Warbird Information Exchange

Setting aside anyone's personal feelings on TIGHAR, the U.S. Navy, etc., here's a pragmatic question- what is the impact of 60 years' immersion in saltwater on aircraft aluminum?

There are abundant Japanese aircraft near islands in the Pacific, several known American fighter and bomber wrecks in the Adriatic and around Italy, and we've all heard of repeated discoveries of German wrecks in northern waters. If someone could raise a host of those wrecks, what general condition will they likely be in? The structures I've seen in pictures look pretty solid, but are they solid enough to raise, wash off, and display as static? Could any of them be restored to flyable? (and not just a "borrow-the-dataplate" reconstruction approach)

This may be a question with numerous variables, but generally, does anyone know what value there is to raising saltwater wrecks?

Just something fun to discuss...

kevin

Umm.. i'll try to answer this to the best of my ability but there are probably people here with far more knowledge.

Other than the $$$ aspect of recovering something from sea.. the one major problem will be corrosion (and it can't easily be brushed off)
Chances are the minute the metal is exposed to air after decades under water it will turn to mush..

I've recovered (non-aviation) objects from salt water and with metals i've learnt (the hard way) that you must never let them dry out.. ideally you want to move the object under water to a container of oil.. how u can do this is possible but beyond the scope of moving a entire aircraft or even an engine thru the process.

Iron (such as engine blocks etc) will have become highly unstable and any exposure to direct oxygen will weaken them to the point that it will deform (mush).. I can go into the science of this too but it'll simply become boring..

hope this helps.

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Vintage Warbird & German WWII galleries @ http://zeeat.spaces.live.com/

Hi,

Long term exposure to a salt water environment is EXTREMELY detrimental to any aluminum. And, while I am no scientist, the issue of any metallic objects brought out of saltwater having their metallic properties changing signifigantly is true.

I will relate a short story I heard about quite some time ago about an F6F Hellcat that was recovered off the coast of California quite some back. When the airframe was exposed to fresh air, it began to oxidize quite rapidly, even with repeated flushing with fresh water. From what I heard of the story, the Hellcat basically began to disolve right before the eyes of those who recovered it.

Now, there have been airframe recoveries from salt water environments, where due to the depth of the airframe's resting place, was sufficiently deep enough to preclude extensive damage to the airframe after it was brought to the surface. The main reason, so I am told, is due to the level of oxygen at the lower depths. Eveidently, again so I am told, the oceans work in "layers" as to salinity levels and oxygen levels. Think of the ocean in a cross section and overlay a "layer map" over your cross section. The idea makes sense also from a tactical perspective in that submarines use oceanic layers to hide in with respect to sound wave transmission to and from the "hunter and the hunted" from an ultrasonic perspective.

Hope some of this helps out,

Paul

Paul, I'm afraid that the story regarding the Hellcat may have been exagerated. That particular Hellcat was sent to Pima and was on display for many years as it was recovered. It wasn't perfect but it was intact and sitting on its gear.

That Hellcat is now on display in restored condition at Pensacola.

http://broadcast.illuminatedtech.com/display/story.cfm?bp=98&sid=8004

Rick,

Ah well....like I had attempted to relate the story was related to me from a friend. And even he thought it was suspect at the time. But I can state with relative assuredness about saltwater and aluminum. I have done extensive aircraft structures work. And "unprepapred aircraft" even flyi8ng in an environment they were never intended to rot away very very readily. I say this because the airline I once worked for had more than a few 727's doing inter-island trips out of Tokyo. When those aircraft were brought back into the country for their maintenance cycle, these planes were literally rotting in areas where none of the other 727's we operated had ever experianced corrosion. So, I guess what I am saying is that even in a salt water environment, such as the inter-island trips these planes were doing...they were just going downhill at a VERY rapid pace.

Just my two cents,

Paul

Therein lies the rub. Those 727s were flying insalt laden air. The Hellcat was in 3400 ft of O2 deprived water. Salt and O2 are the corrosive.

Not to say that a plane lying shallow salt water won't corrode badly. We've all seen the pictures.

I would say that the specific alloy, metal prep, salinity, depth, and as we all have seen temperature, have a great deal to do with airframe condition after a long submersion.

I give up on this one paul!! Yea, I think it's a good Idea to pull one up and put bondo in the spar and Fly it! Just let me know so I can come and watch! What's a little corrosion?

I found the following webpage which explains the effect of alloy composition on aluminum pitting in chloride solution (saltwater). Note, that copper content is an important factor in susceptibility to pitting. It also states that type 2xxx alloys have been used in aircraft applications for 75 years and they appear to the more prone to corrosion than some of the other alloys. Besides oxygen concentration and temperature, the exact alloy composition is important.

http://www.key-to-metals.com/Article14.htm

Tulsaboy a.k.a Kevin

Check out this thread about the Malta Air Museum... http://warbirdinformationexchange.org/p ... php?t=8778

The hurricane is a static display restoration orginally recovered from saltwater (seabed)

[edit] nice pics of the hurricane's recovery at http://www.maltaaviationmuseum.com/ (other aircrafts as well)

_________________
Vintage Warbird & German WWII galleries @ http://zeeat.spaces.live.com/