2H4
Topic Author
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 3:29 pm

....From FlightGlobal:

---------------------------------------------------------------
Airbus UK has applied for a US patent for an A320 power system that stores the kinetic energy of rotating wheels in order to help retract and deploy the landing gear and brake the aircraft on landing.

Benefits of the scheme, according to Airbus, include cutting down on the number of redundant cable and pipe runs between centralized electric, hydraulic or pneumatic power generators, typically driven by the engines, and the localized functions, like landing gear extension and retraction systems.

The system would use generators coupled to one of more of wheels on the landing gear. When the wheels spin during takeoff, the generators produce electrical energy which is then stored in a battery or other energy storage device. The stored energy would then be used to retract the gear after takeoff.

During landing, the gravity-assisted free-falling landing gear would internally generate power via the damping system that would then be used to spin up the wheels, which in turn would provide power to complete the landing gear deployment.

Once on the ground, the wheels' kinetic energy would be used to partially or fully power the braking system.

---------------------------------------------------------------

Full article here.

2H4
Intentionally Left Blank
 
Tristarsteve
Posts: 3363
Joined: Tue Nov 22, 2005 11:04 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 4:48 pm

It looks like the PR dept released this a week early.  biggrin 
 
User avatar
vzlet
Posts: 818
Joined: Thu Mar 11, 2004 10:34 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 5:18 pm

They'll have to rebadge all planes so equipped:
Big version: Width: 425 Height: 138 File size: 6kb
"That's so stupid! If they're so secret, why are they out where everyone can see them?" - my kid
 
Lemmy
Posts: 243
Joined: Fri Dec 10, 2004 8:40 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 7:41 pm

Interesting. I had a hard time imagining that it would ever be economic to install electric motors in the gear to taxi on. But if those motors also store energy through regenerative braking on landing, then it makes more sense.

Obviously, Airbus has thought this through. But I'm wondering just how much gas this'll save. I mean, motors and batteries are heavy things to carry around.

Instead they should store the rotational energy in a huge flywheel mounted to the top of the plane. Just think of the added stability! (Kidding, of course)
I am a patient boy ...
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 8:11 pm



Quoting Lemmy (Reply 3):
Instead they should store the rotational energy in a huge flywheel mounted to the top of the plane. Just think of the added stability! (Kidding, of course)

When I first read the title of this thread, actually, I was imagining it was going to involve flywheels...  Wink

Either that, or a Johnson bar like a '60s vintage Mooney  Wow!
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
lowrider
Posts: 2542
Joined: Wed Jun 30, 2004 3:09 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 10:08 pm

It will be interesting to see how they solve issues like a redundent extension system, and reserve braking. I would also be interested to see what is deferable and with what penalty. At first glance, it does seem like it would be a self regulating anti skid though. In someways it reminds me of the old Maxaret systems.
Proud OOTSK member
 
2H4
Topic Author
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 10:11 pm



Quoting Lowrider (Reply 5):
It will be interesting to see how they solve issues like a redundent extension system, and reserve braking.

On takeoff, the treadmill provides excess spin-up and that power is stored in a separate system.

2H4
Intentionally Left Blank
 
Rj111
Posts: 3007
Joined: Wed Sep 08, 2004 9:02 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 10:40 pm

I read something about this in FI a few months back.

Seems like a very creative system, and it's hard to imagine, with the weight of the motors and battery, that it would work out ulitmately economical.
 
lowrider
Posts: 2542
Joined: Wed Jun 30, 2004 3:09 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 10:48 pm



Quoting 2H4 (Reply 6):
treadmill

Excellent. Anet solves yet another aviation quandry.
Proud OOTSK member
 
User avatar
jetmech
Posts: 2316
Joined: Wed Mar 29, 2006 2:14 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 11:06 pm



Quoting 2H4 (Thread starter):
The system would use generators coupled to one of more of wheels on the landing gear. When the wheels spin during takeoff, the generators produce electrical energy which is then stored in a battery or other energy storage device


This is the bit I don't get. If the generators are producing a charging current during take off, this energy itself must come from somewhere. The end result will be that the engines will have to operate at a higher power setting to overcome the back EMF of the in-wheel generators. Not having a go at you personally BTW.

