Engines off, to the runway

It's an interesting concept. Will it make takeoff from a conveyor belt simpler? ;)
 
They have long been missing the ball on large aircraft by not having electric motors in the wheels for maneuvering, but also using them for dynamic braking - with or without with a set of brake pucks... This would drastically reduce the temperatures near the tires and stop fires from igniting... Another added benefit is the ability to spin up the tires on short final and prolong tire life...
The biggest issue I would see with using the wheel motors to back out of the gate might be on ice where wheel spin could occur... But then, even the tugs have that problem when it is bad enough...
In the future dramatic puffs of smoke from tires hitting the pavement and from hot braking will become the past...

denny-o
 
Dr. O said:
They have long been missing the ball on large aircraft by not having electric motors in the wheels for maneuvering, but also using them for dynamic braking - with or without with a set of brake pucks... This would drastically reduce the temperatures near the tires and stop fires from igniting... Another added benefit is the ability to spin up the tires on short final and prolong tire life...
The biggest issue I would see with using the wheel motors to back out of the gate might be on ice where wheel spin could occur... But then, even the tugs have that problem when it is bad enough...
In the future dramatic puffs of smoke from tires hitting the pavement and from hot braking will become the past...

denny-o
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The weight of the electric motors and associated equipment turn out to cost more than they save. Also, the whole myth of spinning up tires to save them from wear has been tried, and AFAIK, it didn't do much.
 
Let'sgoflying! said:
They would rely on the accumulator for brakes, battery for comm, Greg?
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Well, I kind of misread the post. No reason NOT to use the APU, which would provide the electricity needed, and the air for engine starts. Electric hydraulic pumps. But the tug would provide the braking power anyway.
 
KSCessnaDriver said:
The weight of the electric motors and associated equipment turn out to cost more than they save. Also, the whole myth of spinning up tires to save them from wear has been tried, and AFAIK, it didn't do much.
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That's pretty much why I figured they never bothered. Sure, there's a potential fuel savings on the ground (I could especially see this when you're #47 in line out of Newark) but I'd be interested to see how that averages out compared to MX and weight penalties.
 
Ted DuPuis said:
That's pretty much why I figured they never bothered. Sure, there's a potential fuel savings on the ground (I could especially see this when you're #47 in line out of Newark) but I'd be interested to see how that averages out compared to MX and weight penalties.
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One reason many carriers are swapping over to carbon brake linings is the weight reduction. On a B757 the carbon linings save 600+ pounds.
 
Rotor&Wing said:
One reason many carriers are swapping over to carbon brake linings is the weight reduction. On a B757 the carbon linings save 600+ pounds.
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Makes sense to me. I was thrilled to lose 65 lbs when the Aspen got installed into the 310.

I'd suspect the motors and such would add about 1000 lbs or more. Just a SWAG.
 
My father flew a model 60 sabreliner for a long time. He always said that he wished he could get someone to pull them to the end of the runway because it used as much fuel on taxi as it did at altitude.

Kevin
 
Ted DuPuis said:
Makes sense to me. I was thrilled to lose 65 lbs when the Aspen got installed into the 310.

I'd suspect the motors and such would add about 1000 lbs or more. Just a SWAG.
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Maybe a lot more once the gearsets and all are figured into it. That might come down with the newer brushless DC motors, but it still adds weight and take up room. And they still need power, so probably would need a much bigger APU (that burns more fuel) just to taxi. Probably cheaper and simpler to leave it all off and use the room for several more paying passengers to cover the fuel burn on taxi and tire wear on landing.

One old jock told me that it wasn't the landings that did the most damage to the tires, anyway; it's the braking forces that rub it off. And several others say the sharp taxiing turns scuff the tires and leave lots of little bits on the taxiways at the corners. That rubber doesn't show up as spectacular big black marks. I can imagine the damage a crabbed crosswind touchdown does to the tires; if they have wheel spinup they might as well have steerable mains to align them with the runway, too. More mechanisms and weight.

Dan
 
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