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Re:Lilium – Electric vertical take-⁠off and landing jet by aphextron on Friday April 21, 2017 @03:33PM (#14168654)
As a pilot I would never step foot in this thing. The thought of being in an aircraft with zero aerodynamic control, or ability to glide in a dead stick situation is a complete nightmare. It doesn't matter how redundant your systems are if you have a fundamentally unstable airframe with no yaw control. In a total power loss situation, you must have some type of glide profile. All other forms of aircraft have this. Such a design would be fine for drones, but this will never carry humans.
Re:Lilium – Electric vertical take-⁠off and landing jet by tristanb on Friday April 21, 2017 @03:39PM (#14168725)
Rockets, balloons, most military aircraft? Shove a ballistic parachute on it.
Re:Lilium – Electric vertical take-⁠off and landing jet by aphextron on Friday April 21, 2017 @03:43PM (#14168777)
> "Rockets, balloons, most military aircraft? Shove a ballistic parachute on it."

As far as I know, no rocket or military fighter jet has ever been certified to carry paying passengers for exactly this reason. We're talking about shuttling people around, not highly trained test pilots.

Balloons are actually far safer than fixed wing aircraft for other reasons. It would take a complete loss of the canopy for a balloon to fall out of the sky. When they run out of fuel, they just drift slowly to the ground.

Ballistic parachutes are a last resort option, and add a large amount of weight and complexity to the aircraft. Not to mention that they do not scale up to larger passenger aircraft. It's not even comparable to the safety afforded by a stable airframe.

Re:Lilium – Electric vertical take-⁠off and landing jet by tristanb on Friday April 21, 2017 @03:46PM (#14168808)
You cant dead stick a cessna in an urban environment, and current ballistic parachutes aren't that heavy.

https://aviation.stackexchange.com/questions/24946/what-is-t...

Re:Lilium – Electric vertical take-⁠off and landing jet by aphextron on Friday April 21, 2017 @04:02PM (#14168949)
>You cant dead stick a cessna in an urban environment, and current ballistic parachutes aren't that heavy.

Except a ballistic parachute does absolutely nothing for you in the scenario where > 90% of accidents happen: take off and landing. Even the most advanced BRS systems on Cirrus planes require 1000 feet AGL. There's simply no getting around the basic physics of this problem.

Re:Lilium – Electric vertical take-⁠off and landing jet by nickthemagicman on Friday April 21, 2017 @05:00PM (#14169398)
Yeah but dead sticking is less effective during take off and landing as well.
Re:Lilium – Electric vertical take-⁠off and landing jet by falcolas on Friday April 21, 2017 @05:15PM (#14169481)
I watched someone who wouldn't make the runway (pilot error, didn't switch the fuel tanks fully on approach) dead stick onto a perpendicular highway.

With a light plane, you can do a lot with a dead stick. They have remarkably generous glide slopes (nearish to a mile horizontal travel for every 1,000 vertical feet). Not to mention being inherently stable whether under power or not.

Re:Lilium – Electric vertical take-⁠off and landing jet by tristanb on Friday April 21, 2017 @04:06PM (#14168983)
Well a 0/0 safety system seems like a solvable problem in the scheme of things. airbag + chute? Who knows.
Re:Lilium – Electric vertical take-⁠off and landing jet by monkmartinez on Friday April 21, 2017 @06:33PM (#14169944)
You can't dead stick most aircraft in an urban environment. Unless you are Sully...
Re:Lilium – Electric vertical take-⁠off and landing jet by tristanb on Friday April 21, 2017 @03:47PM (#14168816)
Let me clarify that, you can dead stick a cessna and land it outside your local bar in NYC (someone did) but its not easy.
Re:Lilium – Electric vertical take-⁠off and landing jet by jacquesm on Friday April 21, 2017 @08:11PM (#14170416)
Re:Lilium – Electric vertical take-⁠off and landing jet by SJC1 on Monday April 24, 2017 @12:04AM (#14181915)
Once a parachute is deployed there is no control among many high rise buildings.
Re:Lilium – Electric vertical take-⁠off and landing jet by tylorr on Friday April 21, 2017 @05:27PM (#14169563)
On the technology page under the safety first section they talk about a parachute being installed as a last resort.
Re:Lilium – Electric vertical take-⁠off and landing jet by walrus01 on Friday April 21, 2017 @06:56PM (#14170099)
If equipped with a parachute like a Cirrus I would not be so scared of it. In its current iteration it's about as scary as the eHang giant octocopter.
Re:Lilium – Electric vertical take-⁠off and landing jet by bobsil1 on Friday April 21, 2017 @07:54PM (#14170347)
Parachutes generally need 1K feet to be effective, and VTOL cabs will operate at fairly low altitudes. Maybe there are special ops low-altitude parachute designs that can be adapted for airframes.
Re:Lilium – Electric vertical take-⁠off and landing jet by ENGNR on Friday April 21, 2017 @11:41PM (#14171009)
As a non-pilot, that's ultimately the reality every time we fly already. Sure there's redundancy, but ultimately if things go wrong all we can do is sit powerlessly in our chair as the ground roars up at us.
Re:Lilium – Electric vertical take-⁠off and landing jet by manigandham on Saturday April 22, 2017 @04:31PM (#14174587)
The post is talking about unpowered glide profile - the vast majority of air travel is in commercial jetliners which can and do glide, providing a major advantage in case of problems.
Re:Lilium – Electric vertical take-⁠off and landing jet by dm_i386 on Friday April 21, 2017 @03:39PM (#14168720)
How is the glide profile any worse than a helicopter's?
Re:Lilium – Electric vertical take-⁠off and landing jet by dingaling on Friday April 21, 2017 @03:42PM (#14168761)
Helicopters glide or 'autorotate' tolerably well after engine or driveshaft failure, at least enough to land controllably.

