If there is anything important that is preventing an electrical revolution in the aviation world, it is energy storage. But there are a ton of very smart people battling the problem of how to increase the energy density of batteries, and another growing faction working to make fuel long-range and fast. hydrogen fuel cell power trains the standard for future flights.
Anyway, this will happen in the coming decades, and a new Minneapolis company is turning its attention to the other critical element of the propulsion system. H3X Technologies it is exploding out of the gate with an integrated electric motor design that says it can deliver the same sustained energy as some of the best engines on the market at a third or less of total weight.
Weight, of course, is big business in aviation – and that’s twice as much for electric aircraft. Each pound transported to heaven represents one pound less payload you can carry, a reduction in the range you will get from your battery or hydrogen tank and, ultimately, a loss of money for the owner.
With small and medium-sized electric planes starting to enter commercial service, and the promised increase in the eVTOL air taxi segment Forever around the corner, the H3X sees great opportunities ahead for a weight-saving monster like its HPDM-250 engine.
H3X HPDM 250 aircraft electric motor design
The first version will weigh 15 kg (33 lb) and will produce 200 kW of continuous power, with a peak of up to 250 kW. That’s 13.3 continuous kilowatts per kilogram, an extraordinary power density. For comparison, the Magnax axial flow motor we covered in 2018 it has 15 kW / kg – but it is the peak power; its continuous power density is closer to 7.5 kW / kg.
And that in itself is absolutely exceptional. The engine used in the world’s first commercial electric aircraft flight last year by ZeroAvia was a Magnix Magni500 – yes, there are competing electric motor companies called Magnix and Magnax – and the power density of this thing is more like 4.2 kW / kg.
In addition, none of the above motors has a built-in drive, so there is some extra weight that you need to carry – 12 kg (33 lb) in the case of the Magnix drive system. The design of the H3X has its inverter integrated into the body of the hexagonal prism.
The highest engine efficiency is 20,000 rpm, which is much faster than you would spin a propeller, so the H3X can also equip you with an integrated planetary gearbox with a 4: 1 reduction ratio, incurring a weight cost of just three additional pounds (6.6 lb). H3X founder and CEO Jason Sylvestre told us that the team could have designed the engine to spin more slowly and eliminated the gearbox, but the overall efficiency and power density would have suffered.
The combined maximum efficiency of the H3X HPDM-250 between the engine, gearbox and inverter in this configuration – the one that is likely to be used on board an electric aircraft – is 92.9 percent. This is very good for the Magni500’s energy efficiency, only with a much higher power per unit weight. Its density of continuous power with the gearbox on board is 11.1 kW / kg, still far from the competition.
How did this Minneapolis startup team achieve such a remarkable jump in energy density? Sylvestre tells us that it is a combination of factors that add up.
“The HPDM-250 was designed to push performance limits while minimizing system mass,” he says. “It is the innovation product with patent pending in several areas and has the highest level of integration in the market. This includes electromagnetic 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 the power electronics and the engine. This integration reduces the mass and volume of the system. Additive manufactured copper stator coils are used to increase the fill factor copper and improve the density of direct current capacity. This is a new technology that has the potential to revolutionize the engine manufacturing industry as it offers faster development, better performance and greater design flexibility. “
These 3D printed copper stator coils not only allow the H3X to put more copper in a smaller space, but also help a lot in cooling, allowing the HPDM-250 to work closer to its peak power without generating uncontrollable amounts of heat. And Sylvestre says that additive manufacturing means that this engine will be quick to prototype, iterate, scale to different sizes and power levels and adjust to customer requirements.
Sylvestre tells us that, although the components are well packaged in the engine design, its six-cover casing makes it easy to access on the rare occasions when you need to open it.
Replacing an approximately 50 kg (110 lb) engine with an 18 kg (40 lb) engine will result in a small tasty weight dividend on a single propeller plane, but the benefits will increase the more engines your project uses. Sylvestre sees this project as a major payload, cost and reach advantage for eVTOL air taxis that normally use more than six propellers. But the H3X has its eyes set on bigger targets.
“In the next five years, we will see these eVTOLs and small electric aircraft,” says Sylvestre. “But around 2030, we will begin to see the electrification of large commercial aircraft. This is really what you want to pursue. Aircraft the size of a Boeing 737 are responsible for about 50 percent of all emissions. greenhouse gases in the aircraft industry. An aircraft that uses distributed propulsion with several 250 kW engines, maybe 16 or more, along each wing. You can imagine their weight will add up, and that’s where an engine like the ours can make a big difference. “
As always, extraordinary claims require extraordinary evidence, so we look forward to hearing how the prototype works.
“We are in the prototyping process now,” says Sylvestre. “We should test it by the second quarter of next year. In terms of business, we are looking to receive letters of intent from potential customers and partner with early investors to expand H3X. We have been operating a lot in stealth mode.”
One to keep an eye on.