Boeing's Electric Taxi Motor

On 19 Aug 2005 16:32:27 -0700, wrote in
.com::

Larry Dighera wrote:
On 19 Aug 2005 15:41:47 -0700, wrote in
.com::

Fixing the drive motor within the fuselage and then
having to transmitt the energy from there to the landing gear, down
the gear leg itself and then tee it to both wheels really drives up the
complexity.

If this is the system Boeing is installing:

http://www.wheeltug.gi/technology.php
http://www.chorusmotors.gi/technology/

What makes you think the motor will be installed within the fuselage?

By what they have released to the press, such as the following:

http://www.flightinternational.com/A...oeing+767.html


Thank you for the link. This is interesting information indeed:

To get more torque out of an electric motor, it is necessary to
increase the current handling capabilities of the inverter.
However, this usually requires a larger, more expensive inverter,
not all the capacity of which is usable because of limits on the
total power available. The Meshcon system gets round this by
regulating the voltage required by the inverter at various speeds,
allowing the inverter to deliver all its power at reduced motor
speeds.

Carman says the Meshcon system has been developed specifically for
traction and increased low-speed torque loads, and applications
for which starting torque requirements are higher than the
continual torque requirements. The system uses multi-phase motors
in which the windings are connecting several inverter terminals to
each other, and not the ground. The different connectors act like
different gear rates, and the motor can electronically change
"gears" by operating the inverter at the harmonics of the drive
frequency.

The system therefore uses harmonic drive to essentially fool the
drive electronics into thinking they are operating at a higher
speed. The net benefit is that the motor drive can achieve five
times the torque speed of a similarly sized machine and is
therefore much smaller and lighter.

"We believe the ability to integrate it into a weight-sensitive
application is totally feasible," adds Carman. The demonstration
is not representative of a flight-worthy system, suggesting that
the drive system is being temporarily integrated into the nose
gear bay and undercarriage leg rather than into the fuselage. The
concept dovetails with Boeing's move to a more-electric aircraft
philosophy, as is being pursued with the 787.

Now I am beginning to understand you concern about weight and
complexity.

I wonder if the electric motor could be integrated into the nose wheel
hubs and drive them through ring gear reduction. That might save some
weight and complexity at the expense of completely redesigning the
nose wheels. Alternatively the motor could be mounted at the top of
the gear leg and its shaft directed down between the wheels to a worm
gear. Of course some sort of clutch would be necessary to disengage
the electric drive system during landing I suppose.