In the R22 two-seater the best glide ratio is about 4:1 ( 4ft horizontal for 1ft drop ) and those at my local airfield practice autorotation to landing all day long.

Apparently the worst helicopters for autorotation are those with Kamov's superimposed coaxial rotor system, which struggle to reach 2:1 for some aerodynamic reason I don't know.

Re:Lilium – Electric vertical take-⁠off and landing jet by ominous_prime on Friday April 21, 2017 @03:46PM (#14168806)
Helicopters glide quite nicely. Learning to autorotate is something you learn early on when getting your license.
Re:Lilium – Electric vertical take-⁠off and landing jet by aphextron on Friday April 21, 2017 @03:44PM (#14168784)
>How is the glide profile any worse than a helicopter's?

This is a common misconception. Helicopters can glide to a landing just like airplanes.

Re:Lilium – Electric vertical take-⁠off and landing jet by TylerE on Friday April 21, 2017 @03:44PM (#14168779)
In a helo you can attempt auto-rotation, which while tricky at least gives you a fighting chance.
Re:Lilium – Electric vertical take-⁠off and landing jet by gdudeman on Friday April 21, 2017 @03:45PM (#14168791)
Is this dissimilar to a helicopter though?
Re:Lilium – Electric vertical take-⁠off and landing jet by astrodust on Friday April 21, 2017 @04:06PM (#14168978)
A helicopter can auto-rotate, though that's really the least-bad option if you're in that sort of situation. It turns an assuredly fatal scenario into a hopefully, maybe, possibly survivable one: https://aviation.stackexchange.com/questions/14605/how-does-...

Here's a demonstration: https://www.youtube.com/watch?v=BTqu9iMiPIU

Re:Lilium – Electric vertical take-⁠off and landing jet by jimbokun on Friday April 21, 2017 @08:23PM (#14170464)
Haha! That Neil DeGrasse Tyson, what a dummy.

(Good sport, though. And I also thought a helicopter would drop like a rock without power.)

Re:Lilium – Electric vertical take-⁠off and landing jet by astrodust on Saturday April 22, 2017 @06:08PM (#14175105)
It drops like a rock if the Jesus Nut (https://en.wikipedia.org/wiki/Jesus_nut) fails, but that situation is freakishly rare.
Re:Lilium – Electric vertical take-⁠off and landing jet by lookACamel on Saturday April 22, 2017 @06:02AM (#14171806)
So similar to how a maple seed glides?
Re:Lilium – Electric vertical take-⁠off and landing jet by astrodust on Saturday April 22, 2017 @05:29PM (#14174925)
Not really. Watch the video. A maple seed has less control over how it spins.
Re:Lilium – Electric vertical take-⁠off and landing jet by snerbles on Friday April 21, 2017 @04:04PM (#14168969)
Helicopters can auto-rotate, "gliding" on the momentum of the main rotor. This allows for a controllable landing under loss of power.

There have been rare cases where a mechanical failure seizes the main rotor, such as the crash of the WNBC news chopper (N8617B) in 1986. This particular incident was caused by poor maintenance, however.

https://en.wikipedia.org/wiki/Autorotation

http://www.check-six.com/Crash_Sites/Dornacker-N8617B.htm

Re:Lilium – Electric vertical take-⁠off and landing jet by jacquesm on Friday April 21, 2017 @05:34PM (#14169604)
Roughly as dissimilar as a sack of bricks versus a helicopter. Those small ducted fans will do absolutely nothing while you fall down. Maybe they'll spin a little bit to recharge the batteries, sort of a built in confusion generator for the people doing the autopsy: "Why didn't they just land the thing, it's got some charge left?".
Re:Lilium – Electric vertical take-⁠off and landing jet by ominous_prime on Friday April 21, 2017 @06:08PM (#14169823)
Where do people get the idea that helicopters just fall from the sky when there's a power failure?

Do people think that others are flying around everyday in machines that will likely kill them in case of a malfunction? Is the media is covering up all the helicopter related fatalities?

Re:Lilium – Electric vertical take-⁠off and landing jet by jacquesm on Friday April 21, 2017 @06:22PM (#14169896)
People just don't realize there is such a thing as auto-rotation.
Re:Lilium – Electric vertical take-⁠off and landing jet by jimbokun on Friday April 21, 2017 @08:24PM (#14170468)
Yes, that is exactly what I thought. Me and Neal DeGrasse Tyson!
Re:Lilium – Electric vertical take-⁠off and landing jet by whazor on Saturday April 22, 2017 @02:52AM (#14171422)
The plane they are planning to build looks like it could glide by itself.
Re:Lilium – Electric vertical take-⁠off and landing jet by esemor on Friday April 21, 2017 @03:52PM (#14168876)
This guy!