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electric aviation propulsion systems 2

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Clyde38

Clyde38

Electrical
Oct 31, 2003
533
Does anyone know the state of the industry for aircraft electric motor development, globally? I'm referring to full size aircraft, not models or small drones. I know that the internet has information, as an example, Rolls-Royce set out three years ago to build the world’s fastest electric aircraft—teaming up with two U.K. firms: the Daimler-owned automotive supplier YASA ( and aerospace engineering startup Electroflight. The aircraft was propelled on its record breaking runs by a 400kW (500+hp) electric powertrain. I'm trying to find out what the state of the art in this field is and who the manufacturers are. Thanks for your help.

Clyde Hancock
Design & analysis of electric motors and generators
 
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Thanks WindWright and LionelHutz however, I would like to focus on the electric powertrain used for the aircraft (axial gap, radial gap, PM, induction, SyncR, etc.)and the current existing manufacturers of these motors. Also, the advantages and disadvantages of each technology.

Clyde Hancock
Design & analysis of electric motors and generators
 
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magniX motor supplier cited at the link for Harbour Air has pictures and specs on the website, but other than s reference to the components being water cooled, construction is not published.
 
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Clyde said:
Thanks WindWright and LionelHutz however, I would like to focus on the electric powertrain used for the aircraft (axial gap, radial gap, PM, induction, SyncR, etc.)and the current existing manufacturers of these motors. Also, the advantages and disadvantages of each technology.
Click to expand...

You're very welcome Clyde, but that looks like research you should be doing, not us. If you didn't know about the Eviation aircraft or the Magnix until we answered you, then clearly you haven't spent much time on the subject, have you?

Point of order: I have spent too much time in the past few days cleaning up forum messes and vague posts based on inadequate research. That's not your fault, but it's tedious. Why am I here? If you have sincerely done some research on the matter, then please bring it up and engage in a deeper discussion. That's what we'd all appreciate and enjoy more. More than "tell me what you know".

We are also being besieged by bots that somehow ask questions that look real but are actually generated by an algorithm. It would help if you wrote some of your own thoughts down so that we can be sure.
 
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Thanks WindWright. I agree, I should have provided more background. I have done quite a bit of on line research. I was aware of Eviation and Magnix as well as Magnicall, Rotex electric, T-Motor, Safran, Rolls Royce-Siemens, Archer, MGM Compro, and several more. The issue that I'm facing is that they don't go into much depth about the technology being implemented. I have found that Rolls Royce is using an axial gap BLDC (YASA, two in tandem), aside from this the information is not readily available. I'm reading EVTOL in an effort to gain some insight. I have reviewed several papers ie; ELECTRIC VTOL CONFIGURATIONS, A NASA PERSPECTIVE ON ELECTRIC PROPULSION TECHNOLOGIES FOR COMMERCIAL AVIATION, IEEE, and more. Some manufacturers offer data sheets however, I feel that they are somewhat driven by marketing and they do not offer specifics. What I'm interested in is the technologies and the pros and cons of each approach. I find Keith's comments about superconducting motors and links very helpful. I design electric motors and I would like to be prepared should I have to design motors for aviation propulsion applications. I have designed motors for radio controlled quad copters however the scale is much different from passenger aircraft.

Clyde Hancock
Design & analysis of electric motors and generators
 
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The manufacturers will be keeping their design details confidential, for obvious reasons.
 
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LOL, that makes no sense. If the manufacturers are keeping it a secret then we won't know anything the manufacturer hasn't shared either unless we worked for the manufacturer and in that case we'd be keeping it a secret.
 
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Yeah, I don't expect anyone to divulge proprietary information. My thought was that there should certainly be a lot more information within the community then what I personally have. I believe that there is a wealth of knowledge within this community. For instance, Keith's feedback was beneficial to me. I guess if you feel that I am wasting yours and my time then you could report this post as inappropriate and have it deleted.