Quoting Lemmy (Reply 3):
But if those motors also store energy through regenerative braking on landing, then it makes more sense.

This makes more sense to me as well.

Quoting Lemmy (Reply 3):
But I'm wondering just how much gas this'll save. I mean, motors and batteries are heavy things to carry around.



Quoting RJ111 (Reply 7):
and it's hard to imagine, with the weight of the motors and battery, that it would work out ulitmately economical.

Exactly. The main problem I see is the loss in efficiency when going from one form of energy to another. Obviously, the engine would lose some additional power to the external gearbox when the hydraulic pump is running to retract the gear, but this has to be more efficient than converting engine thrust into electrical power via the wheels  Smile !

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
2H4
Topic Author
Posts: 7960
Joined: Tue Oct 19, 2004 11:11 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 11:10 pm



Quoting JetMech (Reply 9):
Not having a go at you personally BTW.

No worries, I wouldn't have assumed so.  Smile

Perhaps Airbus knows and accepts that the present-day limitations of energy storage make this concept unfeasible, and are simply staking their claim on the concept in preparation for future advances that might make it workable.

2H4
Intentionally Left Blank
 
User avatar
jetmech
Posts: 2316
Joined: Wed Mar 29, 2006 2:14 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Mar 25, 2009 11:31 pm

Quoting 2H4 (Reply 10):
Perhaps Airbus knows and accepts that the present-day limitations of energy storage make this concept unfeasible, and are simply staking their claim on the concept in preparation for future advances that might make it workable.


Hmmm. I'm not an A or B fan myself, but it does seem that a lot of these far into the future concepts are usually attributable to A   .

Anyway, I accept that a more efficient electrical charge storage device may be on the horizon, but still, it is the efficiency of the electrical generation technique that makes no sense to me.

On you car for example, you have an alternator to generate current for the electrical system. This is usually driven off the serpentine or fan belt. The electrical power generated has its origin in the fuel combusted by the engine.

In this case, the potential energy content in the fuel is reduced by the thermal efficiency of the engine, the mechanical losses in the serpentine belt (quite small), and the mechanical to electrical efficiency of the alternator.

Now imagine if the alternator was an in-wheel design as proposed by Airbus. In addition to the losses incurred due to the thermal efficiency of the engine and the mechanical to electrical efficiency of the alternator, we now have to add in the losses due to the mechanical (in)efficiency of the driveline (significant).

The end result is we have to combust much more fuel in the engine to get a certain output from the alternator. The same thing is occurring with this Airbus concept. Especially during takeoff, due to the large difference between exhaust gas and aircraft velocities, the propulsive efficiency of the engine is quite low.

I accept that there are losses in the traditional hydraulic set-up to retract landing gears, but still, the whole idea of using jet engine thrust to generate power through the wheels seems like a backward step to me   !

Regards, JetMech

N.B. If the Flight-global article actually means wheel-spin after the plane has left the ground, then it makes much more sense  blush  !

[Edited 2009-03-25 16:49:28]
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Thu Mar 26, 2009 1:34 am



Quoting JetMech (Reply 9):
This is the bit I don't get. If the generators are producing a charging current during take off, this energy itself must come from somewhere. The end result will be that the engines will have to operate at a higher power setting to overcome the back EMF of the in-wheel generators.

What they *might* mean is that you don't use the system during the takeoff roll, you use it after you leave the ground to spin the wheels down and power the gear retract system. The wheels will have a not insignificant amount of kinetic energy at liftoff. That relieves the engines of having to drive the wheel-generators during roll, and lets you productively use the energy you'd otherwise waste in the wheel braking prior to retraction.

Quoting 2H4 (Reply 10):
Perhaps Airbus knows and accepts that the present-day limitations of energy storage make this concept unfeasible, and are simply staking their claim on the concept in preparation for future advances that might make it workable.

I strongly suspect this is the case...I can't see how it works out on a weight basis using today's motor/generators and batteries, but it might in the future and it can't hurt to plant their flag on the idea. Plus, it makes for good environmental PR even if they never build it.

