EVTOL drones to carry people

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OK so here is a recent EVTOL article about an effort from Airbus:
CityAirbus NextGen - Urban Air Mobility - Airbus

Notice how this new “million flies” try to enlarge drones to carry people!

What made drones possible?

  1. Low payload weight,
  2. short flight time,
  3. inanimate payload (no passengers)

These three factors allowed:
a) an aerodynamically inefficient method of elevating it (model airplane propellers)
b) electric drive (short range allowed a relatively small amount of extremely heavy batteries)
c) less worry about safety and the “dead zone” near the ground - too low to use a chute if needed
d) no ability to autorotate in case of engine failure like a heck-of-a-lopter.
e) the possibility to deliver packages

In spite of all these factors, people are in love with drones! Now they are calling them “flying cars!” But there is a long history of flying cars - they aren’t very good at either being a car or being an airplane.

Also, I saw a video of a Blackhawk helicopter flying over some Eucalyptus trees with people picnicking below: The helicopter blew all the largest branches right off the trees, onto the ground below, and the people were running away! Probably some people were hit! It seems that wannabe flying-car inventors underestimate the impact of the downdraft from hovering.

Why do all these companies keep “developing” these extra-large drones, yet they never enter actual service? Remind you of anything? I guess the idea is you can ignore the “dead-zone” of low altitude flight where any failure will dump you onto the ground without time to deploy a chute or anything else. I guess they think their electronics, wiring, cables, connections, motors, computers, controllers, sensors, algorithms, batteries, etc., will be so failure-proof that “What could possibly go wrong?”.

I’m just thinking, despite any claims of safety, it would be a long time before I would get in one! Watch a few videos about airplane crashes. Nobody thinks it can happen to them! It’s always something nobody realized, that causes crashes. It’s always a big surprise. it’s often caused by a computer!

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I hope you are not comparing the AWE community to those tinfoil hat guys in the flying car camp?

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Hi Tallak: Glad you picked up on that! :slight_smile:

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Latest news on EVTOL: The one in China that has carried a few passengers published a video of a supposed motor failure and a ballistic parachute recovery.
The problem with humans onboard drones is they do not have an ability to glide to a landing, as do helicopters and airplanes.

Note that below a certain height, the parachute(s) do not have time to open, so, like paragliders suffering a canopy collapse, you will be injured or killed. parachutes are useless below a certain height that is still too high to survive a fall from.

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https://www.reddit.com/r/AskEngineers/comments/17oajtf/what_are_the_benefits_of_evtol_aircraft/

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There is many multicopter drone prototypes that have redundancy in motors and propellers so multiple of them can fail and the drone will keep flying. I would say a multicopter with redundant motors and propellers is even safer than fixed wing aircraft or helicopters because the multicopter can keep flying like normal on the redundant motors and propellers to a normal landing, while a fixed wing plane or helicopter has to immediately find a suitable spot for a emergency landing within reach of gliding or autorotating.

Plus a electric motor us pretty unlikely to fail. Compare that to the gearbox and bearings on a helicopter where a single point failure is catastrophic and unrecoverable, like we have seen on some accidents where the rotor has left the rest of the helicopter after gearbox failures of just one planet gear.

The battery pack on a multirotor can be divided into redundant units as well.

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It kind of reminds me of “Self-driving cars”. Turned out to be a lot more difficult than “the experts” predicted.
In aviation of any kind, ONE THIING you quickly realize is IT IS WAY MORE DANGEROUS than you thought. Half the people I knew in hang-gliding are dead or have been hospitalized with severe injuries, often blaming it on a mountain bike accident etc. Out of the few general aviation (light plane) pilots I know, or know of, a few are dead from crashes, or they quit flying before they were “next”. These were some of the most highly regarded pilots too, who appeared in airshows etc. One owned a propeller company and helped me get started in AWE long ago. 4 people died in that one. Never made it past the fence at the end of the runway. Well actually they took out the fence, and with a full tank of gas, turned into a fireball. Obviously it was unplanned.

The problem with aviation safety is, there are SO MANY things that can go wrong, from forgetting to do something before takeoff, to a failing component, to just using bad judgement and getting yourself into something you can’t get out of. It’s always unexpected.

