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Author Topic: plane found underwater after 34 years  (Read 11110 times)

richie conroy

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Ric Gillespie

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Re: plane found underwater after 34 years
« Reply #1 on: October 27, 2011, 01:53:28 PM »

The structure appears to be in rather good condition.  What makes it hard to recognize is the marine growth that obscures the shape.  Most marine growth relies on sunlight - the shallower the depth, the more growth.  Sunlight penetrates to about 300 meters (984 feet). This aircraft is at 105 meters (344 feet) so there's still plenty of light.  The wreckage of the Earhart aircraft is probably much deeper.

Here is an example of an aircraft in a tropical Pacific coral reef environment at a depth of only 120 feet that has been submerged for almost as long the Electra. It is still intact and easily recognizable.

The factor that is most likely to obscure wreckage of the Electra is not marine growth but "talus" (silt, sand, and coral chunks) that have accumulated on the lower parts of the reef slope over the years.
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richie conroy

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Re: plane found underwater after 34 years
« Reply #2 on: October 27, 2011, 05:07:48 PM »

but surely the constant currents that hit the reef, like the rope in the videos!!! no organisms could stick to it as they would be continua-sly washed off in theory,

also if the Electra is deeper than 300 meters it should be in the condition it entered that depth correct ?
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Ric Gillespie

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Re: plane found underwater after 34 years
« Reply #3 on: October 27, 2011, 05:56:32 PM »

but surely the constant currents that hit the reef, like the rope in the videos!!! no organisms could stick to it as they would be continua-sly washed off in theory,

We don't know how long the rope has been there but underwater Norwich City doesn't have a lot of marine growth on it and it has been there since the stern end of the ship broke off in 1939.

also if the Electra is deeper than 300 meters it should be in the condition it entered that depth correct ?

Correct - in theory.
« Last Edit: October 27, 2011, 09:05:07 PM by Martin X. Moleski, SJ »
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Anthony Allen Roach

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Re: plane found underwater after 34 years
« Reply #4 on: July 09, 2012, 12:30:57 PM »

I agree with Mr. Gillespie.  The condition of an aircraft in the water depends on the type of water (saltwater and fresh) and the depth.  The depth seems to control the growth of organisms on the structure.

When I worked at the San Diego Aerospace Museum, our team was restoring an F4F Wildcat.  The Wildcat had been recovered from Lake Michigan, where it had crashed during pilot training in 1942.  We were working on it 56 years later.  Some of it was in bad condition (as a result of the recovery and other attempts from amateurs to recover it) and some of it was in surprisingly good condition.  Obviously, it had been sitting in cold fresh water, instead of salt.

The areas on the Wildcat that had the least amount of corrosion and damage were areas that had liberal application of zinc chromate primer, or were protected with cellophane tape during its original construction.  Places where two different metals met were the most corroded, except where some assembly line worker had lovingly applied cellophane tape.  I remember one assembly shown to me by a fellow who had worked for Grumman during the war.  "See that," he said, showing me cellophane tape over an assembly that had very little corrosion.  "Somebody built this thing knowing that someone's son or husband would be flying it.  They knew the pilot's survival may depend on the durability of what they were constructing.  No one builds stuff like this anymore."

It brought tears to my eyes.
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Jeff Victor Hayden

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Re: plane found underwater after 34 years
« Reply #5 on: July 09, 2012, 01:05:39 PM »

Quote
Places where two different metals met were the most corroded, except where some assembly line worker had lovingly applied cellophane tape
Totally correct Anthony...
Deposition Corrosion
In designing aluminum and aluminum alloys for satisfactory corrosion resistance, it is important to keep in mind that ions of several metals have reduction potentials that are more cathodic than the solution potential of aluminum and therefore can be reduced to metallic form by aluminum. For each chemical equivalent of so-called heavy-metal ions reduced, a chemical equivalent of aluminum is oxidized. Reduction of only a small amount of these ions can lead to severe localized corrosion of aluminum, because the metal reduced from them plates onto the aluminum and sets up galvanic cells.
The more important heavy metals are copper, lead, mercury, nickel, and tin. The effects of these metals on aluminum are of greatest concern in acidic solutions; in alkaline solutions, they have much lower solubilities and therefore much less severe effects


http://www.keytometals.com/page.aspx?ID=CheckArticle&site=ktn&NM=187

Steel, stainless steel, copper and other alloys also, to a lesser extent, contribute to deposition corrosion and, the best catalyst for the processs? sodium chloride.
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Matt Revington

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