Before electrification, short-hop aviation relied on combustion engines and complex transmissions that were noisy, maintenance-intensive, and inefficient at low altitude. After the shift to distributed electric propulsion, eVTOL aircraft aim for fewer moving parts, higher torque at low RPM, and improved reliability from redundant motor arrays. Rare earth-enabled permanent magnets and optical materials underpin this transition by boosting motor power density, stabilizing performance at temperature, and supporting sensing and displays. This article explores where rare earths sit in the system, how they improve efficiency and safety, which innovators brought key breakthroughs, and where supply-chain risks lie.
Table of Contents
How did eVTOL aircraft change urban air mobility—and why do rare earths matter?
Helicopters once dominated short-hop aviation, but their combustion engines and gear-driven transmissions made them noisy, maintenance-heavy, and fuel-hungry. Distributed electric propulsion changed that model, replacing complex mechanics with compact motor arrays that offer higher torque, lower noise, and greater reliability.
Modern eVTOL aircraft use multiple electric motors spread across the airframe, each with fewer moving parts and higher reliability than traditional helicopter drivetrains. This design depends heavily on rare earth elements—the special metals that make compact, powerful electric motors possible. Rare earth permanent magnets enable motors with five times the power density of conventional designs (opens in a new tab), while rare earth optical materials support the advanced sensors and displays these aircraft need to navigate safely.
The transition matters because eVTOL aircraft promise to move people above traffic jams without the noise and emissions of helicopters. But this vision depends on a supply chain that starts in rare earth mines and ends in precision-engineered motor assemblies. Understanding where these materials come from and how they work helps explain both the promise and the challenges facing urban air mobility.
Inside the eVTOL Motor: Where Rare Earths Do the Work
Which rare earth elements are used in eVTOL motors?
The most important rare earths for eVTOL propulsion are neodymium and praseodymium. These elements form the core of neodymium-iron-boron (NdFeB) permanent magnets that power most eVTOL motors. NdFeB magnets deliver the highest energy product of any permanent magnet material (opens in a new tab), meaning they create strong magnetic fields in small packages.
Engineers add small amounts of dysprosium or terbium to these magnets when motors will face high temperatures. These heavy rare earths increase coercivity—the magnet's resistance to losing its magnetism when heated (opens in a new tab). For the hottest applications, manufacturers might use samarium-cobalt magnets instead. SmCo magnets maintain their strength up to 350°C (opens in a new tab), though they're heavier and more expensive than NdFeB.
Beyond motors, rare earths appear throughout eVTOL systems. Yttrium, cerium, europium, and terbium create the phosphors that make LED cockpit displays bright and efficient. These phosphor materials convert blue LED light into the full color spectrum pilots need. Terbium also appears in magneto-optical isolators that protect laser sensors from reflected light. Terbium gallium garnet crystals provide this isolation function better than any alternative material.
How rare earths strengthen eVTOL motor performance
The magic happens at the atomic level. Rare earth atoms have unpaired electrons in their inner shells that create strong, permanent magnetic moments. When billions of these atoms align in a magnet, they generate powerful magnetic fields that don't fade over time.
In an eVTOL motor, these permanent magnets sit in the rotor—the spinning part. Electric current flows through copper windings in the stationary stator, creating a rotating magnetic field. This field pushes and pulls on the permanent magnets, making the rotor spin. The stronger the permanent magnets, the more torque the motor produces for its size and weight.
Siemens demonstrated this principle with a 260-kilowatt aircraft motor weighing just 50 kilograms—about five times the power-to-weight ratio of comparable combustion engines. This breakthrough came from using NdFeB magnets arranged in special patterns that concentrate the magnetic field where it's needed most.
Temperature management remains critical. Standard NdFeB magnets start losing strength above 80°C and can permanently demagnetize above 150°C. That's why engineers add dysprosium or terbium—these elements shift the temperature limits higher, though each percent added increases cost substantially. Some designs use different magnet types in different zones, with SmCo in the hottest areas and NdFeB where cooling keeps temperatures moderate.
Journey from Mine to Product
Supply chain steps
The path from underground ore to spinning rotor involves multiple specialized steps, each with its own challenges and bottlenecks.
Mining operations extract rare earth ores like bastnäsite and monazite from hard rock deposits, or ionic clays in southern China. These ores contain only 0.1% to 10% rare earth oxides by weight, requiring massive volumes to produce usable amounts. Miners crush and concentrate the ore, then ship it to separation facilities.
Chemical separation might be the most complex step. Rare earth elements are chemically similar, making them hard to separate. Facilities use hundreds of extraction stages with organic solvents to isolate individual elements. China controls about 85% of global separation capacity, though new facilities are under construction in the United States and Europe.
Once separated, rare earth oxides get converted to metals through electrolysis or metallothermic reduction. Magnet manufacturers then melt these metals with iron and boron, creating an alloy powder. They press this powder in strong magnetic fields to align the particles, then sinter it at high temperature to create solid magnets. Final steps include machining to precise dimensions, coating to prevent corrosion, and magnetizing to full strength.
Motor manufacturers receive these finished magnets and carefully install them in rotors. The magnets must be positioned precisely—sometimes in complex Halbach arrays that focus the magnetic field. Any misalignment reduces efficiency and creates unwanted vibration.
Typical chokepoints
The rarest bottleneck isn't the rare earths themselves, but the know-how to process them efficiently. Converting raw ore to separated oxides requires about 50 different chemical processes, and few companies outside China have mastered the full sequence.
Heavy rare-earths like dysprosium and terbium face particular supply constraints. These elements come mainly from ionic clay deposits found almost exclusively in southern China and Myanmar. Unlike light rare earths, which appear in deposits worldwide, heavy rare earths have few alternative sources under development.
Magnet manufacturing represents another chokepoint. Making aerospace-grade NdFeB magnets requires precise control over grain size and boundaries—the tiny crystalline regions that determine magnetic properties. The grain boundary diffusion process that adds dysprosium only where needed took decades to perfect and remains concentrated in a handful of facilities.
Statistics & Societal Impact between eVTOLs and Rare Earths
Quantitative snapshot
The numbers reveal both progress and challenges for eVTOL deployment. China processes approximately 90% of the world's rare earth elements, creating a supply chain vulnerability for Western eVTOL manufacturers. This concentration extends to magnet production, where Chinese companies dominate even when using rare earths mined elsewhere.
Certification progress shows the industry approaching commercial operation. Joby Aviation received its Part 135 air carrier certificate from the FAA in 2022, allowing it to operate as an air taxi service once its aircraft receives type certification. Archer followed with its Part 135 certificate in 2024. Meanwhile, EHang secured the world's first eVTOL type certificate from Chinese regulators in October 2023, marking a regulatory milestone.
Material intensity offers another key metric. Electric vehicle traction motors typically use between 0.5 and 2.5 kilograms of NdFeB magnets. Since eVTOL aircraft use multiple high-power motors—Joby's design has six, Lilium's has 36 smaller ones—total magnet content could exceed typical EV levels, especially when using high-temperature grades with added dysprosium.
Downstream effects
The efficiency gains from rare earth magnets cascade through the entire aircraft design. Higher motor efficiency means less heat to manage, smaller cooling systems, and more battery energy available for actual flight. NASA studies show that distributed electric propulsion can achieve 20% better efficiency than traditional helicopter designs while reducing noise by spreading thrust across multiple smaller rotors.
This efficiency translates directly to passenger experience and operational economics. Quieter operation—enabled by precise motor control and optimized rotor speeds—makes landing sites more acceptable in urban areas. Better reliability from simpler mechanical systems with fewer failure modes could reduce maintenance costs by 30% compared to helicopters.
The safety implications are equally important. Multiple independent motors provide redundancy—if one fails, the others can compensate. Rare earth magnets enable this redundancy without excessive weight penalties because each motor can be compact yet powerful. The instant torque response of permanent magnet motors also improves flight control precision during critical phases like transition from vertical to forward flight.
Innovators & History
Key breakthroughs
The foundation for today's eVTOL motors began in university laboratories decades ago. Karl Strnat created the first samarium-cobalt magnets at Wright-Patterson Air Force Base in 1966, proving rare earth elements could create permanent magnets far stronger than traditional ferrite or AlNiCo types.
The real revolution came in 1984 when two teams independently discovered neodymium-iron-boron magnets. Masato Sagawa at Sumitomo Special Metals in Japan developed the sintered version, while John Croat at General Motors created a rapid-solidification process for bonded magnets. These NdFeB magnets delivered twice the energy product of SmCo at lower cost, though they needed protective coatings and couldn't handle high temperatures without modification.
Electric aviation pioneers recognized this potential early. Siemens flew its breakthrough 260-kilowatt motor in 2016, achieving power density that made electric flight practical for the first time. More recently, Lilium demonstrated that dozens of small ducted fans with permanent magnet motors could provide both vertical lift and efficient forward flight.
From lab to product
Moving from laboratory curiosity to aerospace component required solving multiple challenges. Early NdFeB magnets corroded easily and lost magnetism at modest temperatures. Researchers developed multi-layer coatings and grain boundary engineering techniques through the 2000s and 2010s.
The grain boundary diffusion process, perfected by Japanese researchers, proved especially important. By diffusing heavy rare earths only into the grain boundaries rather than throughout the magnet, manufacturers could achieve high-temperature performance using 70% less dysprosium. This technique made aerospace applications economically feasible.
Motor designers also innovated around the magnets. Halbach arrays—special arrangements where magnets reinforce the field on one side while canceling it on the other—increased motor efficiency by 25%. Axial flux designs, where the magnetic field runs parallel to the motor shaft rather than perpendicular, achieved even higher power density by shortening the magnetic path length.
Why It Matters Now
Current drivers
Several trends converge to make rare earth availability critical for eVTOL success right now. Battery energy density has improved enough to enable useful flight times. The FAA and EASA have published certification pathways for eVTOL aircraft, giving manufacturers clear targets. Cities from Los Angeles to Paris are planning vertiport infrastructure.
But motors remain the limiting factor for many designs. While batteries will improve gradually, motor technology must deliver maximum performance today. The Department of Energy identifies permanent magnet motors as essential for transportation electrification, with aerospace applications requiring the highest performance grades.
Investment flows reflect this importance. Venture capital has poured billions into eVTOL companies, but smart money also backs materials plays. MP Materials, America's only rare earth mining and processing company, has received Department of Defense funding to build magnet manufacturing capability. Similar initiatives in Europe and Japan aim to reduce dependence on Chinese processing.
Security & policy context
The concentration of rare earth processing in China creates strategic vulnerabilities that governments can't ignore. China added certain rare earth magnet production technologies to its export control list in December 2023, signaling potential supply restrictions.
Western responses blend industrial policy with technology development. The European Union's Critical Raw Materials Act sets targets for domestic processing and recycling. The U.S. Department of Defense has funded not just MP Materials but also E-VAC Magnetics to demonstrate recycled rare earth magnet production.
Recycling offers a partial solution. Companies like HyProMag in the UK use hydrogen processing to recover rare earths from old magnets, while Urban Mining Company in Texas extracts rare earths from electronic waste (opens in a new tab). These sources can't replace primary mining but could buffer supply shocks.
Future Outlook
Materials & design trends
Engineers are finding creative ways to stretch rare earth supplies without sacrificing performance. Core-shell magnet structures put expensive heavy rare earths only in the outer shell where temperature resistance matters most. Some designs use SmCo magnets in the hottest zones and NdFeB elsewhere, optimizing material use.
Alternative motor designs might reduce rare earth dependence. Switched reluctance motors use no permanent magnets, generating magnetic fields entirely from electric current. They're heavier and less efficient than permanent magnet motors, but could serve as backup options if rare earth supplies tighten.
Manufacturing advances continue to improve material efficiency. Additive manufacturing might enable complex magnet shapes that waste less material. Better recycling technology could recover 95% of rare earths from end-of-life motors, though collection logistics remain challenging for dispersed products like aircraft.
5-10 year scenario: What rare earth investors should consider
The next decade will test whether rare earth supplies can match eVTOL ambitions. If certification proceeds smoothly and early commercial operations succeed, hundreds of aircraft could enter service by 2030. Each aircraft might need 10-50 kilograms of rare earth magnets, depending on design choices.
The International Energy Agency projects that rare earth demand for clean energy technologies will triple by 2030 (opens in a new tab). eVTOL aircraft represent a small but high-value segment of this demand. Their aerospace requirements for quality and traceability might command premium prices, ensuring supply even if other sectors face shortages.
New mining projects could ease supply pressure by mid-decade. The USGS identifies several promising deposits under development in Australia, Canada, and the United States. But these projects face long lead times and environmental challenges
Conclusion
Rare earth elements are fundamental enablers of eVTOL aircraft, providing the high-performance magnets and optical materials necessary for efficient electric propulsion and advanced avionics. While supply chain concentration poses risks, ongoing efforts in recycling, alternative processing, and material innovation offer pathways to sustainable scaling. As urban air mobility moves toward commercial deployment, securing stable rare earth supplies while advancing technical efficiency will remain critical to realizing the promise of quiet, clean, vertical flight.
FAQs
Do all eVTOL aircraft require rare earth magnets in their propulsion systems?
While most high power-density electric propulsion systems use NdFeB or SmCo permanent magnets, some designs can use induction or switched-reluctance motors to avoid rare earths at the cost of efficiency and power density. For eVTOLs constrained by weight and thermal margins, permanent magnets remain the prevalent choice.
How much rare earth material might an eVTOL aircraft use?
Estimates depend on architecture, motor count, and temperature strategy. As a proxy, high-performance EVs use roughly 0.5–2.5 kg of NdFeB magnets per vehicle. An eVTOL with multiple high-power motors could fall within or above that range, especially if higher-coercivity grades with Dy/Tb are used.
Why would an engineer choose SmCo over NdFeB in an eVTOL motor?
SmCo offers better intrinsic temperature stability and corrosion resistance, reducing risk of demagnetization in hot zones or under fault conditions, albeit with lower maximum energy product and higher cost. Engineers may deploy SmCo in thermally stressed regions and NdFeB elsewhere to balance performance.
Are there supply-chain efforts to reduce reliance on Chinese processing for eVTOL-critical rare earths?
Yes. The U.S., E.U., and allies are investing in separation, alloying, and magnet manufacturing capacity, alongside recycling, aiming to diversify sources and shorten logistics chains relevant to aerospace programs.
Beyond propulsion, where else do rare earths show up in eVTOL aircraft?
Rare earths appear in optical components (Nd:YAG lasers, TGG isolators), LED/display phosphors (Y, Ce, Eu, Tb), and manufacturing consumables like cerium oxide polishing compounds for sensors and transparencies. These uses support navigation, human–machine interfaces, and production quality.
