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Old Feb 20, 2011, 5:43 PM   #1
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Default Smokin' the Runway

The stress on the landing gear on touch down has got to be quite severe.

A thrill to watch though...

Jehan



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Old Feb 22, 2011, 12:20 PM   #2
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The wheels/tires on these aircraft have to accelerate from 0 to 150-160 mph in a very short distance and time as your photos graphically illustrate.

A. C.
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Old Feb 22, 2011, 3:45 PM   #3
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The wheels/tires on these aircraft have to accelerate from 0 to 150-160 mph in a very short distance and time as your photos graphically illustrate.

A. C.
I guess the weight of the aircraft x the speed (momentum) shows why the 747 looks like it blew a tire compared to the MD-88!
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Old Feb 25, 2011, 6:48 PM   #4
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Actually A.C., the highest stress on the tires occurs from touchdown and throughout the braking process. The takeoff roll causes less stress and wear than even taxiing. Cool pics Jelpee, especially the 747 which you caught at the perfect moment. He was either heavy or landed a bit hard.
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Old Feb 26, 2011, 10:18 AM   #5
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Actually A.C., the highest stress on the tires occurs from touchdown and throughout the braking process. The takeoff roll causes less stress and wear than even taxiing. Cool pics Jelpee, especially the 747 which you caught at the perfect moment. He was either heavy or landed a bit hard.
Who said anything about takeoff?

A. C
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Old Feb 26, 2011, 7:37 PM   #6
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Hi A.C., I thought you were referring to aircraft acceleration. My error. Anyhow its not the tire acceleration but the sudden contact with the runway surface that causes the severe wear and smoke. A block of wood in place of a tire would probably produce more smoke even though it's rotational momentum is zero and it's accelleration negative. Efforts to spin up the tires to approximate the rpm they would have at the moment of landing have been tried in the past with little benefit achieved as regards tire life.
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Old Feb 27, 2011, 12:53 PM   #7
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The only acceleration I had in mind was the wheel/tire acceleration from 0 RPM (airborne) to whatever RPM was required by the velocity of the aircraft at touch down and the attendant slippage (hence smoke) in that process.

I was about 12 when I asked my dad why weren't the wheels/tires pre-accelerated for landing and his answer was that it had been tried and it didn't work very well. That the method didn't reduce overall wear is understandable since the spin-up of the wheels is using up the energy of the aircraft that would otherwise be dissipated through braking which, of course also ends up heating/wearing the tires.

A. C.

Last edited by ac.smith; Feb 27, 2011 at 12:57 PM.
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