Air France 447 - On topic only!

[Evan]

A unit cannot have 'bouyancy at some depth' unless it is compressible, as bouyancy is determined by weight of the volume of seawater or other fluid displaced compared to the weight of the unit, if the weight of the unit is heavier than the weight of the volume of fluid displaced, it will sink. All things being equal, with no shape deformity due to pressure crushing, then bouyancy at 10 feet is the same as bouyancy at 1000 feet.
Then the interesting calculation is how much negative bouyancy, if, say, 3 kg, then the unit will effective weigh 3 kg in water, but will sink at a rate caused by it's shape properties - if it was long and flat or wingshaped it could adopt of form of glide, but being a cyclinder, it should sink in a fairly controlled and predictable way.

What I mean is that, a sealed cylinder containing air might have some buoyancy as it sinks and not sink at the same rate as, say, a turbofan or a large piece of fuselage which has no buoyancy, and might therefore be more susceptible to currents and carried along to a different place on the ocean floor. If it separated on impact with the ocean, I would not expect to find it amongst the bulk of the wreckage.

[Highkeas]

What I mean is that, a sealed cylinder containing air might have some buoyancy as it sinks and not sink at the same rate as, say, a turbofan or a large piece of fuselage which has no buoyancy, and might therefore be more susceptible to currents and carried along to a different place on the ocean floor. If it separated on impact with the ocean, I would not expect to find it amongst the bulk of the wreckage.

What you say is correct - descent rate depends on it ballistic ratio (W/CdA) just as it would in air. That is probaly why the debris pattern is the way it is (not to mention that there may have been some above water dispersion of debris upon impact).

[ultraflight]

I wonder why they paint the casing orange while it can be separated from the memory module, which is probably camouflage green.. or is it a bit like those Russian puppets, shell upon shell for protection?

[Highkeas]

I wonder why they paint the casing orange while it can be separated from the memory module, which is probably camouflage green.. or is it a bit like those Russian puppets, shell upon shell for protection?

In my experience all non-flight critical boxes and wiring is orange (at least on flight test aircraft).

The data module is also orange (with a big white label according to the picture in post #533).

[Jason]

FDR found & lifted

Good news:

They found and lifted the FDR!

http://www.bea.aero/fr/enquetes/vol.af.447/info01mai2011.en.php

Impressive how clear the pictures are.

[AVION1]

great news..!
The robot finally found it and grabbed it, as you can see in this picture!

[Deadstick]

Great news! Soon we'll have some solid facts on what occurred.

[AVION1]

Great news! Soon we'll have some solid facts on what occurred.

We hope the memory chip is fine....!!, I heard it is already in the hands of BEA at the recovery ship.

[Evan]

Hopefully they can locate the CVR as well. It might be more revealing than the FDR, particularly with regard to situational awareness. Isn't the CVR installed in the same area of the fuselage?

[Gabriel]

great news..!
The robot finally found it and grabbed it, as you can see in this picture!

I can confirm that it doesn't float, Evan.

[Gabriel]

I was very pessimistic about them finding the wreckage at the bottom of the sea, let alone the FDR.

Now that they did it and that the CSM is in so very good shape, I'm very optimistic that the data will be Ok. Amazing that it's gone through a plane crash plus two years that the deepest bottom of the sea. It looks like it could have survived another hundred years there.

[AVION1]

Hopefully they can locate the CVR as well. It might be more revealing than the FDR, particularly with regard to situational awareness. Isn't the CVR installed in the same area of the fuselage?

No, the CVR is installed just behind the wings, and the FDR in the tail.

[decker1993]

I looked it up, both CVR and FDR are located in the tail section of planes. This maximize the likelihood of its survival in a crash.

[Myndee]

I am happy! Today is a good day. They found the memory module, Osama is gone, I am getting thunder and rain at my place, my personal life situation is improving, and did I mention that the US Military kicks ass? May is starting off very nicely!!!

We pretty much know how the sequence went. At least we will be able to see how it started. Sure hope they find the CVR.

[Highkeas]

For anyone interested in the FDR I found this Honeywell FDR description - it looks like a different model than the one recovered from AF447.

http://www51.honeywell.com/aero/common/documents/Flight_Data_Recorder_(SSFDR).pdf