Aircraft

H3X claims it's tripled the power density of electric aircraft motors

H3X claims it's tripled the po...
The H3X electric motor design delivers up to three times the power per kilogram of existing motors on the market, offering serious weight savings for aircraft manufacturers
The H3X electric motor design delivers up to three times the power per kilogram of existing motors on the market, offering serious weight savings for aircraft manufacturers
View 9 Images
The H3X electric motor design delivers up to three times the power per kilogram of existing motors on the market, offering serious weight savings for aircraft manufacturers
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The H3X electric motor design delivers up to three times the power per kilogram of existing motors on the market, offering serious weight savings for aircraft manufacturers
Removable covers allow easy maintenance access on the rare occasion that components will need to be looked at
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Removable covers allow easy maintenance access on the rare occasion that components will need to be looked at
Integrating the inverters and other power electronics allows this design to run a single liquid-cooling jacket for both
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Integrating the inverters and other power electronics allows this design to run a single liquid-cooling jacket for both
The HPDM-250 will make 200 kW of continuous power at just 15 kg
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The HPDM-250 will make 200 kW of continuous power at just 15 kg
To use it in a conventional aircraft, you'll need to go for the slightly heavier 18-kg version with an integrated planetary gearbox, but power density is still extraordinary
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To use it in a conventional aircraft, you'll need to go for the slightly heavier 18-kg version with an integrated planetary gearbox, but power density is still extraordinary
Prototype testing is due to begin in Q2 next year
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Prototype testing is due to begin in Q2 next year
A single unit will deliver a hefty weight saving on a small electric plane, but things will really add up for multiple-rotor aircraft like eVTOLs
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A single unit will deliver a hefty weight saving on a small electric plane, but things will really add up for multiple-rotor aircraft like eVTOLs
The H3X motor will be premium-priced, but the weight savings, range benefits and payload boost should pay off quickly in a commercial application
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The H3X motor will be premium-priced, but the weight savings, range benefits and payload boost should pay off quickly in a commercial application
3D-printed copper coils play a key part in the monster power density of this motor
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3D-printed copper coils play a key part in the monster power density of this motor
View gallery - 9 images

If there's one major thing that's holding back an electric revolution in the aviation world, it's energy storage. But there are a ton of very clever people banging away at the problem of how to increase the energy density of batteries, and another growing faction working to make long-range, fast-fueling hydrogen-fuel-cell powertrains the standard for future flight.

Either way, it's going to happen in the coming decades, and one new company out of Minneapolis is turning its attention to the other critical element of the propulsion system. H3X Technologies is bursting out of the gate with an integrated electric motor design it says can deliver the same sustained power as some of the best motors on the market at a third or less of the total weight.

Weight, of course, is a big deal in aviation – and that goes double for electric aircraft. Every pound carried skyward represents a pound less payload you can carry, a reduction in the range you'll get from your battery or hydrogen tank, and ultimately a loss of money for the owner.

With small to medium electric planes beginning to go into commercial service, and the long-promised rise of the eVTOL air taxi segment forever just around the corner, H3X sees big opportunities ahead for a monster weight-saver like its HPDM-250 motor.

H3X HPDM 250 electric aircraft motor design

The first version will weigh 15 kg (33 lb) and make 200 kW of continuous power, peaking at up to 250 kW. That's 13.3 continuous kilowatts per kilogram, an extraordinary power density. For comparison, the Magnax axial flux motor we covered in 2018 boasts 15 kW/kg – but that's peak power; its continuous power density is more like 7.5 kW/kg.

And that in itself is absolutely exceptional. The motor used on the world's first commercial electric aircraft flight last year by Harbour Air was a Magnix Magni500 – yes, there are competing electric motor companies called Magnix and Magnax – and that thing's power density is more like 4.2 kW/kg.

What's more, neither of the above motors have an inverter built in, so there's some extra weight you've got to carry – 12 kg (33 lb) in the case of the Magnix drive system. The H3X design has its inverter integrated into its hexagonal prism body.

