Gatwick drones -what utter stupidity and selfishness

[Jakob]

Yeah, A friend with a Mavic grabbed the footage.

Model rocketry got exemptions from the 400' limit and are limited to specific locations and times. (And NOTAMs are usually issued).

[mattc]

...

It's also made me realize just how silly the new 'multi-rotor passenger' vehicles are.  They are, as mentioned, very inefficient and if you lose power, you die. With a helicopter, at least you have the chance of auto-rotating.

This is off-topic, and purely for my curiosity:

why don't the multi-rotors auto-rotate?  Are they a fundamentally different type of rotor?

[JonBuoy]

Auto-rotation and subsequent landing in a helicopter requires variable pitch high inertia rotor blades.  Drone rotors aren't particularly high inertia and, as far as I am aware, do not have variable pitch.

[Kim]

They are, on the other hand, mechanically simple.  I suppose there's a reasonable safety argument for a multi-rotor system that can cope with the failure of n rotors.

[Exit Stage Left]

...

It's also made me realize just how silly the new 'multi-rotor passenger' vehicles are.  They are, as mentioned, very inefficient and if you lose power, you die. With a helicopter, at least you have the chance of auto-rotating.

This is off-topic, and purely for my curiosity:

why don't the multi-rotors auto-rotate?  Are they a fundamentally different type of rotor?

Auto-rotation varies with forward speed. A helicopter that's hovering will descend at a higher rate than one which is gliding. https://en.wikipedia.org/wiki/Autorotation

[Kim]

In the absence of a freewheel, I expect the directly coupled electric motor would present too much mechanical load (either through eddy currents, or dissipating power in some failed-short semiconductor or whatever) to allow the rotor to usefully autorotate, anyway.

[Beardy]

They are, on the other hand, mechanically simple.  I suppose there's a reasonable safety argument for a multi-rotor system that can cope with the failure of n rotors.

That would depend on the configuration and I suspect would require the number of rotors to exceed 4. There would also need to be an over power provision in each rotor.

[mattc]

So I'd be safest in one of these, yeah?

[Kim]

So I'd be safest in one of these, yeah?

Safety is a relative concept when you're referring to helicopters 

[Ben T]

We were having a discussion about this at work and I was wondering why planes couldn't just continue anyway despite the possible drone(s) ie why is it any more dangerous than a bird.. One bloke reckoned if a drone hit a plane's wing and it caught it just right so the rotor came into contact with the wing, it could slice through the wing and completely shear it from the body of the plane. True, or bollocks?

[Beardy]

We were having a discussion about this at work and I was wondering why planes couldn't just continue anyway despite the possible drone(s) ie why is it any more dangerous than a bird.. One bloke reckoned if a drone hit a plane's wing and it caught it just right so the rotor came into contact with the wing, it could slice through the wing and completely shear it from the body of the plane. True, or bollocks?

Bollox. But that’s not the whole problem. Commercial Aeroplanes tent to be big complex machines, often with lots of people on board, and drones tend to be many varietied both in complexity and size, and more importantly, capable of carrying a wide selection of payloads. The drones in the equation would also be unidentified and essentially unidentifiable. This means that the risk is essentially unquantifiable in the short term and the only safe thing to do is shutdown operations until you can gather more information and pad out your risk assessments.

[Kim]

We were having a discussion about this at work and I was wondering why planes couldn't just continue anyway despite the possible drone(s) ie why is it any more dangerous than a bird..

I don't think it is more dangerous than a bird of equivalent mass.  They go to rather a lot of effort to avoid birds flying around airports already.

[rogerzilla]

One concern is the battery; most of a drone is plastic and will shatter if hit by a plane at 200mph (as do birds in small numbers), but the battery is tougher and could make a hole in something, maybe a fan blade.

[hatler]

One concern is the battery; most of a drone is plastic and will shatter if hit by a plane at 200mph (as do birds in small numbers), but the battery is tougher and could make a hole in something, maybe a fan blade.

Or indeed the windscreen.

[hatler]

And, for a brief while, I worked in the world of aeroplane canopies, and the testing thereof. Having foreign objects come through the screen and bonk you on the nose is not desirable.

[Gattopardo]

Or were there any drones at all?

[rogerzilla]

"These aren't the drones you're looking for."

