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AF 447 Search to resume (part2)

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AF 447 Search to resume (part2)

Old 27th Apr 2011, 23:15
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The 777 is a 737 on steroids.
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Old 27th Apr 2011, 23:22
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HF antenna

It is not the main subject, but somebody is interested in the aerial for décametric waves, here is some information and a photo of the leading edge of VS.

One of the recorders is located in the rear part of the plane.

Last edited by Jetdriver; 28th Apr 2011 at 01:29.
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Old 27th Apr 2011, 23:32
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Raw data please, not your TV brand !
We are curious here ...

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Old 28th Apr 2011, 00:49
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Originally Posted by TOM57
BEA says that the area where the plane was found had been researched in the early phases by sonar. Nothing was detected then, and that is why they had privileged other sectors in later searches.
While this isn't directly pertinent to the subject, I've got to say that there's major irony there. When the joint French/US team went looking for the Titanic in 1985, their starting point was the last sonar return not explored by Jack Grimm's expedition. As soon as the sonar scan started, the returns were so wild that they figured it must be a technical malfunction and brought the sonar device back up for recalibration. They then proceeded to spend weeks scanning the rest of the search area, finding nothing. It later transpired that while the sonar readings were fluctuating wildly at the beginning of the mission, some of the returns were true and they were in fact practically on top of the wreck site. Every pass they made in the following weeks took them further and further away from the target.

The US half of the team (having been away on what turned out to be a clandestine mission to film the USS Thresher and Scorpion) then put all their chips on sending the video cameras down at the starting point and found the wreck site with barely a couple of days to spare.

Deep-ocean exploration and salvage - possibly one of the hardest things in the world to get right!
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Old 28th Apr 2011, 00:49
  #225 (permalink)  
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infrequent, captain scott

"lingue en bouche, s'il vous plait..."

Tongue in cheek. I don't believe in faked evidence, avoiding duty, stolen flight recorders, check that last......

I believe in bias, corporate and political games, and advantaging one's friends. Not outright criminal, ok?? Until it is past time, friends get the benefit of the doubt, mine do, how about yours??

guppies that rupture after going deferred for five thousand cycles??

Mon Dieu!! Pitots that freeze and tell lies??? How many times was that, you know, before 228 people died and the pilots did a labor action?? Now listen, I believe in scepticism, harsh and unabashed. There are no mistakes in aviation, not lately. What gets trumpeted as "bad luck" is some butthole with a calculator convincing the Board it's ok to stretch service life, and hire students for complicated machining. Rudder jacks freeze, Computers go bananas, and people die. Pretending we're still at some frontier in a desperate game with physics is nonsense, we can make and fly aircraft that are levels above the current iteratae, and make a living too. Playing the fools game with wizards who do this s..t for a living is not productive.....Other than that, it is nice to see so many people still interested in this drama; I believe it may be a modern record.

Don't order the chicken pot pie........
 
Old 28th Apr 2011, 00:58
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Originally Posted by bearfoil
infrequent, captain scott

"lingue en bouche, s'il vous plait..."

Tongue in cheek. I don't believe in faked evidence, avoiding duty, stolen flight recorders, check that last......

I believe in bias, corporate and political games, and advantaging one's friends. Not outright criminal, ok?? Until it is past time, friends get the benefit of the doubt, mine do, how about yours??

guppies that rupture after going deferred for five thousand cycles??

Mon Dieu!! Pitots that freeze and tell lies??? How many times was that, you know, before 228 people died and the pilots did a labor action?? Now listen, I believe in scepticism, harsh and unabashed. There are no mistakes in aviation, not lately. What gets trumpeted as "bad luck" is some butthole with a calculator convincing the Board it's ok to stretch service life, and hire students for complicated machining. Rudder jacks freeze, Computers go bananas, and people die. Pretending we're still at some frontier in a desperate game with physics is nonsense, we can make and fly aircraft that are levels above the current iteratae, and make a living too. Playing the fools game with wizards who do this s..t for a living is not productive.....Other than that, it is nice to see so many people still interested in this drama; I believe it may be a modern record.

Don't order the chicken pot pie........
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Old 28th Apr 2011, 01:32
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dozy

Take everything you see and read with a grain or more of salt.

Happy skies.
 
Old 28th Apr 2011, 01:40
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Translation from Le Monde

Detached by the Impact

"It was surrounded by debris belonging to other parts of the airplane" added the BEA [informant]. "The protected container or memory module is normally attached to the chassis. But this module is much heavier than the chassis. No doubt it came apart from the impact" with the surface of the water, explained to AFP the Director of BEA, Jean-Paul Troadec. "The container has a much greater force of inertia, it is quite possible that the container followed a different descent trajectory than that of the châssis because of currents", he explained further.
Sounds perfectly reasonable to me.

I would propose obtaining a similar recorder and memory module to chuck over the side to see where they end up -- how far apart and bearing would be useful.

