LaunchPoint TechBlog

11 FAQs about the LaunchPoint Dual Halbach Axial Flux Motor

Posted on Wed, Apr 13, 2011

LaunchPoint Dual Halbach Axial Flux MotorLaunchPoint Technologies has developed an electric motor that gives better power and efficiency performance per pound than any other motor commercially available.

The military, systems integrators, electric vehicle manufacturers, and remote-control UAV hobbyists have all expressed interest in our motor design.

In this blog post Mike Ricci, VP of Engineering, answers some of the most frequently asked questions (FAQs) about the LaunchPoint Dual Halbach Axial Flux motor.  

1. Can I buy the LaunchPoint motor?

The short answer is “not at this time.” We have built several prototypes and tested them to a level where we have high confidence in the basic design, but we have not yet performed HALT testing (Highly Accelerated Lifetime Testing) or tooled up to produce the motors in volume.

2. Can I hire LaunchPoint to develop a Halbach array motor for my application and what would it cost?

Definitely! Depending on your performance requirements and how far you want us to take the design, we can simply deliver a lab quality experimental prototype or take the design all the way through pre-production and high volume manufacturing ramp-up, with costs ranging from tens of thousands of dollars to millions of dollars.

3. Is the LaunchPoint Halbach array motor the “best” motor out there?

To the best of our knowledge the LaunchPoint motor can generate a higher shaft output power (per pound of motor) than any motor out there (at a given high level of efficiency and at a given relatively high speed). We welcome comments and suggestions on other motors that might rival ours.

4. Why does the LaunchPoint motor achieve better performance at relatively high speeds?

Because the motor is cooled with air drawn in by the spinning rotor, airflow is limited at stall and low speeds. As a result, the motor’s continuous stall torque is lower than the high speed running torque. If the motor is provided with an external fan, the stall torque could be greatly improved, but the power density would be decreased because of the additional weight in the system. We have ongoing R&D efforts that will greatly improve the stall torque of the motor, but specific performance predictions are not yet available for that design.

5. How does the LaunchPoint motor design impact the efficiency level?

Because the LaunchPoint motor is so power dense, it has little thermal mass and thus cannot be run at a low efficiency. You might be able to get a higher power density in a different motor design by using a liquid cooled motor that is very inefficient (<90%), but relies on the water to remove the waste heat. However, in the >90% efficient design range, you won’t find a more power-dense motor than the LaunchPoint Dual Halbach Axial Flux motor.

6. Can the LaunchPoint motor be used as a permanent magnet generator?

Definitely! Our electrical machine is the most power dense available. Whether you use it as a motor or as a generator or both, it will happily and efficiently convert electrical power into mechanical power and vice versa.

7. Can you design the LaunchPoint motor for a different size, power level, or speed?

Absolutely; we have looked at designs from 100 W to 2,000 HP and from 400 rpm to 20,000 rpm.

8. How fast can the LaunchPoint motor spin?

As presently designed, our 6 inch motor can easily spin at 12,000 rpm. With some modifications the design should be good to 20,000 rpm. Our motor has no lossy iron and can therefore run efficiently at high speeds and frequencies unlike conventional iron core motors. Because the maximum speed of a motor is roughly inversely proportional to motor diameter, larger motors would have slower speeds.

9. Should I use direct drive with the LaunchPoint motor or connect it to a gearbox?

That depends on your application. If you want the lightest weight possible and don’t need a total conversion efficiency (electrical to output shaft) of >94%, the gearbox is the way to go. Spinning the motor fast to increase power output and then reducing the speed down will always be lighter than a direct drive solution (assuming an aircraft-grade gearbox). On the other hand, direct drive may be more appropriate if you cannot tolerate the maintenance that a gearbox requires or you desire a total conversion efficiency >95% and cannot tolerate the 2% loss in efficiency caused by the gearbox.

10. What will the motor cost when it goes into production?

The costs of the materials in the LaunchPoint motor are comparable to the costs of a conventional motor with an equivalent rating. The LaunchPoint motor will probably use more rare earth magnet material than an equivalent conventional design, but it doesn’t have any iron laminations that require processing and stacking. For the prototypes that we will be building in the near term, the tooling and manual manufacturing processes will require highly skilled labor costing more than 50X the materials costs. Once we have tooled up and are doing low volume production using refined manual tooling and technician-level labor we expect our cost for the motors to be roughly 5X the materials costs. In high rate production, with automated manufacturing processes and volume pricing for materials/components from suppliers, we expect the cost of the LaunchPoint Motor to be competitive with other high-end brushless PM motors with similar ratings.

11. How can I find out more about the LaunchPoint Dual Halbach Axial Flux Motor?

You can find more information on our website under electric motor design and UAV electric propulsion.

Feel free to continue the discussion with us in the comments section below and we will answer your questions as soon as we can.

Topics: axial flux motor, Halbach array motor, LaunchPoint motor