The motor's highest efficiency is at 20,000 rpm, which is way faster than you'd spin a propeller, so H3X can also fit it with an integrated planetary gearbox with a 4:1 reduction ratio, incurring a weight cost of just three additional kilos (6.6 lb). H3X founder and CEO Jason Sylvestre tells us the team could've designed the motor to spin slower and eliminated the gearbox, but the overall efficiency and power density would've suffered.

A single unit will deliver a hefty weight saving on a small electric plane, but things will really add up for multiple-rotor aircraft like eVTOLs
A single unit will deliver a hefty weight saving on a small electric plane, but things will really add up for multiple-rotor aircraft like eVTOLs

The H3X HPDM-250's peak combined efficiency between the motor, gearbox and inverter in this configuration – the one most likely to be used aboard an electric aircraft – is 92.9 percent. That's pretty much bang on the energy efficiency of the Magni500, just with vastly higher power output per unit of weight. Its continuous power density with the gearbox on board is 11.1 kW/kg, still well clear of the competition.

How has this Minneapolis startup team achieved such a remarkable leap in power density? Sylvestre tells us it's a combination of factors all adding up.

"The HPDM-250 has been designed to push the limits of performance while minimizing system mass," he says. "It is the product of patent pending innovation in multiple areas and features the highest level of integration on the market. This includes electromagnetics optimization, additive manufacturing, advanced materials, and high-frequency SiC power electronics.

"Two innovations are worth highlighting – We use a single, synergistic cooling jacket to simultaneously cool both the power electronics and motor. This integration reduces system mass and volume. Additive manufactured copper stator coils are used to increase copper fill factor and improve continuous current density capability. This is a new technology that has the potential to revolutionize the motor manufacturing industry as it offers faster development, better performance, and greater design flexibility."

Those 3D-printed copper stator coils not only allow H3X to fit more copper into a smaller space, they help a lot with cooling, allowing the HPDM-250 to run closer to its peak power without generating unmanageable amounts of heat. And Sylvestre says additive manufacturing means that this motor will be quick to prototype, iterate, scale to different sizes and power levels, and adjust to customer requirements.

3D-printed copper coils play a key part in the monster power density of this motor
3D-printed copper coils play a key part in the monster power density of this motor

Sylvestre tells us that even though the components are tightly packed in the motor design, its six-cover shell makes for easy access on the rare occasion you'll need to open it up.

Replacing a roughly 50-kg (110-lb) motor with an 18-kg (40-lb) one will deliver a tasty little weight dividend on a single-prop plane, but the benefits will scale up the more motors your design uses. Sylvestre sees this design as offering major payload, cost and range advantages to eVTOL air taxis that typically use upwards of six props. But H3X has its sights set on bigger targets.

"In the next five years, we're going to see those eVTOLs and small electric aircraft," says Sylvestre. "But by around 2030, we'll start to see electrification of large commercial aircraft. That's really what you want to go after. Aircraft around the size of a Boeing 737, those account for around 50 percent of all the greenhouse gas emissions in the aircraft sector. An aircraft that uses distributed propulsion with multiple 250-kW motors, maybe 16 or so, along each wing. You can imagine the weight of those will add up, and that's where a motor like ours could make a huge difference."

As always, extraordinary claims require extraordinary evidence, so we look forward to hearing how the prototype performs.

"We're in the process of prototyping it right now," says Sylvestre. "We should be testing it by Q2 of next year. In terms of the business, we're looking to get letters of intent from potential customers, and partner with early investors to expand H3X. We've been operating very much in stealth mode."

One to keep an eye on.

