Others have built human-scale multirotor electric aircraft. eHang has been demoing theirs for years.[1] eHang has 16 motors and 16 props. They've been through a few iterations on the design, so they're past the prototype stage. But they seem to be kind of stuck. These drone-based things are so limited in range due to battery capacity and weight constraints that they are not yet useful.
Aviation Week and AAM have a "reality index" for companies in this space. Currently, Joby Aviation and Volocopter lead, followed by a three-way tie between Archer Aviation, Beta Technologies and EHang.[2]
Joby [3] is a 6-prop tilt rotor with a minimal wing. It can take off and land vertically, but flies more like an ordinary aircraft. This takes less energy than helicopter mode. Joby's range record is 151 miles in a 77 minute flight, going round and round over an airport. This is a complicated aircraft and takes a skilled pilot plus considerable computer power.
Volocopter [4] has 2 seats, 18 props, and really good renders on their web site.
They're demoing at the Paris Air Show, starting tomorrow. They're working, slowly, towards type certification in Europe, then certification as an air carrier. Range limit maybe 60 miles.
There's still the clown car of the industry - Moller. Real Soon Now for over 50 years.[5] Apparently "inactive", but the web site is still up. They once did get a prototype, running on a large number of small Wankel engines, to hover while connected to a crane for backup.
There's also the Jetson One, which looks real, and they're also accepting orders.
..Although I'm not sure I would feel safe flying a 4 rotor thing. Well, they're 8 but in 4 pairs on the same axis; a big enough bird or a hit on something hard enough would probably destroy 2 propellers at the same time, and the aircraft is rated for sustaining the loss of only one. Cool nonetheless.
I’ve often wondered if smallish internal combustion engines (with variable pitch propellers presumably) could increase range at the cost of some weight. Maybe someone familiar with the trade offs could comment?
Well yes, helicopters with internal combustion engines have been working fine for a while now. But if the engine is mechanically coupled to the rotor then it will need variable pitch blades in order to maintain control. Combustion engines can't change speed as quickly as electric motors can.
It's a powered ultralight aircraft, which is covered under part 103 of the FAA regulations.
There are no licensing, knowledge, age, experience, or medical requirements for pilots of ultralights.
For the aircraft itself there are no certification standards, other than it has to meet the definition of a powered ultralight. That is:
-only one seat
-is only used for recreational or sport flying
-does not have an airworthiness certificate
-weighs less that 254 pounds empty (not counting safety equipment and floats)
-has a maximum fuel capacity of 5 gallons
-does not exceed 63 mph in level flight at full power
-power off stall speed does not exceed 28 mph
Ultralights can only be flown between sunrise and sunset, unless they have an anti-collision light visible for 3 miles and are in uncontrolled airspace in which they can fly 30 minutes before sunrise to 30 minutes after sunset.
They cannot be flown over any congested area or over an open air assembly of people.
This seems wild to me (I believe you, it's just wild). A quadcopter has to be registered above 250 grams, this requirement goes away if there's a human inside?? Feels like this area between an unmanned drone and the smallest manned airplane is missing regulation.
I don't see how that fits under 254 pounds, unless they stretch the meaning of safety equipment. Most ultralights I've seen are the thinnest scaffolding for a wing or parachute holding a tiny engine and a seat. Maybe the materials are some new composite?
I'm also curious how the FAA will determine max fuel capacity for an electric aircraft. Does battery weight count in the "empty" calculation? Is there an amp-hour-to-gallon average? Could I make a frame out of batteries to get "free weight" towards my design?
It is exempt from license requirements, not FAA regulations. Ultralights and paragliders are the same way. Most anyone can buy and fly a powered or unpowered ultralight without a license as long as they comply with the FAA's strict regulations:
If this isn't a scam it's bullshit, for a number of reasons:
- in the cities of developed countries is forbidden to fly drones so big almost everywhere;
- in the same cities is forbidden to fly or landing ultralight plane ;
- this vehicle falls in both the previous categories, so that photos in urban areas are bullshit : you can't use that to go to the office and no cities will give the authorisation to rent that stuff as electric bike to everyone. That will never happen !
