of the wings. Nobody there at that incident noticed this frost or even thought that frost could be deadly, but it certainly can be.
