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Airbus Reveals Self-Powered Landing Gear, Braking  
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Posted (5 years 6 months 1 week 4 days 18 hours ago) and read 6993 times:
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....From FlightGlobal:

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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.

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Full article here.

2H4


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37 replies: All unread, showing first 25:
 
User currently offlineTristarSteve From Sweden, joined Nov 2005, 4017 posts, RR: 34
Reply 1, posted (5 years 6 months 1 week 4 days 17 hours ago) and read 6932 times:

It looks like the PR dept released this a week early.  biggrin 

User currently offlineVzlet From United States of America, joined Mar 2004, 835 posts, RR: 0
Reply 2, posted (5 years 6 months 1 week 4 days 16 hours ago) and read 6904 times:

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
User currently offlineLemmy From United States of America, joined Dec 2004, 258 posts, RR: 0
Reply 3, posted (5 years 6 months 1 week 4 days 14 hours ago) and read 6807 times:

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 ...
User currently offlineKELPkid From United States of America, joined Nov 2005, 6398 posts, RR: 3
Reply 4, posted (5 years 6 months 1 week 4 days 13 hours ago) and read 6779 times:



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 :-)
User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 5, posted (5 years 6 months 1 week 4 days 11 hours ago) and read 6687 times:

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.


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User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 6, posted (5 years 6 months 1 week 4 days 11 hours ago) and read 6682 times:
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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



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User currently offlineRJ111 From , joined Dec 1969, posts, RR:
Reply 7, posted (5 years 6 months 1 week 4 days 11 hours ago) and read 6662 times:

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.


User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 8, posted (5 years 6 months 1 week 4 days 11 hours ago) and read 6656 times:



Quoting 2H4 (Reply 6):
treadmill

Excellent. Anet solves yet another aviation quandry.



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User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 9, posted (5 years 6 months 1 week 4 days 10 hours ago) and read 6644 times:



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.
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 10, posted (5 years 6 months 1 week 4 days 10 hours ago) and read 6639 times:
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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 currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 11, posted (5 years 6 months 1 week 4 days 10 hours ago) and read 6620 times:

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.
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 12, posted (5 years 6 months 1 week 4 days 8 hours ago) and read 6566 times:



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.


User currently offlineTSS From United States of America, joined Dec 2006, 3068 posts, RR: 5
Reply 13, posted (5 years 6 months 1 week 4 days 6 hours ago) and read 6542 times:

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!
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 14, posted (5 years 6 months 1 week 4 days 4 hours ago) and read 6518 times:



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.


User currently offlineRwessel From United States of America, joined Jan 2007, 2353 posts, RR: 2
Reply 15, posted (5 years 6 months 1 week 4 days 3 hours ago) and read 6495 times:
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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...


User currently offlineRheinwaldner From Switzerland, joined Jan 2008, 2241 posts, RR: 5
Reply 16, posted (5 years 6 months 1 week 4 days 1 hour ago) and read 6455 times:



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 currently offlineDocLightning From United States of America, joined Nov 2005, 19807 posts, RR: 59
Reply 17, posted (5 years 6 months 1 week 3 days 17 hours ago) and read 6258 times:



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!


User currently offlineDaBuzzard From Canada, joined Sep 2007, 136 posts, RR: 0
Reply 18, posted (5 years 6 months 1 week 3 days 13 hours ago) and read 6138 times:



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

Shhhh, maybe no one noticed.....  crossfingers 


User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 19, posted (5 years 6 months 1 week 3 days 9 hours ago) and read 6016 times:



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.
User currently offlineSEPilot From United States of America, joined Dec 2006, 6924 posts, RR: 46
Reply 20, posted (5 years 6 months 1 week 2 days 13 hours ago) and read 5796 times:

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
User currently offlineOnetogo From United States of America, joined Feb 2006, 314 posts, RR: 0
Reply 21, posted (5 years 6 months 1 week 2 days 10 hours ago) and read 5711 times:

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.

User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Reply 22, posted (5 years 6 months 1 week 1 day 19 hours ago) and read 5592 times:



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?


User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 23, posted (5 years 6 months 1 week 1 day 17 hours ago) and read 5554 times:



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.



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User currently offlineDocLightning From United States of America, joined Nov 2005, 19807 posts, RR: 59
Reply 24, posted (5 years 6 months 1 week 13 hours ago) and read 5328 times:

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.


25 ZANL188 : 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 ai
26 DocLightning : 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
27 SEPilot : 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 pl
28 ZANL188 : ... 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
29 Post contains links ZANL188 : 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.... http://www.youtube
30 SEPilot : 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
31 Tdscanuck : 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.
32 DocLightning : 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
33 SEPilot : But it would be much, much heavier to achieve the same braking force. This is a total non-starter for aircraft.
34 ZANL188 : I have wonder how an electromagnet braking system would handle antiskid? Seems to me it would lack the fine control necessary....
35 Tdscanuck : In theory, the reaction time of an electromagnetic brake could be faster than a hydraulic...the cycle time of an electromagnetic brake is just limite
36 Alessandro : Did they buy the Gibraltar company or anyone knows what happened? Their system sounds very similar to me.
37 Post contains links Tdscanuck : They appear to still be around: http://www.wheeltug.gi/ As far as I know, they were just driving the nosegear as a taxi-solution...they didn't play w
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