- How you can possibly guarantee the security with that kind of vehicle around, against criminal and terrorist ? Providing Stinger Missiles and Apache helicopters to the police ? Shooting down drones with machine guns inside the city in WWI style duels ? Oh, please ! :-)
- I imagine flock of this toys, piloted by drunken pilots, raining down Saturday night ! :-)
That admitting that this project is feasible: observing the photos of that vehicle, I can not see space for the batteries because, as described in the specs, it should float, so the landing support should be empty to guarantee buoyancy, they say batteries are far from the pilot to guarantee thermal protection, so they can't be under the seat and above the cabin should be the "ballistic parachute". So where are they ? In the pylons of the motors ? But in that case they won't be easily interchangeable are declared in the specs ! And that magic "hybrid technology" that should solve all the autonomy problems? No details at all , another red flag. So the photos of the "prototype" IMHO are more a Photoshop exercise than reality.
According to this video [0], each motor has its own battery. So presumably they're in the cylindrical enclosures under each motor (it briefly shows one being replaced).
I just saw the video, I think that's plausible and notably the test flight seems last only few minutes without the magic "hybrid technology" they mention in the presentation, as expected. I agree with one think the guy says in the video, the only purpose of that machine is to make people enjoy the thrill of flight, aka amusement parks.
Its remote controlled as well as being locally piloted. Its a drone that happens to also have local controls.
“Every second of your flight is monitored by our highly trained and licensed primary and secondary flight controllers, with whom you’ll have radio communication who and can take over remote control of your aircraft at any time, if necessary.”
Yeah, it says "LIFT doesn't sell aircraft, we're the first company in the world to offer electric multi-rotor flying as an experience". Their marketing is also to investors and they might sell aircraft in the future but right now it's just short supervised (ground station) flights.
Is many small propellers really more efficient than few big ones? Even if they didn't want to make a mini-helicopter, they could've also went with a 3-4 rotor design.
I worked in this space for years. The answer is no. If you evolve a multirotor design to be more and more efficient you will end up with fewer, larger rotors, until the time comes that you require variable pitch to have sufficient control bandwidth. At which point you have a helo.
You can take it a step further and have a counterweighted single blade propeller, which is the most efficient.
That being said, this is only aero efficiency. Once you start to add electric motor efficiency, things get interesting. To generate thrust with lower number of blades you need to have large torque torque to put into the prop , which means the motor has to be a low Kv (Kv = rpm/volt, and a low Kv means a high Kt where Kt = torque/amp), to keep the current lower to lessen electrical power losses. Or use a reduction gearbox. Both of the above necessitate a bigger package and more weight, which requires more thrust, and so on.
There is a place in this design space where having multiple rotors is actually more efficient for the overall flight envelope.
I'd assume it's more about redundancy - 1/18 failed motors vs 1/4 would be much safer to land. Also means the replacement motors would be cheaper (individually). Like the starship booster.
And having more redundancy presumably means you can build each one cheaper and don't have to inspect them as much.
Smallish helicopters aren't that expensive. Maintenance and fuel are though. Going electric already helps with the fuel, going for many motors helps with the maintenance.
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Others have built human-scale multirotor electric aircraft. eHang has been demoing theirs for years.[1] eHang has 16 motors and 16 props. They've been through a few iterations on the design, so they're past the prototype stage. But they seem to be kind of stuck. These drone-based things are so limited in range due to battery capacity and weight constraints that they are not yet useful.
Aviation Week and AAM have a "reality index" for companies in this space. Currently, Joby Aviation and Volocopter lead, followed by a three-way tie between Archer Aviation, Beta Technologies and EHang.[2]
Joby [3] is a 6-prop tilt rotor with a minimal wing. It can take off and land vertically, but flies more like an ordinary aircraft. This takes less energy than helicopter mode. Joby's range record is 151 miles in a 77 minute flight, going round and round over an airport. This is a complicated aircraft and takes a skilled pilot plus considerable computer power.
Volocopter [4] has 2 seats, 18 props, and really good renders on their web site. They're demoing at the Paris Air Show, starting tomorrow. They're working, slowly, towards type certification in Europe, then certification as an air carrier. Range limit maybe 60 miles.
There's still the clown car of the industry - Moller. Real Soon Now for over 50 years.[5] Apparently "inactive", but the web site is still up. They once did get a prototype, running on a large number of small Wankel engines, to hover while connected to a crane for backup.
