The next-generation electric motor

Update: November 2011, promotional video from company.

Update: November 2011, many mentions of this motor in the media because of a deal with El Al. 1 2 3 4 5 6

Update: An argument for WheelTug here from Addison Schonland, who has “a doctorate in business administration from [unaccredited] Rushmore University“.

Update: A news report (in Czech with English subtitles) about a recent test of the motor for use in aircraft ground propulsion systems. Still no prototype that will fit inside the nose wheel.

Update: This new electric motor will be used in aircraft ground propulsion systems. According to Azfar A. Khan

The WheelTug system will be first used on the Boeing 737NG family of aircraft, but later on other aircraft will benefit from the technology. It will be developed eventually for narrow-bodied planes, business and regional jets and certain aircraft used by air forces around the world.


It is estimated that a WheelTug-equipped 737 aircraft could save nearly 100,000 gallons of fuel per year.


WheelTug is one of the most exciting new developments in the aviation industry. A fully integrated ground propulsion system for an aircraft, the system comprises two powerful electric motors that are installed inside the two front nose wheels of the aircraft, like the Boeing 737NG. These twin motors use electricity generated by the aircraft’s auxiliary power unit.

When switched on, WheelTug enables an aircraft to taxi and provides movement in forward and reverse directions without turning on the engines, and without needing an external tug. Using WheelTug, the aircraft can move at a speed of up to 25mph.

and according to Lisa Haddican, interviewing the WheelTug CEO (so I’d take this a with a grain of salt)

Though the system runs off the aircraft’s APU, WheelTug promotes less fuel usage, according to Isaiah Cox, CEO of WheelTug plc. “If they do a double-engine taxi, they are burning 25 pounds of fuel per minute and a single-engine taxi works out to about 17 pounds of fuel per minute,” he says. “WheelTug burns about 4 pounds per minute and that’s the difference.

“It’s a big difference when you’re talking about the taxi fuel margin,” he adds. “When the airplane is being fueled, the pilot always puts on too much fuel, because he never knows what kind of delay he might get in taxi. And so he has to have an extra 20- or 30-minute margin. It’s about 400 to 600 hundred extra pounds the aircraft flies with. With WheelTug, it would be about 80 to 100 pounds.”

That article ends with the company hoping that they’ll go into production by end of 2011, so don’t hold your breath in this tough economy. It looks like, although the next-generation motor shows a lot of promise, it can’t seem to find a job and get its own apartment. (Update: July 2011 a press release announced, “The company expects to test-drive its prototype system on a Boeing 737-800 in early 2012, and expects to begin deliveries of certificated production models by early 2013.”)

According to Frank Markus

Electric motors create a rotating magnetic field that pushes a permanent or electromagnet around and around. Electronics control the field’s strength and speed to vary output torque. For a traditional motor’s electromagnetic-field winding, rotor size, etc., it produces a certain peak torque that falls off above a certain speed. The new Chorus Meshcon motor’s “mesh-connected” winding is unique. Instead of a fixed three-phase design like your shop air-compressor uses, it’s wound in such a way that the inverter can treat it as though there are many more phases-say 12 or 18-and the software virtually “rewires” it on the fly changing the number of magnetic poles and the alternating-current frequency, so that at low speed it provides big DC-type torque, and at high speed it delivers AC-induction performance. The inverter control works like a virtual transmission, delivering big starting torque while efficiently providing strong cruising torque at all other times in a smaller, lighter, cheaper package that requires no transmission, cooling circuit, or precious rare-earth materials.

These characteristics make it ideally suited to serial hybrid cars like the Volt, employing a small combustion engine operating at peak efficiency to provide the energy for cruising and maybe using ultracapacitors to supply burst-torque energy. Chorus reckons that ditching the pricey plug-in battery and applying the cost savings of the Meshcon motor could produce a 50-mpg serial-hybrid that’s competitive with Camry and Accord on both performance and price.

According to the company’s home page

The Chorus concept utilizes concentrated, high phase order windings which allows the beneficial use of harmonics (temporal, spatial, and overload). Rather than harmonics running against the main drive (creating heat), they run with the main drive, creating more power. Consequently, a Chorus machine can achieve much higher torque densities than a traditional 3-phase motor, but with no cost penalty.

