Boeing's Electric Taxi Motor

"Peter Duniho" writes:

My point was simply that the press release is incredibly vague; we really
have no idea *what* this device is, how it works, or how practical it will
be. I suspect it will turn out to be a good idea, but it's hard to know
without any actual information.

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

--kyler

Just brainstorming so this may be a completely wrong idea.

If these electric motors are more effecient than running the engines on the
jets for taxi purposes and will save the airlines 'considerable' fuel costs
for the taxi operations, do the electric motors need to be 'installed' on
the jets? How about using these efficient electric motors on the tugs, use
the tugs to push/pull the jet from the gate all the way to the hold short
line while the jet is just idling. Then have the electric tugs 'race' down a
taxiway to take the arrivals back to a gate. This would mean more tugs and
personnel to drive them.

Just an (dumb?) idea....

Where will you find the BTUs to charge the tugs? Isn't the theory that
the plane has free amps to spare either from an APU that must be running
anyway or batteries charged off the main engines while flying much like
free heat to warm your automobile.

"N93332" wrote in message
...
Just brainstorming so this may be a completely wrong idea.

If these electric motors are more effecient than running the engines
on the jets for taxi purposes and will save the airlines
'considerable' fuel costs for the taxi operations, do the electric
motors need to be 'installed' on the jets? How about using these
efficient electric motors on the tugs, use the tugs to push/pull the
jet from the gate all the way to the hold short line while the jet is
just idling. Then have the electric tugs 'race' down a taxiway to take
the arrivals back to a gate. This would mean more tugs and personnel
to drive them.

Just an (dumb?) idea....

"sfb" wrote in message news:NcHMe.7384$rR4.2590@trnddc08...
Where will you find the BTUs to charge the tugs? Isn't the theory that the
plane has free amps to spare either from an APU that must be running
anyway or batteries charged off the main engines while flying much like
free heat to warm your automobile.

"N93332" wrote in message
...
Just brainstorming so this may be a completely wrong idea.

Ok, some way to electrically connect the tug to the jet to use the jet's
'free' amps? Charge the tug while it is tugging?

I'm quite sure the device will be powered by the APU, which will
produce electricity and air conditioning for all the equipment, and the
pressurized air needed to start the engines later.

An idling jet engine uses a TON of fuel and makes quite a bit of
thrust; aside from initially getting the plane moving, taxiing is
normally done at idle thrust anyway. But it's that high idle fuel
consumption that this will eliminate for the taxi-out, and I think it's
a terrific idea.

Just to throw some numbers out, an older 737's engine (I don't have
specs in front of me for the newer ones) burns about 1200 pounds of
fuel per hour, per engine, at idle.. The APU burns about 300 pounds
per hour. A savings of 900 pounds, or about 135 gallons of fuel per
hour over a single-engine taxi. (315 gallons less than a more-common
two-engine taxi!)

Jet fuel's costing the airlines upwards of $1.75 a gallon. For every
minute the airplane could taxi using only the APU instead of one
engine, an airline would save about $4. A typical 15-minute taxi-out
at a semi-busy airport would save $60. An hour-long taxi on a bad
weather day? $240.

Obviously the economics will be different for each airplane type, and
for some airlines like Southwest that don't normally fly into
delay-prone airports, it might not make financial sense to install this
device.

But an airline that flies to LaGuardia, Chicago O'Hare, Atlanta, etc.,
all day long? It could save a ton of money if they can make it work.

--
Garner R. Miller
ATP/CFII/MEI
Clifton Park, NY =USA=

wrote:
It's probably some kind of ultra high voltage DC pancake motor that
would require it's own special APU to power it. It would have to
develope on the order of three to four hundred horsepower to be able to
reliably move a fully loaded jet around under all the taxi conditions
that a jet might see. In addition it would either have to be able to
spool up at a fast enough rate as to not rip the nose gear tires off
the rims on landing or be disconnected from the nose wheels on landing.

I was pondering a similar question earlier this week as I watched
gasoline prices increase.
The conversion from horsepower to kilowatts is 1:0.75, so a 400 hp
engine is 300 kw.
I was curious as to how large a 300 kw motor is and how massive the
power cables are to provide the requisite voltage and current.
1000 V and 300 A?
How much energy is lost to heating?
How does one reduce this heating loss?
How many kw does it take to start a given mass moving?
I am guessing there is an initial surge current, followed by reduction
in current once the mass is in motion and to keep it moving.

Larry Dighera wrote:
BOEING CO. has tested an electric motor that could allow
commercial jets to taxi around airports without using their
engines or ground-based towing vehicles, the company said.

Other pluses for this is increased worker safety (running jet engines can be
a tad dangerous and noisy), and improved passenger comfort as the terminal
would no longer smell like a leaky tank of kerosene.

I like it. Or something like it anyway.

john smith wrote:
I was pondering a similar question earlier this week as I watched
gasoline prices increase.
The conversion from horsepower to kilowatts is 1:0.75, so a 400 hp
engine is 300 kw.
I was curious as to how large a 300 kw motor is and how massive the
power cables are to provide the requisite voltage and current.
1000 V and 300 A?
How much energy is lost to heating?
How does one reduce this heating loss?
How many kw does it take to start a given mass moving?
I am guessing there is an initial surge current, followed by reduction
in current once the mass is in motion and to keep it moving.

To give you a couple of size references, we had a 25 hp DC motor that
was set to move a carriage that could weigh as much as 1500 pounds up
and down a column. The engineering requirement was for the motor to be
able to accelerate the carriage from a stop to the furthermost position
(12 feet up)in something under 4 seconds and the placement be within
..1". The power was provided by a high voltage DC unit producing 900 VDC
and up to 100 amps current. The motor case was about 10" in diameter
and about 20" long and weighed over 75 pounds. The power supply was a
little bigger than a 21" monitor but required 220/3Phase to operate.

An air compressor that I used to run had a 1750 hp open frame motor
for the main drive. It was 10 feet in diameter and 3 feet thick. It
took a special 1700 VAC/3P feed and took nearly 2 minutes to come up to
steadystate speed.

What they are going to find in the end, is that putting some kind of
electric taxi system on the individual aircraft is going to backfire
and cost them seat and cargo capacity that outweighs the supposed saved
fuel costs.

Craig C.

On Wed, 17 Aug 2005 14:24:27 -0400, "JohnH"
wrote in ::

Larry Dighera wrote:
BOEING CO. has tested an electric motor that could allow
commercial jets to taxi around airports without using their
engines or ground-based towing vehicles, the company said.

Other pluses for this is increased worker safety (running jet engines can be
a tad dangerous and noisy), and improved passenger comfort as the terminal
would no longer smell like a leaky tank of kerosene.


Additionally, light aircraft taxiing to the rear of airliners would
not be so precariously subject to upset by jet blast.

But the best improvement will be to decrease the 17,523-million*
gallons of jet fuel the airlines consume annually. Any reduction in
petroleum emissions will benefit the environment, the economy and
reduce US dependence on foreign oil.



* http://www.aopa.org/whatsnew/factcard.pdf

wrote:
It's probably some kind of ultra high voltage DC pancake motor that
would require it's own special APU to power it.

What powers an APU? diesel fuel or something?