A380 MLG Tire Scuffing/Skidding
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A380 MLG Tire Scuffing/Skidding
I received this last night. Anyone know what is going on here and please don't shoot the messenger!
Sorry but you'll have to click on the links below to see the photos that came with the email message.
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For those of you who aren't passingly familiar with what this is all about ... someone was trying to turn AirBus' great big, brand-new, A380 aircraft a little too sharply (we don't know whether under it's own power, or while it was under tow).
AirBus elected NOT to make their main landing gear system (four separate gear with four wheels apiece) steerable. Why? You save a considerable amount of weight -- not to mention some serious extra cost -- by not doing so. There is a trade-off, however ...
When you have non-steerable gear that are configured like they are on this aircraft, you have scuffing/skidding going on whenever you turn the aircraft. This isn't an unusual design for a wheeled vehicle, though. For instance, a dual-axle semi-trailer does the same thing when it's being maneuvered sharply within a warehouse parking lit. What makes the A380 so special, is the incredible amount of weight on each huge tire, in conjunction with the widely-spaced gear. In concert, these two aspects considerably magnify the inherent problem -- to the point where the asphalt (not just the rubber tire) is taking it in the shorts ... not to mention the stress and overload that's happening to the entire structure between the tire and the gear attaching points in the wing structure. Note the apparent bending of the gear in one of the shots! No, Mildred, that is NOT a good thing to be happening to your aircraft's main landing gear. Unless they're making everything out of rubber, those stress loads have GOT to be off the scale!
As new-aircraft design problems go, this will likely prove to be a very expensive one for AirBus to deal with. It's either that, or the aircraft will only be able to operate in and out of airports that have the extra fifty-acres it will need to get safely turned-around. It'll be interesting to see how they solve this one.
Sorry but you'll have to click on the links below to see the photos that came with the email message.
=================
For those of you who aren't passingly familiar with what this is all about ... someone was trying to turn AirBus' great big, brand-new, A380 aircraft a little too sharply (we don't know whether under it's own power, or while it was under tow).
AirBus elected NOT to make their main landing gear system (four separate gear with four wheels apiece) steerable. Why? You save a considerable amount of weight -- not to mention some serious extra cost -- by not doing so. There is a trade-off, however ...
When you have non-steerable gear that are configured like they are on this aircraft, you have scuffing/skidding going on whenever you turn the aircraft. This isn't an unusual design for a wheeled vehicle, though. For instance, a dual-axle semi-trailer does the same thing when it's being maneuvered sharply within a warehouse parking lit. What makes the A380 so special, is the incredible amount of weight on each huge tire, in conjunction with the widely-spaced gear. In concert, these two aspects considerably magnify the inherent problem -- to the point where the asphalt (not just the rubber tire) is taking it in the shorts ... not to mention the stress and overload that's happening to the entire structure between the tire and the gear attaching points in the wing structure. Note the apparent bending of the gear in one of the shots! No, Mildred, that is NOT a good thing to be happening to your aircraft's main landing gear. Unless they're making everything out of rubber, those stress loads have GOT to be off the scale!
As new-aircraft design problems go, this will likely prove to be a very expensive one for AirBus to deal with. It's either that, or the aircraft will only be able to operate in and out of airports that have the extra fifty-acres it will need to get safely turned-around. It'll be interesting to see how they solve this one.
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If those pictures are real then I cannot believe that this damage was caused simply by lateral scuffing in a turn. It looks much more like the results of a high-speed skid on landing; those wheels have gone almost 90 degrees sideways, for goodness sake!
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You wouldn't want to find that on the walkround!
Looks to me like a pushback - those are the wing gear (4 wheels). The 747 wing gear do not turn either - it's the body gear that turns. Perhaps the weight penalty and complexity is too great for wing gear to swivel?
Skid angle looks about 60 deg... hope they scrapped the tyres....
Cheers, TP
Looks to me like a pushback - those are the wing gear (4 wheels). The 747 wing gear do not turn either - it's the body gear that turns. Perhaps the weight penalty and complexity is too great for wing gear to swivel?
Skid angle looks about 60 deg... hope they scrapped the tyres....
Cheers, TP
Ut Sementem Feeceris
I agree with Seloco. I don't believe they are the result of a normal turn / pushback. It's even gouged the tarmac!
Mind you, on a second look if the tug had got to 90° for a "tight" push , then it's not inconcievable that the bogey on the inside of the turn would scuff. That is what it looks like on the first picture which appear to show the inner (turn) bogey pictured from the front.
I hope someone hasn't made a monumental 8all5 up at the design stage.
A4
Edited after second look at pics.
Mind you, on a second look if the tug had got to 90° for a "tight" push , then it's not inconcievable that the bogey on the inside of the turn would scuff. That is what it looks like on the first picture which appear to show the inner (turn) bogey pictured from the front.
I hope someone hasn't made a monumental 8all5 up at the design stage.
A4
Edited after second look at pics.
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One rather large problem for Airbus if this is as originaly decribed.
Making the gear steerable at the back would seems to be a must and plain common sense on an aicraft this size. But, you can bet they did not make them steerable to save weight, considering the thing is overweight as it is.
Have they perhaps shot themselves in the foot on this one? and if this is not connected to the recent announcement about the delaying of deliveries for 6 months... how much longer do you think it will delay the aircraft? And how much longer are the customers going to wait?
Making the gear steerable at the back would seems to be a must and plain common sense on an aicraft this size. But, you can bet they did not make them steerable to save weight, considering the thing is overweight as it is.
Have they perhaps shot themselves in the foot on this one? and if this is not connected to the recent announcement about the delaying of deliveries for 6 months... how much longer do you think it will delay the aircraft? And how much longer are the customers going to wait?
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Assuming, of course, that these are genuine pictures...................?????????
They depict the outer gear of the a380 scuffed and buckled.
IMO, these are genuine photos... the quality is just too good for fakes.
But, if they are fakes, then of what aircraft are they?
I know of no other aircraft with 6 wheel bogies under the fuselage and 4 wheel bogies under the wing.
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The pictures might well be genuine - perhaps from a test?
However, the story of the original poster is certainly not genuine, just too many factual errors in it.
Four gears with four wheels? If I'm not completely blind then I count 6 six wheels under the body gear. Not steerable? As far as I know the body landing gear is steerable, it's the 4-wheeled wing gears that aren't. But then I'm no aircraft engineer and when someone thinks that Airbus and Goodrich (they're actually building the gears) got it all wrong ...
However, the story of the original poster is certainly not genuine, just too many factual errors in it.
AirBus elected NOT to make their main landing gear system (four separate gear with four wheels apiece) steerable.
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What makes the A380 so special, is the incredible amount of weight on each huge tire
I'm sure the photos are of a test. Remember when they landed a A340-600 at over MTOW? Almost destroyed the MLG....but the a/c survived.
Last edited by BahrainLad; 14th Jul 2005 at 21:23.
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I would venture (based on the fact the aircraft is in a testing phase) that this is a test. Whether it passed or not depends on what the parameters were. For my money it passed. The tyres are still on the rims, none appear to be deflated and despite the tear on the tarmac it is relatively minor for the weight of the aircraft.