I'm not so sure about using it for braking on landing...the total brake power output during an A320 landing is something on the order of 10MW. I'm not sure we've got battery or generator technology at the required size that can handle that kind of power.

Tom.
 
TSS
Posts: 2483
Joined: Fri Dec 29, 2006 3:52 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Thu Mar 26, 2009 3:00 am

I'm no engineer, but it seems to me the whole wheel-mounted generator and associated storage battery for the energy is kinda going the long way around a relatively short problem, Rube Goldberg-style. Why not just have the fairings that are mounted to the sides of the landing gear (the main ones, anyway) be slightly articulated and steerable so that the force of air over them at speed causes them to go into the up & locked position on takeoff and with a slight control tweak causes them to drop into the down & locked position just before landing?
The system I've just described or something along those lines was what I envisioned when I read the title of this thread.
Able to kill active threads stone dead with a single post!
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Thu Mar 26, 2009 4:58 am



Quoting TSS (Reply 13):
Why not just have the fairings that are mounted to the sides of the landing gear (the main ones, anyway) be slightly articulated and steerable so that the force of air over them at speed causes them to go into the up & locked position on takeoff and with a slight control tweak causes them to drop into the down & locked position just before landing?

I like the simplicity of a motor/generator/battery than I do of an aerodynamic surface literally flying the gear up and down.

Tom.
 
rwessel
Posts: 2448
Joined: Tue Jan 16, 2007 3:47 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Thu Mar 26, 2009 6:36 am



Quoting Tdscanuck (Reply 12):
What they *might* mean is that you don't use the system during the takeoff roll, you use it after you leave the ground to spin the wheels down and power the gear retract system. The wheels will have a not insignificant amount of kinetic energy at liftoff. That relieves the engines of having to drive the wheel-generators during roll, and lets you productively use the energy you'd otherwise waste in the wheel braking prior to retraction.

That's actually pretty easy to do - don't energize the field coils until after takeoff, and then you can bleed off the stored energy in the rotating wheel. And before you energize the coils, the generator presents essentially no drag (beyond whatever its rotating mass contributes) to the wheel.

Quoting Tdscanuck (Reply 12):
I'm not so sure about using it for braking on landing...the total brake power output during an A320 landing is something on the order of 10MW. I'm not sure we've got battery or generator technology at the required size that can handle that kind of power.

You don't need all that much power - you just need enough to squeeze the braking surfaces together.

But I'm not seeing how this scheme makes any practical sense...
 
rheinwaldner
Posts: 1249
Joined: Wed Jan 02, 2008 4:58 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Thu Mar 26, 2009 8:15 am



Quoting Rwessel (Reply 15):
But I'm not seeing how this scheme makes any practical sense...

Me too. Either some explanation is missed or the idea is useless. All that additional hardware to save what? Some wires and tubes? IMO BS.
 
User avatar
DocLightning
Posts: 19762
Joined: Wed Nov 16, 2005 8:51 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Thu Mar 26, 2009 4:34 pm



Quoting 2H4 (Reply 6):

On takeoff, the treadmill provides excess spin-up and that power is stored in a separate system.

Oh no he didn't!
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
DaBuzzard
Posts: 66
Joined: Fri Sep 07, 2007 6:11 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Thu Mar 26, 2009 8:29 pm



Quoting DocLightning (Reply 17):
Oh no he didn't!

Shhhh, maybe no one noticed.....  crossfingers 
 
User avatar
jetmech
Posts: 2316
Joined: Wed Mar 29, 2006 2:14 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Fri Mar 27, 2009 12:38 am



Quoting Tdscanuck (Reply 12):
What they *might* mean is that you don't use the system during the takeoff roll, you use it after you leave the ground to spin the wheels down and power the gear retract system. The wheels will have a not insignificant amount of kinetic energy at liftoff. That relieves the engines of having to drive the wheel-generators during roll, and lets you productively use the energy you'd otherwise waste in the wheel braking prior to retraction.

