I was just reading Motor Trend and saw this. Its the first I have heard of this technology and Delta is the launch customer. Will allow to back up the airplane and "drive" to the departure end of the runway (up to 20 MPH) with only the APU (which sends electricity to the electric motor) running saving a lot of money). Has anybody else heard about this?
http://www.motortrend.com/features/editorial/112_0901_flying_hybrids_technologue/index.html
Technologue: Flying Hybrids!
What the Next-Gen Boeing 737 Jet-Fuel / Electric Airplane Portends for Highway Hybrids
By Frank Markus
You read that right. Vehicle hybridization has turned its CO2-reducing attentions to the air-travel industry. The next-generation Boeing 737 aircraft is being adapted for use as an external-combustion/electric hybrid, with the small on-board auxiliary-power unit turbine generating enough electricity to propel the aircraft under certain circumstances at speeds of up to 20 mph. Okay, taxiing under electric power may not seem glamorous, but trust me, you'll love it.
Imagine being able to leave the gate as soon as the last overstuffed suitcase has been jammed into an overhead bin without waiting for an airport tug and driver to push the plane out to the active taxiway. Green-minded travelers will love the fact that letting electric motors tow them all the way out to the runway saves tons of CO2 and precious jet fuel. One estimate suggests that leaving a new 737's wing engines off while taxiing and idling before takeoff could save 200 pounds of fuel per flight, eliminating 500-1000 tons of CO2 per plane per year depending on its flight schedule.
Other cost savings include reduced brake wear, no damage from clumsy airport-tug operators, and reduced turn-around time because ground personnel won't have to wait for engines to cool. All together, total monthly savings could reach $60,000, according to Isaiah Cox, CEO of WheelTug, the subsidiary of Chorus Motors plc., which is developing the concept. Surely some of that savings will trickle down to lower ticket prices.
So how does an electric wheel motor small enough to go up and down on a plane's landing gear manage to pack enough punch to accelerate a 300,000-pound aircraft to 20 mph? With black magic and witchcraft (well, their words are "mesh-connected windings" and "fundamental harmonics"-visit chorusmotors.com). These esoteric concepts combine to deliver the efficient low-speed torque of a permanent magnet motor (such as the ones in most hybrid cars) with the light weight, lower cost, and better high-speed performance of an AC induction motor (as in the Tesla and Chevy Volt).
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.
Delta Airlines will get the first WheelTug-equipped 737s by late 2009, and at least one automaker is talking with Chorus as we go to press. Let's hope it's GM, working on that club-sport, plugless Volt.
http://www.motortrend.com/features/editorial/112_0901_flying_hybrids_technologue/index.html
Technologue: Flying Hybrids!
What the Next-Gen Boeing 737 Jet-Fuel / Electric Airplane Portends for Highway Hybrids
By Frank Markus
You read that right. Vehicle hybridization has turned its CO2-reducing attentions to the air-travel industry. The next-generation Boeing 737 aircraft is being adapted for use as an external-combustion/electric hybrid, with the small on-board auxiliary-power unit turbine generating enough electricity to propel the aircraft under certain circumstances at speeds of up to 20 mph. Okay, taxiing under electric power may not seem glamorous, but trust me, you'll love it.
Imagine being able to leave the gate as soon as the last overstuffed suitcase has been jammed into an overhead bin without waiting for an airport tug and driver to push the plane out to the active taxiway. Green-minded travelers will love the fact that letting electric motors tow them all the way out to the runway saves tons of CO2 and precious jet fuel. One estimate suggests that leaving a new 737's wing engines off while taxiing and idling before takeoff could save 200 pounds of fuel per flight, eliminating 500-1000 tons of CO2 per plane per year depending on its flight schedule.
Other cost savings include reduced brake wear, no damage from clumsy airport-tug operators, and reduced turn-around time because ground personnel won't have to wait for engines to cool. All together, total monthly savings could reach $60,000, according to Isaiah Cox, CEO of WheelTug, the subsidiary of Chorus Motors plc., which is developing the concept. Surely some of that savings will trickle down to lower ticket prices.
So how does an electric wheel motor small enough to go up and down on a plane's landing gear manage to pack enough punch to accelerate a 300,000-pound aircraft to 20 mph? With black magic and witchcraft (well, their words are "mesh-connected windings" and "fundamental harmonics"-visit chorusmotors.com). These esoteric concepts combine to deliver the efficient low-speed torque of a permanent magnet motor (such as the ones in most hybrid cars) with the light weight, lower cost, and better high-speed performance of an AC induction motor (as in the Tesla and Chevy Volt).
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.
Delta Airlines will get the first WheelTug-equipped 737s by late 2009, and at least one automaker is talking with Chorus as we go to press. Let's hope it's GM, working on that club-sport, plugless Volt.
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