Re:Lufthansa flight has near-miss with drone near Warsaw
by simcop2387 on Tuesday July 21, 2015 @03:42PM
(#9925182)
They can. From what I've read the real problem is much like birds. If they get sucked into the jet engine then they can do a huge amount of damage. More than a bird even because of the fact that you've usually got a good bit of metal and a lithium battery or two. That's enough to take out the engine just like a bird but with the lithium battery that's going to get splattered around there's an increased chance of fire starting that could make even losing one engine a really bad prospect. Combine that with the fact that the plane is likely to be at a low altitude and it's unlikely that the plane will be able to glide somewhere it can safely crash land at either an airport or long stretch of road.
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Re:Lufthansa flight has near-miss with drone near Warsaw
by kordless on Tuesday July 21, 2015 @04:10PM
(#9925388)
> More than a bird even
A lithium battery is going to get chopped up and spit out the rear of the engine - if it manages to get in the intake to begin with, which is a huge if. There's ZERO chance any of that lithium would stick around long enough to cause a 'fire', whatever that means. It's not called a 'jet' engine for nothing.
Re:Lufthansa flight has near-miss with drone near Warsaw
by simcop2387 on Tuesday July 21, 2015 @04:36PM
(#9925599)
Given that a big part of a jet engine is that there's a large series of rotors to perform the compression of the air intake as it streams in[1], and then constricts the space to get even higher compression before the combustion chamber there's a good chance of things getting stuck once the primary rotor has been damaged by something going into it. That's the primary way that birds and other debris disable a single engine. They don't usually cause a fire because they're not likely to combust/explode on being punctured or torn[2].
[1] https://upload.wikimedia.org/wikipedia/commons/4/4c/Jet_engi... [2] https://www.youtube.com/watch?v=hhJf9pJ6gOk ; many more just look for lipo explode
Re:Lufthansa flight has near-miss with drone near Warsaw
by Phlarp on Tuesday July 21, 2015 @04:20PM
(#9925468)
How much experience do you have with the lithium polymer batteries commonly used on hobbyist drones?
I've been flying for a little over a year now and personally seen some pretty gnarly LiPo failures in that time.
I would _not_ want to be flying on a plane with one of those hitting the turbines. Would you?
Re:Lufthansa flight has near-miss with drone near Warsaw
by kordless on Saturday July 25, 2015 @01:58PM
(#9948376)
Howdy! I've been flying all sorts of R/C for 25 years, so quite a bit of experience. Had them splode/catch on fire occasionally. Jet engines are quite a bit bigger than said batteries and the flows through them are sufficient to exhaust most, if not all, of the battery out the ass end before the lithium could experience thermal runaway (which is what li-ion fires are).
Re:Lufthansa flight has near-miss with drone near Warsaw
by astrodust on Tuesday July 21, 2015 @04:29PM
(#9925550)
I think the worst thing is not the fire, but what happens if the wiring gets gummed up on some blades and unbalances the engine. These things turn at a crazy number of RPM, so even a small amount of weight off-balance could cause them to vibrate and self-destruct catastrophically if it hit the right harmonic.
Re:Lufthansa flight has near-miss with drone near Warsaw
by simcop2387 on Tuesday July 21, 2015 @04:39PM
(#9925615)
Given the speeds I'm not even sure it'd take that. The debris being sucked in I think would be enough to break/bend a blade or two which would unbalance it just as easily. Making even more debris for the rest of the engine.