I think this is it. I misread the original article and was a bit too keen to shoot it down  blush !

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
User avatar
SEPilot
Posts: 4961
Joined: Sat Dec 30, 2006 10:21 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Fri Mar 27, 2009 8:40 pm

I think this is a case of environmental activists going amok. I cannot imagine that it will be practical; the added weight will cost more in fuel consumption than the energy for retracting and extending the gear will ever save. Plus electric actuators are almost invariably heavier than hydraulic for the same function.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
onetogo
Posts: 286
Joined: Thu Feb 02, 2006 1:40 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Fri Mar 27, 2009 11:51 pm

Why bother putting a generator on the wheels (which, as jetmech points out, will create some resistance) when you have two very powerful turbine engines spinning dedicated generators already? Not as if the generators are even remotely close to their "load limit" at any phase of flight. Strange, indeed.
 
baroque
Posts: 12302
Joined: Thu Apr 27, 2006 2:15 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sat Mar 28, 2009 2:02 pm



Quoting Tdscanuck (Reply 12):
What they *might* mean is that you don't use the system during the takeoff roll, you use it after you leave the ground to spin the wheels down and power the gear retract system. The wheels will have a not insignificant amount of kinetic energy at liftoff. That relieves the engines of having to drive the wheel-generators during roll, and lets you productively use the energy you'd otherwise waste in the wheel braking prior to retraction.

That is what I understood too. Would there be a tyre life improvement and less tendency for blowouts on landing if the wheels have been at least partly spun up to speed?

Would it not be an A320KERS, or some seem to think the suffix would be spelled slightly differently! Or is KERS already copyrighted?
 
lowrider
Posts: 2542
Joined: Wed Jun 30, 2004 3:09 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sat Mar 28, 2009 4:06 pm



Quoting Baroque (Reply 22):
Would there be a tyre life improvement and less tendency for blowouts on landing if the wheels have been at least partly spun up to speed?

Yes. There is actually a patent on a very simple system to spin up the tires using aerodynamic forces, but the licensing and installation costs are prohibitive.
Proud OOTSK member
 
User avatar
DocLightning
Posts: 19762
Joined: Wed Nov 16, 2005 8:51 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sun Mar 29, 2009 8:47 pm

I've always wondered why they don't have electromagnetic brakes on landing gear.

For those of you who don't get what I'm talking about, imagine a horseshoe-shaped magnet.

Now, imagine a flat piece of metal passing between the north and south poles of the horseshoe (so that the horseshoe is straddling the flat plate). If that plate moves in any direction, the magnetic field sets up movement in the electrons in the metal. These "eddy currents" rob the plate of energy and force it to slow down. The faster the metal is moving, the greater the retarding force. As the plate slows, the braking effect diminishes. The energy is transferred to the metal plate as heat, but no physical contact is required between the magnet and the plate for the braking effect. Thus, there is no direct friction, even though the rotating plate will get very hot.

You can, instead of using a permanent magnet, use an electromagnet that can be turned on and off. So on landing, you'd turn on the electromagnet and slow the aircraft. Once the plane had slowed down to a reasonable speed the magnets would be turned off and normal brakes would be used.

It strikes me that this would not add a lot of weight (modern electromagnets can be very strong while being very tiny) but would save a lot on brake pads.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
zanl188
Posts: 3443
Joined: Sat Oct 21, 2006 9:05 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sun Mar 29, 2009 9:03 pm



Quoting DocLightning (Reply 24):
You can, instead of using a permanent magnet, use an electromagnet that can be turned on and off. So on landing, you'd turn on the electromagnet and slow the aircraft. Once the plane had slowed down to a reasonable speed the magnets would be turned off and normal brakes would be used.

It strikes me that this would not add a lot of weight (modern electromagnets can be very strong while being very tiny) but would save a lot on brake pads.

Such an installation would, by necessity, be rather heavy. Why? because you have to do something with all that energy - the energy of the stopping aircraft & the energy required to energize the electromagnet - the brakes are going to melt if not designed carefully.