Chorus Meshcon uses the software control of the high phase order windings to ‘rewire’ the Chorus motor on the fly. The motor automatically reconfigures to operate efficiently as a low-speed, high-torque system and as a high-speed low-torque system. The result is that a much smaller drive can be used for the same load, greatly reducing the cost of the resulting drive. At the same time, high speed operation is not hampered, so the same motor can be used to start a car engine, and efficiently produce electrical output.

According to Aaron Bianco at

So how can a Series Hybrid get much better mileage if it still uses an old-fashioned internal combustion engine to generate electricity? The answer lies in the difference between the *average* power draw of a vehicle, and the *burst* power requirement that is the standard for determining vehicle performance; and Chorus Meshcon shines in this ‘burst’ torque area by uniquely providing up to 10x the standard torque for that burst that would normally come from an overpowered ICE engine in a standard vehicle.



  1. Even great technology ideas usually cannot stand alone – they must co-exist in the whole eco-system of a full design and its usage context. So, although I think the Chorus/Meshcon motor winding will be licensed for (say) automotive applications, this will only happen if it gains a toehold in the automotive design ecology – or the elevator machine world, or wind turbines, or wherever.
    Consider the praises given here to the WheelTug system. No mention of “virtual transmission” or “harmonics” – it is the business logic that’s driving this adoption. What is no more than an incremental improvement among many in the long history of induction motors becomes a revolution on the margins of the electric motor market. Pushing envelopes is always disruptive and disruptions are time-consuming.

    Come the day there’s a Chorus-driven electric car, it won’t look anything like a WheelTug system.
    The whole idea of hub-mounted motors is all wrong for a car: polar moment of inertia is bad, a big electromagnet near a tire that can be punctured is bad; heat dissipation shouldn’t be so constrained, …
    And the business logic of cars is nothing like airport ground operations. There the unit costs of the inverter components make or break whether mass production is economical. It’s only been a year since the Rare Earths shortage (favoring induction motors) was recognized. These are the facts that get put at the far left of the timeline once the story is ready to be told, if ever.

    Disclaimer: I am long shares of CHOMF and WheelTug, and still waiting for a first dividend check 😉


  2. > these APU’s are not the model of efficiency when it comes to fuel and emissions.
    Actually they’re not especially inefficient, just costly; although taking one off the airplane where you can add heavier emissions control equipment would be cleaner. In any event, the 737NG APU has unused capacity and is already operating during taxiing to hold up the life support loads.

    BTW, I predict autos will soon have APUs. When the main drive is operated in a shutdown/restart mode at each traffic light, something has to run your A/C, GPS, headlights, and a fuel cell APU beats a
    battery at this hands down.


  3. It is an improvement over using the main engines, however these APU’s are not the model of efficiency when it comes to fuel and emissions. They would be far better off using a large extension cord as most of the aircraft do not use Tugs in any form to taxi; but more to push back from the gate and out onto the taxi way.


  4. According to New Scientist

    Jet engines run at their most inefficient when used to propel planes around the taxiways. […] Airbus and the military robot maker Israel Aerospace Industries are working together to create a “taxibot” that docks with an aircraft’s nose landing gear to tow the plane.

    Pilots would guide the taxibot using their regular joystick and pedal controls. “To the pilot it would feel no different to normal taxiing with the engines,” says Airbus engineer Marc Lieber.


  5. The real deal in this choruscars expose is not just the meshcon motor, which merely facilitates the real technology. It’s also the virtual transmission — this is not much more than a specialized refinement of an emerging power electronics technology of multi-phase applications. Call it digital power control or digital multi-phasing. How do you handle the range of amps and voltages encountered in modular solar PV system builds? So that you don’t have to at all? Virtual power electronics. We have the technology.


  6. According to Leonard Bordzol on LinkedIn

    The improvements rely on putting more software under the hood, rather than new materials. This is probably the wave of the future, but I am concerned about the reliability of software in the automotive sector, especially since my OBD is giving codes that my manual says don’t exist. I think there is a future for more robust control circuits if we want to use features like this in the car of the future.


  7. Two of these little babies can be seen taxiing a B-767 in 112 degree
    heat in the summer of 2005 in this video. A version with the motors integrated into the wheel hubs goes into flight testing sometime in 2009.


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