We met a lady driving an electric Hyundai Kona yesterday at Tractor Supply. We asked her how she liked it. She said she liked it, but the next thing was how the main, 1000 lb., $20,000 battery had failed in Las Vegas, and Hyundai had to tow it all the way back to Southern California and install a brand new battery. As though that was just some little thing - the main component stopped working. She also remarked how Hyundai was “a Japanese company”. I tried to tell her “No, Hyundai is a Korean company”. She said “Well it’s Korean AND Japanese”, then went on to tell us all about how the world works. We’re like, OK lady, you didn’t even know Hyundai was Korean??? I thought everyone knew that! I’m thinking "here we go again, another IDIOT!
But I digress
My point is, when your “can’t possibly fail” components go bad out on the road, you can just pull over and call a tow truck. When it happens in the air, you are dead. :frowning:

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Redundancy keeps the worlds most dangerous and critical industry’s running. Like nuclear powerplants, etc. And it is trivial to implement on multirotor drones.

On helicopters on the other hand single point failures can lead to catastrophic unrecoverable situations. Like fatigue cracks in a gear causing the gearbox to explode and the main rotor dethatching:

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Yes, trivial as long as no people are onboard. I’ve heard all the “arguments” for how safe they “should be”. About 15 years ago, Joby was involved in AWE. Realizing their cause was hopeless, they quickly pivoted to multi-rotor drones for carrying people. I guess the main use is supposed to be getting people to the airport on time. Why they would pick that as the main use, I have no idea. Meanwhile, good luck getting a drone flight anywhere - whether to the airport or anywhere else. During that amount of time, regular airplanes went from a curiosity to airlines with scheduled flights. The multi-rotor drones are still mucking around, waiting for “certifications”, etc. Sure, they are “supposed to be a” simple slam-dunk, easy success, based on all the little camera drones out there. Just like AWE was “supposed to be” a slam-dunk, easy success, based on all the fun windsurfers were having out there. If it’s so easy, why are they still “getting ready to get ready”, after a decade and a half? And they can’t really blame certification issues, because there are plenty f places they could fly if there were a compelling product available. Yes I saw the one in China. You couldn’t pay me a million dollars to get in and fly. When things go wrong in aviation, its always something “unexpected”.

14 years ago, a friend told me I should put down a deposit on an Icon airplane. It was supposed to be the safest thing in the sky, with a ballistic parachute in case anyone had any doubts about its safety. Then the head of the company got killed flying up a box canyon in one. “What about the parachute?” everyone asked. Nobody had a good answer.

Then a famous baseball player crashed another one.

So many new aircraft turn out to be unsafe, even the 737 Max by Boeing! All that computer power! All that redundancy! “What could possibly go wrong?” But there’s always one more thing to go wrong! :slight_smile:

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So i guess you never take a trip on a plane? Or drive a car? Or ride a bike? Or ride a train?
Because after all anything can go wrong at any moment and send you to an early grave…

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This line of research and development has been going on for 15 years, probably a billion dollars spent, with nothing in the air on a regular basis.
So you saying it is safe, here on the internet, doesn’t really add anything to the discussion that people haven’t heard.
What is your theory why none of these efforts ever gets anywhere, and so are always set in future-tense? If everything is so perfect with these propellicopters (yes that is my own word, dang it!) why isn’t anyone flying around in them? It didn’t take that long for electric cars to gain a foothold.

If you were involved in aviation, you wouldn’t be so dismissive of its terrible safety record. Go on Youtube and watch a thousand plane crash videos, including many many jetliners. Sure they make a statistical case for jetliners being safe - per mile traveled, not per unit time spent on a plane. I know people who were killed in a jetliner crash. They were rich and had just inherited a fortune, then they were dead.

Small planes and general aviation is right down there with hang-gliding and skydiving in (lack of) safety. I believe the reason you don’t see people in drone-type propeller-lifted aircraft is the developers understand that they are not safe. Sitting around typing on your computer, sure you can “say” they “are safe”. Apparently, not too many people are confident enough to put that to the test by getting in and flying in one. You do the math. After 15 years, if it were all as simple as you seem to think, we’d be seeing them flying somewhere, for some purpose. Everyone who flies in any way understands the basic problem: They can’t glide. Therefore they are dependent on maintaining power to remain airborne, which cannot be guaranteed. Therefore they are not safe for human consumption.