If you're interested google "dynamic brakes'. The Railroads have been using the scheme you describe for decades. The dynamic brakes of a locomotive generate electricity which is dissipated by heating elements, i.e. the energy is given up as heat to the atmosphere...
Legal considerations provided by: Dewey, Cheatum, and Howe
 
User avatar
DocLightning
Posts: 19762
Joined: Wed Nov 16, 2005 8:51 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sun Mar 29, 2009 10:06 pm



Quoting ZANL188 (Reply 25):

Such an installation would, by necessity, be rather heavy. Why? because you have to do something with all that energy - the energy of the stopping aircraft & the energy required to energize the electromagnet - the brakes are going to melt if not designed carefully.

The electromagnet doesn't need much energy. In fact, it could even be energized by the rotation of the wheels. I estimate that the whole thing could be done for less than 10kg per truck.

As for the heat, it doesn't generate any more heat than friction brakes do. Either way, the energy needs to be dissipated. Toyota currently uses a modification on the Prius. The wheels drive a generator, so when you hit the brakes (or shift into low gear), the generator kicks into gear and pulls energy from the wheels. This is why the Prius has been going about 70,000 miles before needing the brake pads replaced.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
SEPilot
Posts: 4961
Joined: Sat Dec 30, 2006 10:21 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sun Mar 29, 2009 11:21 pm



Quoting DocLightning (Reply 26):
The electromagnet doesn't need much energy. In fact, it could even be energized by the rotation of the wheels. I estimate that the whole thing could be done for less than 10kg per truck.

I think you have no idea of what kind of energy is required to stop an aircraft. There still ain't no free lunch; the kinetic energy of the moving plane must be converted to another form of energy, and that is usually heat. The most efficient way to do this is friction; it is also the lightest way. Locomotives already have electric motors attached to the wheels, and they are basically totally indifferent to weight (in fact, they need as much as they can get) so it makes sense for them to do it. The same does not apply to airliners. Converting the energy of the landing aircraft to electricity and then converting the electricity to heat would make Rube Goldberg smile. Nobody else would.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
zanl188
Posts: 3443
Joined: Sat Oct 21, 2006 9:05 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sun Mar 29, 2009 11:27 pm



Quoting DocLightning (Reply 26):
As for the heat, it doesn't generate any more heat than friction brakes do. Either way, the energy needs to be dissipated. Toyota currently uses a modification on the Prius. The wheels drive a generator, so when you hit the brakes (or shift into low gear), the generator kicks into gear and pulls energy from the wheels.

... and the energy goes where? I don't know much about the Prius but I suspect the energy goes to a battery which is heavy. Great for the Prius which as I understand needs the battery anyway and can reuse the energy, not so great for an aircraft brake. Remember the aircraft brake must be capable of absorbing all the energy of a rejected takeoff and that energy has to go somewhere safe - doesn't seem very likely to me that the aircraft would be able to reuse this energy as the Prius can..... Best thing to do is get rid of it as heat which a traditional brake does simply and efficiently....
Legal considerations provided by: Dewey, Cheatum, and Howe
 
zanl188
Posts: 3443
Joined: Sat Oct 21, 2006 9:05 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sun Mar 29, 2009 11:42 pm

Time to roll out the 777 RTO test video from "21st Century Jet".

9.7 million ft/lbs!... yow. That'd melt a Prius battery or two....  Smile

http://www.youtube.com/watch?v=wXpjBxD0Rhg
Legal considerations provided by: Dewey, Cheatum, and Howe
 
User avatar
SEPilot
Posts: 4961
Joined: Sat Dec 30, 2006 10:21 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Sun Mar 29, 2009 11:46 pm



Quoting ZANL188 (Reply 28):
... and the energy goes where? I don't know much about the Prius but I suspect the energy goes to a battery which is heavy. Great for the Prius which as I understand needs the battery anyway and can reuse the energy, not so great for an aircraft brake.

