Electric Drive Motors for Taxi Use

[ImbracableCrunk]

You're going to be at a taxi speed and you'd only need to stop once. I'd guess most planes could handle that on accumulator pressure. It would be a pain to go dark ship half-way to the runway with no motors turning.

 

[landlover]

The problem still lies with single generator ops. If you lose the APU gen (which I have a couple of times), you now have no electric power and hence no hydraulics for brakes. Are we really going to rely on accumulator pressure in this scenario?

the battery doesn't go dead the second the APU generator quits.

 

[asayankee]

the battery doesn't go dead the second the APU generator quits.

but will battery power energize the hydraulics? Not on some planes.

 

[boxjockey]

but will battery power energize the hydraulics? Not on some planes.

I don't know about the Airbi, but on the Boeing there would be more than enough accumulator pressure to bring the aircraft to a stop. Seems like a good idea to me.

box

 

[landlover]

I don't know about the Airbi, but on the Boeing there would be more than enough accumulator pressure to bring the aircraft to a stop. Seems like a good idea to me.

box

I agree. isn't that one of the purposes of the accumulator? to stop the airplane when everything else takes a dump? I think it would be more than adequate to stop the airplane at taxi speeds. Then you reset the APU gen or fire up an engine.

 

[flyingitalian]

Its an electric motor, if it can go backwards it can stop the plane.

 

[ImbracableCrunk]

Its an electric motor, if it can go backwards it can stop the plane.

I would imagine that if the hydraulics are not powered by the batteries, then the motor for taxiing might be shed or only powered by the APU powered buses. It could have a regenerative braking system, I suppose, but that seems like it would be pretty involved.

 

[ImbracableCrunk]

WheelTug has since resolved the remaining primary
engineering questions. One widespread concern was that
the 737NG aircraft might not have sufficient electrical
power from the APU to power the drive motors and the
aircraft simultaneously. Tests conducted with
development partners in January established that the
aircraft has more than adequate power available to run
the WheelTug system, even when all other usual onground
electrical systems are also operating.

It sounds like they were concerned that the APU might not be able to handle the load. If they were concerned that the APU couldn't handle the load, then there's little likelihood that the Batts could power the system.