[Gattopardo]

Move along

[mattc]

We were having a discussion about this at work and I was wondering why planes couldn't just continue anyway despite the possible drone(s) ie why is it any more dangerous than a bird.. One bloke reckoned if a drone hit a plane's wing and it caught it just right so the rotor came into contact with the wing, it could slice through the wing and completely shear it from the body of the plane. True, or bollocks?

Bollox. But that’s not the whole problem. Commercial Aeroplanes tent to be big complex machines, often with lots of people on board, and drones tend to be many varietied both in complexity and size, and more importantly, capable of carrying a wide selection of payloads. The drones in the equation would also be unidentified and essentially unidentifiable. This means that the risk is essentially unquantifiable in the short term and the only safe thing to do is shutdown operations until you can gather more information and pad out your risk assessments.

Doing the risk assessment doesn't make anyone safer.

But yeah, someone will need to *show* that they've assessed the risk, that's the way current HSE legislation works. What IS stupid is not assessing the risk of drones a loooooong time ago. There are many risks that are hard to quantify in the real world. It's impossible to rule out the firing of a SAM somewhere nearby tomorrow - but it's vv unlikely. I'm pretty sure that the Drone Damage Assessment would say:
"collision with small object producing medium damage to plane" - "probablity of impact: very very low"
"collision with small object producing very minor damage to plane" - "probablity of impact: very low"

In which case someone would make the standard gut-based desicion, and unless they were extremely risk-averse - for political, or weird job-security issues - they'd probably say:
"Carry on, but let's keep an eye on things."

[See also: the hundreds of government sites that have had big "Heightened Awareness" signs at the entrance for about 5 years ... ]

[Gattopardo]

They are, on the other hand, mechanically simple.  I suppose there's a reasonable safety argument for a multi-rotor system that can cope with the failure of n rotors.

Chinook seems to fit that bill.

Proof being I am still alive after chinook crashed (unplanned landing with damage to the vehicle) and was saved by the fact the rotors auto rotated.  There was a person who used his whole body weight hold a lever down in the cabin.

[Kim]

They are, on the other hand, mechanically simple.  I suppose there's a reasonable safety argument for a multi-rotor system that can cope with the failure of n rotors.

Chinook seems to fit that bill.

Fairly sure a the rotors of a Chinook operate as a single point of failure.  Aren't they coupled so they don't end up bashing each other?  And even if that wasn't a problem, with a single rotor operating there'd be nothing to counteract the torque, so it would have to go into autorotation anyway.

[hatler]

With only a single rotor on a Chinook operating surely one end would drop, and then the working rotor wouldn't be much use.

But as Kim says, the rotors are linked.

[Beardy]

Chinook rotors overlap and interleave and I believe are physically interlinked. The chinook also has twin engines. Even so, given their propensity for falling out of the sky, I’d have to be in a pretty bad place to willingly get on board one.

[Jakob]

So I'd be safest in one of these, yeah?

Again, very inefficient compared to a single rotor. Coaxials are slowly making a comeback in the kit/experimental category.  A friend of mine just bought one of these:
http://eng.rd-heli.ru/

As for 'why planes didn't fly', one is that aviation is *extremely* risk adverse. Common saying is "If there's any doubt, there's no doubt'.

Drones can do significant damage to an airliner. How much, is really hard to say.
https://www.youtube.com/watch?v=QH0V7kp-xg0

Here's a video of a typical 'consumer' drone hitting a Bonanza wing. It got some criticism, as the drone was fired at 200mph, a speed a fair bit above a typical approach speed, but still. Shit can happen and you hit the wrong bits, things can go wrong. The initial reports was that it was a 'pro' level drone, which can be anything from 5kg up (The Phantom is about 1.5kg, I think).
 So, in that light, yeah, stopping operations was reasonable. Stopping it for 2 days, based on spurious reports? Not reasonable at all and I still believe it the decision to stay closed was agenda driven.
I still don't understand why there has not been a single picture of the drone. This is UK, forchrissake, the country with probably the highest level of surveillance in the world.

[andytheflyer]

I still don't understand why there has not been a single picture of the drone. This is UK, forchrissake, the country with probably the highest level of surveillance in the world.

'cos there wasn't one...…..