This is in fact the main advantage of hybrid technology; it is able to capture and reuse some of the energy from braking. That is why the hybrids do so much better than conventional vehicles in city driving, but when you take them on the highway they don't have much of an advantage at all. The same applies to airliners; they really don't do much stop-and-go driving, and trying to store the energy gained from braking would add so much weight that it would make the plane less efficient and more expensive.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Mon Mar 30, 2009 2:22 am



Quoting DocLightning (Reply 24):
I've always wondered why they don't have electromagnetic brakes on landing gear.

Because most of the mass of the brake is taken up by the material you need to absorb the heat, which wouldn't change with the electromagnetic brake. So all you're trading is weight of the electromagnet against weight of the pads...although you can get very good electromagnets now, pads are incredibly simple and reliable. This may be a case of "if it ain't broke, don't fix it." Even if they weight payoff is positive, it might be so small positive that it doesn't justify the development and certification hurdles of going to an entirely new braking technology.

Tom.
 
User avatar
DocLightning
Posts: 19762
Joined: Wed Nov 16, 2005 8:51 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Mon Mar 30, 2009 6:44 pm



Quoting SEPilot (Reply 27):

I think you have no idea of what kind of energy is required to stop an aircraft. There still ain't no free lunch; the kinetic energy of the moving plane must be converted to another form of energy, and that is usually heat. The most efficient way to do this is friction; it is also the lightest way. Locomotives already have electric motors attached to the wheels, and they are basically totally indifferent to weight (in fact, they need as much as they can get) so it makes sense for them to do it. The same does not apply to airliners. Converting the energy of the landing aircraft to electricity and then converting the electricity to heat would make Rube Goldberg smile. Nobody else would.

Nope. In electromagnetic braking, the rotor heats up, same as it does in standard braking. The difference is that there's no direct friction to wear out a brake pad in the process.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
SEPilot
Posts: 4961
Joined: Sat Dec 30, 2006 10:21 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Mon Mar 30, 2009 11:13 pm



Quoting DocLightning (Reply 32):

Nope. In electromagnetic braking, the rotor heats up, same as it does in standard braking. The difference is that there's no direct friction to wear out a brake pad in the process.

But it would be much, much heavier to achieve the same braking force. This is a total non-starter for aircraft.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
zanl188
Posts: 3443
Joined: Sat Oct 21, 2006 9:05 pm

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Tue Mar 31, 2009 12:56 am



Quoting SEPilot (Reply 33):
But it would be much, much heavier to achieve the same braking force. This is a total non-starter for aircraft.

I have wonder how an electromagnet braking system would handle antiskid? Seems to me it would lack the fine control necessary....
Legal considerations provided by: Dewey, Cheatum, and Howe
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Tue Mar 31, 2009 4:20 am



Quoting ZANL188 (Reply 34):
I have wonder how an electromagnet braking system would handle antiskid? Seems to me it would lack the fine control necessary....

In theory, the reaction time of an electromagnetic brake could be faster than a hydraulic...the cycle time of an electromagnetic brake is just limited by the switching speed of the electronics, which can be very high. The cycle time for a hydraulic brake is limited by the mass of the moving bits (pistons, pads, etc.) and the flow of hydraulic fluid in the lines. The speed of an electronic pulse is far faster than the acoustic lag of a hydraulic system.

However, this is probably academic...the switching speed of hydrauilc is obviously high enough to work just fine and, since eletromagnetic is faster, it should be fine too.

Tom.
 
Alessandro
Posts: 4962
Joined: Wed Sep 12, 2001 3:13 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Tue Mar 31, 2009 6:18 am

Did they buy the Gibraltar company or anyone knows what happened? Their system sounds very similar to me.
From New Yorqatar to Califarbia...
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus Reveals Self-Powered Landing Gear, Braking

Wed Apr 01, 2009 5:33 am



Quoting Alessandro (Reply 36):
Did they buy the Gibraltar company or anyone knows what happened?

They appear to still be around:
http://www.wheeltug.gi/

Quoting Alessandro (Reply 36):
Their system sounds very similar to me.

As far as I know, they were just driving the nosegear as a taxi-solution...they didn't play with the main gear, and didn't go for regenerative braking. I'm not even sure the chorus motor can do power generation.

Tom.

Who is online

Users browsing this forum: afterburner and 11 guests