IEEE Spectrum interviewed the experts, and the answer is that hitting an engine (bird strike to a MD11 shown above) is not as bad as hitting the windshield. Key excerpt:
The drone will hit the leading edge of the fan blades and would probably break up into small pieces. The fan blade itself is not likely to break, in Morse’s view. “There’s a good chance it’ll take the engine out at high power,” says Morse, but not necessarily. “It’s absolutely amazing how they will still run.” In one sense, small drones appear to be less threatening than birds because drones don’t fly in flocks, so the chance of crippling multiple engines in one incident is much more remote.
But what about the lithium-ion batteries that these little drones carry? Aren’t they hard enough to create real problems for a turbofan engine? “Ice can be hard, too,” says Morse. And as for the worry about the volatile material from a battery ending up in the combustion chamber: “The engine will probably burn it up.”
In all, this expert was surprisingly calm about the possible consequences should a 1- or 2-kilogram drone strike a turbofan engine. Perhaps that’s what comes of looking at thousands of engines damaged by debris left on the runway or parts of a plane that break up in flight. Still, Morse emphasizes that when an engine ingests any foreign object, the cost of inspection and repair can be considerable, even if the mishap does not put people’s lives in peril.
“I’d be more concerned about hitting the windscreen,” says Morse. And the dangers involved with that, while considerable, hinge on the speed of collision and the mass of the object rather than its composition. Which is all to say, Exponent’s analysis of the dangers drones of this size pose should one strike an aircraft still appears reasonable enough.
Comments
It's because everyone likes a bit of hysteria Peter. :)
The 30k deaths on the roads each year go unreported but a plane with only 200-300 people crashes and it's headlines for weeks.
It never ceases to amaze me how so many people talk of Drones hitting planes when out of the the thousands of drone flights every day for the past 5 years not one single incident of a drone hitting a plane! Why don't you guys concentrate on something that is a real threat and stop babbling on about what might be? Please use common sense when dealing with issues that are not based on any facts but are made out of pure speculation. If you really want to impact public safety then start beating the drums to outlaw all motor vehicles since by far they pose truly realistic 30,000 deaths a year and at least double that in injuries. I think this discussion is stupid and does nothing to educate the public on the actual facts.
I very much appreciate Guy McCladden's comment - there are a lot of questions not addressed in the IEEE article.
Our goal here should be to promote a realistic assessment of the risks posed. At one extreme, you see popular comments that imply that people think that getting a multirotor with 1,000 feet of a passenger aircraft will cause that aircraft to immediately splinter into a million pieces. In other words, an entirely unrealistic, paranoid view. We don't want to fall into the opposite thinking - an unrealistically casual view that no "normal" sized (say 12kg and under) multirotor could possibly do much more harm to a plane than a pigeon.
One layer of all of this is that commercial passenger aircraft (particularly regional jets and larger) are very well engineered devices incorporating decades of careful analysis of numerous crashes in order to make them as unlikely as possible to loose control or crash. They have redundant engines, so even a multirotor taking out one engine in normal flight would be unlikely to cause the whole plane to be lost. I am no aviation expert, but as I understand it, losing an engine during takeoff or landing is much more dangerous, thus the basis for restricting the operation of RC model aircraft of all sorts near airport (though banning them all the way down to 0' AGL a full 5 miles from airports seems "overly cautious.") I tend to think that while there is very much a chance that a multirotor or fixed-wing "drone" will cause damage to a full-sized manned aircraft at some point, without malicious actions, it's far more unlikely than likely that a multirotor will accidentally be the sole or primary cause of a commercial passenger jet actually crashing in the next 10 years.
But with it in mind that such an event is possible, we should be operating with reasonable caution and realistic attitudes based on solid research, and not promoting either an extreme of fear and paranoia nor one of over-confidence or carelessness.
You know and I know that will never work, "Hackers" will always find a way around it. DJI was thinking about it, but changed their minds.
It does sound like a good idea.
At the moment we can change the horizontal and vertical geofence to desired values or even disable it. I wonder if in the near future the vertical fence will be set at 500 ft. with no possibility of disabling it for all UAVs sold in the US. That might stop some of the reckless flights people are doing (and posting to YouTube).
Let's hope the "you tubers" get all of this, as they are the ones that pose the most risk to the hobby. This technology is far too important to let those guys take it down. I think we all need to police our own community's of these guys. you know follow them and post how stupid they are, putting us all at risk. maybe even talk to them in person, if you know where they fly. I hope the government can see through their actions.
Common sense is sadly not all that common for some people..
If you're flying a 55lb drone however you're far more likely to have the commonsense (or at least a great enough fear of losing thousands of dollars) to not fly it into the flight paths of airliners.