Source: H3X

View gallery - 9 images
26 comments
John-Paul Hunt
Mmmhhhmm. Adds starlink small nano antenna to aircraft like on my car and smartphone/laptop as all capable cable repairman can pops.
Daishi
When humans still believed in the geocentric model of the solar system they used the ptolemaic system to accurately predict the movement of the planets. When the heliocentric model was first proposed it was initially less accurate than the ptolemaic system at predicting movement because it was less refined. Outside of an early brief stint in the auto industry most electric motors were used in fixed commercial setting until semi-recently with electric motors becoming more common in mobile applications and transport and most R&D has been focused on fossil fuel based motors. Even though electric motors are comparatively simple it's nice to see there is still room for innovation and improvement for mobile applications.
Lukemaj
So many questions after just renders and few figures. 1) How is it cooled? It mention that copper layout allows for better heat management but over time it need to be transferred out. back connections might suggest liquid, than if so is mass of coolant, pump and heat exchange included? 2) I am happy that it looks like ignorance to typical design of electric motors as that might be part of new fresh approach to problem, however there are reasons for standards in cases for electric motors and not as much with size or heat dissipating fins outside but mostly with the way motor should and can be mounted, now on renders there is no single attachment point for this motor, well there is shaft for gear box/propeller, but no way to fix other end to frame. And that is bringing further doubts about other things which are working excellently for this motor on paper and maybe in simulations, but until full real build proves it hard to judge...
Worzel
''Aircraft around the size of a Boeing 737, those account for around 50 percent of all the greenhouse gas emissions in the aircraft sector.''......... All electric motors do, if replacing fossil fuel engines, is to transfer the emissions to the power station. So when transmission losses a considered, they exacerbate the problem. However, as CO2 and water are the main emissions there is no problem. CO2 = Global Warming is political myth. The positive side is that passengers are not flying in a massive fuel tank and are less likely to be toasted in the event of a bad landing. Whether the batteries will have a similar effect remains to be seen.
michael_dowling
I don't see the point of getting excited over this development. If you are still using batteries,a lighter motor will only give another few miles of range,but the total range will still be pathetic compared with ICE powered flight. The future is in fuel cell technology,which has far more power density than batteries,and fast refueling times. There are already prototypes in testing: https://newatlas.com/aircraft/zeroavia-first-commercial-scale-hydrogen-fuel-cell-electric-flight/
buzzclick
H3X's development is another exciting step towards e-flight efficiency, even though it's performance projections still have to be proven to justify the optimism. I would imagine that the cooling setup would need to be modulated since the temperatures at ground level would require more, as opposed to the colder temperatures in flight.

The visual in my head of a Boeing 737-sized plane with 16 motors is not appealing. In fact quite ugly.
Karmudjun
Still prototyping, I'll wait for the results of test flights before I believe this hype. Looks good on the screen. Just like 'global warming is a political myth' looks good on the screen. I believe what I know and I see - not just read on a screen. Great article Loz, but there are other questions prototyping can't answer like cost, duty cycle, maintenance issues, etc. Real world issues where things like hypercapnia apply!
Expanded Viewpoint
You CANNOT cheat Mother Nature out of her due!! Until someone comes up with a way to generate electricity without impacting the planet in some way, then all of this talk about the joys and benefits of converting over to electrical power for transportation of goods and people, is just so much hot air!! Evidently, the number of people who can think logically and in a straight line longer than to just the end of their own nose, is quite small indeed!!

Randy
John Schubert
Others here have commented on the many yet-to-be-proven electrical and thermal engineering aspects of this concept. (It doesn't appear that they have a working prototype). I'll comment on a more mundane, but equally important, aspect: the required gearbox. Aircraft geared engines were rare, and not all that successful, until Rotax came along. Other brands had reliability problems. Rotax has refined the concept, but for a gear reduction of about 1:2.3. The electric engine in this article would require a reduction of close to 1:10. Doing that will take a lot of engineering. Designing a certification standard, and getting it adopted by the Federal Aviation Administration, will take a lot of engineering and a lot of bureaucratic maneuvering.
Edward Vix
France has been happily running on nuclear fission power for decades. Way ahead of the rest of us as they often are.