Also, don’t forget, it’s one more case of placing your life under the control of software, written by imperfect humans. Software is supposed to be what makes these aircraft possible, but then again, software is famous for causing crashes in aviation. Software has glitches and fails when it encounters a situation not foreseen by the programmers.

Then there are mechanical failures. Sure you can point to a mechanical failure on a helicopter. Thats because people USE helicopters. They accumulate many hours in the air. the reason you can “say” drones lifted (inappropriately) by airplane propellers “are safe” is because there are none accumulating any flight time. A ship is safe as long as it never leaves the harbor!

Also, take your average propeller-lifted experimental prototype, and throw a rope or cable at it, and see what happens. A tangled, falling mess.

Besides that, an efficient aircraft moves a lot of air a little bit, to remain airborne. These airplane propellers move a little air, a lot, which is less efficient. And electric power for aircraft is also inefficient because the key to aircraft is light weight, whereas batteries are heavy. This is all well-known.

The whole concept is inefficient and dangerous. Not saying someone might not find a use for one if they have the guts to bet their life on it, but so far nobody is taking that chance. There are obviously reasons they aren’t flying regularly, just like AWE.

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Multicopter energy efficiency would not be the main cause why flying cars «dont take off». I think safety is more or less the only hurdle. Uou can solve some safety issues with redundancy but only some. I think the problem is you need x flight hours without a crash before you put people on it, and accumulating those x hours is not possible until these things are safe, and then time just flies by. As an investment it doesnt make sense at some point. Also, the usefulness of such a drone is not big enough to make any sense to risk your life. Very short range makes it better for possible early adopters to rather just take the car. So maybe the market also needs the level of service to reach a really high bar before it appears?

Safety in redundancy can be achieved, but to design a totally redundant system is hard and I dont see a lot such systems around. My guess is development teams are underestimating how hard this and other things is.

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All well and good Tallak, but a car doesn’t need 4 extra wheels “just in case” and an airplane doesn’t need an extra set of wings. If your engine quits, you can always glide in. I think helicopters do have more of an issue, if their engine quits too low to get autorotation fully implemented. Airplane propellers were never designed for directly lifting an aircraft. It’s the wrong tool for that job. Sure they can make it work fine at a small scale, with no passengers.
By the way, I heard something flying overhead here the other day, and I couldn’t decide if it sounded like an airplane or a helicopter. It was on Osprey. They are always crashing too, but supposedly, statistically, they are 'pretty safe". We’re also right under the test flight path for Predator drones.
I could just imagine some new person who didn’t know the factory was nearby wondering what’s going on with that.
Anyway, I think a big issue is whether software can solve every issue. There are obviously many many things that could go wrong, despite any attempt at “redundancy”. By the way, sure you coud have 100% redundancy - and it would weight twice as much! :slight_smile:

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Very often redundancy is zero weight cost, or close to zero. But the issue is fools fools fools writing the software. It is hard, I think only a few people can pull it off. Also its not easy to see why it is so hard, until you realize your redundancy is adding more downtime than redundancy gains

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I still like the idea of redundant systems onboard.
Had a personal - so this is how it ends - moment, over the North sea in an S61 which lost control of the pitch of the tail rotor.
Hardware. The control wire popped off the sheave somewhere in the arse end. Amazing pilot. Still here

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Like the software for the 737 Max that dove the plane into the ground based on input from only one out of 2 pitch sensors, which are known to fail by everything from ice to insects?

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Holy Cow Roddy! Not sure what redundancy might have solved that one, but losing the tail rotor is usually pretty bad!

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No just around 150 years or so…

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That is FUNNY! Good one!
Actually though, you gotta remember, electric cars were the original main type of cars, way back in the late 1800’s. They were for the rich - like Henry Ford’s wife.
It was only after they caught on, and people got used to driving cars, that they needed more range and to not be tethered to a barely-existent-in-many-areas electric grid. Too bad they didn’t check out the periodic table of the elements and notice lightweight lithium was in the same column as heavy lead! Where the hell was Elon Muskmelonhead back then? :slight_smile: