A Detailed Axial Flux Motor Performance and Efficiency Showdown

Radial vs. Axial Flux showdown. We compare torque density, efficiency maps, and thermal performance to see why axial flux technology is winning the EV race.

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A Detailed Axial Flux Motor Performance and Efficiency Showdown

In the race for electric propulsion dominance, the motor is the heartbeat. For decades, radial flux motors have been the industry standard, they are reliable, familiar, and easy to manufacture. But as electric vehicles (EVs), electric aviation, and high-performance marine vessels demand more power in smaller packages, a new champion has entered the ring.

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This is the ultimate showdown: Axial Flux vs. Radial Flux.

In this technical deep dive, we’re stripping away the marketing fluff to look at the raw performance metrics. We’ll analyze torque density, efficiency maps, and thermal management to understand why axial flux technology (and specifically, Beyond Motors’ architecture) is rewriting the rules of electric propulsion.

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Round 1: Torque Density (The heavy lifter)

Torque density is the "pound-for-pound" strength of a motor. In this category, the fundamental geometry of axial flux motors gives them an unfair advantage.

• Radial Flux: In a traditional radial motor, the magnetic flux travels perpendicularly to the axis of rotation. The torque generation is limited by the rotor's diameter, which is often constrained inside the stator.
• Axial Flux: The magnetic flux travels parallel to the axis. This allows for a larger rotor diameter within the same overall volume. Since torque is a function of the radius at which force is applied, this geometry naturally produces significantly higher torque.

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The Verdict:

Axial flux motors typically deliver 30-40% higher torque density than comparable radial flux designs. For high-load applications like heavy-duty EVs or propeller aircraft, this means you can move heavier loads without increasing the motor's weight.

Beyond Motors Advantage: Our AXM Series pushes this further with a stackable design. By double or triple-stacking the motors, we multiply torque output without expanding the motor's diameter, a feat virtually impossible with radial geometry.

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Round 2: Power-to-Weight Ratio (The speedster)

If torque is strength, power density is athleticism. For aviation and high-performance automotive sectors, every gram matters.

• Radial Flux: To get more power, you usually need to make the motor longer or wider, adding significant iron and copper weight. Most high-end radial motors struggle to break past 4-5 kW/kg.
• Axial Flux: The "pancake" shape requires less core material (iron) to carry the magnetic flux. Less iron means less weight. Leading axial flux designs can achieve power densities exceeding 10 kW/kg, with some cutting-edge iterations pushing even higher.

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The Verdict:

Axial flux wins by a landslide. The lightweight, compact nature of these motors makes them the only viable option for electric aviation (eVTOLs) and high-performance racing, where power-to-weight is the primary KPI.

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Round 3: Efficiency Maps (The marathon runner)

Peak efficiency is a vanity metric; drive cycle efficiency is what actually matters. A motor might be 98% efficient at one specific RPM, but how does it perform in stop-and-go traffic or cruising altitude?

• Radial Flux: Tends to have a "sweet spot" for efficiency. Move outside that RPM/torque band, and efficiency drops, leading to energy waste as heat.
• Axial Flux: Offers a broader high-efficiency island on the efficiency map. This is due in part to lower iron losses. Because the magnetic path is shorter, there is less resistance to the magnetic flux, maintaining high efficiency (>96%) across a wider range of speeds and loads.

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The Verdict:

For real-world applications with variable loads (like driving a car or piloting a boat), axial flux motors maximize battery range.

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Round 4: Thermal Management (The cool head)

Heat is the enemy of performance. If you can't cool a motor, you can't run it at peak power for long.

• Radial Flux: The heat-generating copper windings are often buried deep inside the stator, making them difficult to cool directly. This limits continuous power output.
• Axial Flux: The windings are typically arranged on a flat plane, often in direct contact with the casing or cooling plate. This allows for exceptional heat transfer.

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The Verdict:

Superior cooling means superior Continuous Power. While radial motors might have high peak numbers that last for 10 seconds, axial flux motors—specifically those with Beyond Motors’ patent-pending cooling system—can sustain high power outputs for dramatically longer periods without overheating.

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Conclusion: The Era of Axial Flux is Here

The showdown isn't really a fair fight anymore. While radial flux motors will always have a place in low-cost, low-performance applications (like washing machines or standard industrial fans), the future of high-performance mobility belongs to axial flux technology.

Whether it’s the superior continuous torque of the AXM2, or the massive power density of a triple-stacked AXM4, Beyond Motors is engineering the victory lap for electric propulsion.

Ready to upgrade your performance?

Configure your motor today or view our Technical Data Sheets to see the numbers for yourself. https://bmconfigurator.eu.pythonanywhere.com/enquiry

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