Clyde Hancock
Design & analysis of electric motors and generators
 
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Thank you Clyde! I am really happy you are a real person! [smile]

I've seen similar things develop in electric aviation, even though I'm not tracking this subject as closely as you seem to be. Electric "traction" motor technology has a lot of varieties; there's no clear winner yet in any given application. You also can't separate the motor from the control any more, and the architecture of the motor drive unit is probably the most tightly held secret. It wouldn't surprise me at all if the Eviation engineers are still NOT permitted to open the drive unit boxes yet, even though eventually a certification spec will have to be generated.

If you want to get a flavour of the various technologies that are being used in traction motors, you can always look deeply into the automotive sector, where a lot more information is available. Lots of well documented EV automobiles with service and maintenance manuals, troubleshooting guides, and even DIY modifiers taking them apart to re-purpose the drivetrain for conventional auto conversion projects. They crack the CANBUS, make custom interfaces, integrate the chassis and presto they have something like an RX-7 body with a Tesla drivetrain. Some of it is just to climb the mountain "because it's there" but it also reveals a state of the art at multiple levels.

I am not convinced that the technology being used in electric aviation is any different from the technology in EV autos, although Itsmoked's hint about superconductors makes me question that. The big players could deal with that complexity. Looking at the other end of the scale, there are a lot of small start-ups developing electric propulsion for aircraft, and not all of them are just scaling up toy drones to a size big enough to carry a person. The scaled-up drone messaging seems to come from hobbyists who have no idea what aircraft certification is like. There are some notable exceptions from developers like Ampaire, Lilium, and Eviation that seem to have both funding and technical depth to get somewhere with their concepts. However I don't think that these particular aircraft are benefiting from radical technical leaps.
They seem to be integrating existing technology into a form that hasn't been tried but now seems to be possible.
 
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Two things to add.

Part of the general motivation and embracing for superconducting motors in aircraft is the already formalized, high quality, mature, proven maintenance system. The expectation is that the newly applied SC equipment will be ably monitored, maintained, and understood by the companies using it. This is unlike probably any other application field. This makes potential SC motor developers much more interested in proceeding than probably any other field where there isn't enough motivation for SC systems or there's maybe huge motivation but far too few needed to justify proceeding.


I saw on the front page of some magazine, about 2 years ago, a Siemens superconducting turbo prop(?) in a test jig in a massive, complex, development lab fully decked out with a bunch of workers around it. The picture was identified as being a SC aircraft motor under development for airliners. It looked highly developed and was listed as having a jaw-dropping multi-megawatt output. Probably why Rolls-Royce bought the entire division and why that picture seems to have disappeared from the planet.

Keith Cress
kcress -
 
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Yes, the "electrical" efficiency of superconducting motor will be significantly (?) higher higher than that of a conventional electrical motor. But the system efficiency? This is where a sub-zero (C) superconductor would really, really shine. Suck up the normal motor losses until above the freezing level and then continue on using an ambiantly cooled superconductor. But a conventional superconductor that requires either lots of energy on board or lots of energy brought onboard in the form of highly compressed gases seems to be missing something...

I’ll see your silver lining and raise you two black clouds. - Protection Operations
 
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Aren't motor efficiencies already rather high? I am uncertain that superconducting motors would have a large efficiency advantage. Battery storage is still a factor of 10X behind on mass and volume density relative to fuels/combustion so it's not possible to make up for that by just removing resistance losses.

What superconducting does help is lowering the mass of the motor as smaller conductors can be used, but then that brings up the problem that the forces on the conductors remain the same with possibly less strength due to less section. Superconductivity must help with MRIs where the magnetic density needs to be high and the smaller conductors allow the windings to be packed in around the core but there's no weight disadvantage.

Then it needs a container for the liquified gas coolant, so that offsets the weight reduction. And there's the question of what to do with the losses in the cables from the batteries to the motors.
 
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Thankyou to everyone for your responses. They were all helpful and informative. I'm no expert so I'm indeed fortunate to have access to a community of experts that are willing to share valuable information.

Clyde Hancock
Design & analysis of electric motors and generators
 
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