[1] https://www.ehang.com/
[2] https://aviationweek.com/aerospace/advanced-air-mobility/lea...
[3] https://www.jobyaviation.com/
[5] https://moller.com/
[4] https://www.volocopter.com/
..Although I'm not sure I would feel safe flying a 4 rotor thing. Well, they're 8 but in 4 pairs on the same axis; a big enough bird or a hit on something hard enough would probably destroy 2 propellers at the same time, and the aircraft is rated for sustaining the loss of only one. Cool nonetheless.
https://jetson.com/jetson-one
https://www.youtube.com/watch?v=GAVwYIvmNEM
Very strange vibes indeed.
Deleted Comment
Curious how this is exempt from FAA regulations.
It looks neat and all, but it goes without saying... what could possibly go wrong?!
There are no licensing, knowledge, age, experience, or medical requirements for pilots of ultralights.
For the aircraft itself there are no certification standards, other than it has to meet the definition of a powered ultralight. That is:
Ultralights can only be flown between sunrise and sunset, unless they have an anti-collision light visible for 3 miles and are in uncontrolled airspace in which they can fly 30 minutes before sunrise to 30 minutes after sunset.They cannot be flown over any congested area or over an open air assembly of people.
I'm also curious how the FAA will determine max fuel capacity for an electric aircraft. Does battery weight count in the "empty" calculation? Is there an amp-hour-to-gallon average? Could I make a frame out of batteries to get "free weight" towards my design?
Deleted Comment
https://www.eaa.org/eaa/aviation-interests/ultralights/getti...
Deleted Comment
- in the cities of developed countries is forbidden to fly drones so big almost everywhere;
- in the same cities is forbidden to fly or landing ultralight plane ;
- this vehicle falls in both the previous categories, so that photos in urban areas are bullshit : you can't use that to go to the office and no cities will give the authorisation to rent that stuff as electric bike to everyone. That will never happen !
- How you can possibly guarantee the security with that kind of vehicle around, against criminal and terrorist ? Providing Stinger Missiles and Apache helicopters to the police ? Shooting down drones with machine guns inside the city in WWI style duels ? Oh, please ! :-)
- I imagine flock of this toys, piloted by drunken pilots, raining down Saturday night ! :-)
That admitting that this project is feasible: observing the photos of that vehicle, I can not see space for the batteries because, as described in the specs, it should float, so the landing support should be empty to guarantee buoyancy, they say batteries are far from the pilot to guarantee thermal protection, so they can't be under the seat and above the cabin should be the "ballistic parachute". So where are they ? In the pylons of the motors ? But in that case they won't be easily interchangeable are declared in the specs ! And that magic "hybrid technology" that should solve all the autonomy problems? No details at all , another red flag. So the photos of the "prototype" IMHO are more a Photoshop exercise than reality.
[0] https://www.youtube.com/watch?v=OYKs0k7LCM8
There was a push, years back, to not use the word, but eventually everyone caved.
This thing is just a beefcake of a quadcopter, sorta, so I'm not surprised to see that word thrown around.
Also, the company doesn't seem to use that word on the homepage, at least.
Deleted Comment
Its remote controlled as well as being locally piloted. Its a drone that happens to also have local controls.
“Every second of your flight is monitored by our highly trained and licensed primary and secondary flight controllers, with whom you’ll have radio communication who and can take over remote control of your aircraft at any time, if necessary.”
Deleted Comment
It looks like a (huge) drone so it's called a drone.
Too sad the marketing bullshit obfuscate what is the target here.
Seems like that is their target.
I thought that would be obvious… so side question: how would you have phrased it?
That being said, this is only aero efficiency. Once you start to add electric motor efficiency, things get interesting. To generate thrust with lower number of blades you need to have large torque torque to put into the prop , which means the motor has to be a low Kv (Kv = rpm/volt, and a low Kv means a high Kt where Kt = torque/amp), to keep the current lower to lessen electrical power losses. Or use a reduction gearbox. Both of the above necessitate a bigger package and more weight, which requires more thrust, and so on.
There is a place in this design space where having multiple rotors is actually more efficient for the overall flight envelope.
Smallish helicopters aren't that expensive. Maintenance and fuel are though. Going electric already helps with the fuel, going for many motors helps with the maintenance.