Well it would be considerably cheaper to remove the expensive innards of the boxes, add pingers and ballast to bring the weight back to spec before chucking overboard Don't forget to bend the chassis frame the same as the original.
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Old 28th Apr 2011, 01:46
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Graybeard: The 777 is a 737 on steroids

I'm not too sure what you mean by that. The B777 is certainly a big aircraft, but the fly by wire gizmos make it a very benign flying machine, with far better handling characteristics than a B737. Boeing got the B777 right, straight out of the box, and were quite right IMHO to leave ultimate control in the hands of the pilot, not a possibly deluded box of tricks.
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Old 28th Apr 2011, 01:58
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Bearfoil... one day, the bean counters will understand the costs of an accident exceed the costs of safety.
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Old 28th Apr 2011, 02:12
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777

Sorry, 777Fly. I meant, on the ramp, the 777 "looks like" a 737 on steroids. My post followed another along the same line.
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Old 28th Apr 2011, 02:32
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Cool

Hi,

it is quite possible that the container followed a different descent trajectory than that of the châssis because of currents", he explained further.
This does not seem to bode well .. if BEA has again evoked currents ....
We know what happened with the study thereof in other phases of research ....
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Old 28th Apr 2011, 03:36
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I really hope they do retrieve back to the ship the FDR chassis.

Can you imagine letting it on the deep, and by some unfortunate coincidence the memory module is actually inside the chassis?

The last place they would expect!

Now really, it's a serious professional investigation, I'm sure they spent at least an hour of the 12 hour of the first dive circling and moving the FDR chassis.
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Old 28th Apr 2011, 05:28
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Le Chassis

Two pictures.
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Old 28th Apr 2011, 05:39
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Originally Posted by gums
OTOH, fer jeeez friggin' sake!!!!! The "memory" is not encased in a stainless steel/titanium "crash survivable" container - like the the DFDR itself, and is attached to the OUTSIDE of the neat, orange qizmo!?! BEAM ME UP!!!!

OK, the memory module is what is packaged to survive the apocalypse. The rest is the electronics that feed that little bit of memory. If the memory module sticks to the chassis that is nice. If it breaks loose there was enough stress that it might have broken rather than come off whole if it had been secured better.

Come to think of it, if the memory module separates easily it cannot get corrupted by the death spasms of the electronics module. It may have been designed to detach fairly easily for that reason.

Wikipiddle has some pictures that might help you see what is going on. But the one shown with three main pieces should do it, electronics chassis, memory module, and pinger.
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Old 28th Apr 2011, 05:51
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NeoFit, thanks lots for that picture. It clear up just a whole lot.

I'd not call that a slot antenna. There's no slot. It function as a form of loop antenna with part of the wire really wide and the other part merely wide. It would be relatively low loss at RF. And the feed point impedance is apparently .035 ohms. I wonder if the conductors are silver plated for best efficiency. That's into a region that ought to match and work pretty well. (And it appears it's short enough resonance is not an issue until fairly high frequencies 15-20MHz.) As a loop it MAY favor radiation to the sides, though. That may not be good. the good thing for it being a loop is it's virtually immune to static electricity.

Anyway - thanks for the picture. It clarified for me "where the current is going."
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Old 28th Apr 2011, 06:00
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If the "beer can" is much denser than the chassis, they should look back to the East of the Chassis location to have a hope of finding it. At the surface, the two items were initially together. As they settled to the bottom, the lighter chassis took longer to fall and was carried further to the West. We are about to see a practical application of the density sorting concept.

From the internal description that MM43 provided a link to, you have the memory chips surrounded by a thermal mass, which is then surrounded by insullation, which is then surrounded by an armoured shell. So why are the attaching feet on the memory module so small? It looks like a few whacks with a hammer would break them. The pinger module also looks like it could easily be sheared off the memory module. It really seems that they took weight savings to a ridiculous extreme in designing the unit and now it is a problem. As accident impacts go, the AF447 impact with the surface was relatively light.
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Old 28th Apr 2011, 07:23
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Can you have 'loose silt' under that pressure of water ? Even the engines weren't that dug in. Gives hope for finding the parts.
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Old 28th Apr 2011, 09:10
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Originally Posted by Mr Optimistic
Can you have 'loose silt' under that pressure of water ? Even the engines weren't that dug in. Gives hope for finding the parts.

Theoretically you could have. The pressure applies on all sides where it touches an object. As the individual sand particles are not sealed watertight the pressure will also apply from below.
However, I agree it looks that the bottom is rather solid. The debris shown so far in the images is not buried at all. Especially even the heavy items like engines, gears etc.
So I'm also confident that the memory module hasn't been buried significantly.
On the other hand I'm also a bit at a loss why design a nice bright orange box of very specific shape and then loosely attach the important part as a rather small unremarkably shaped can onto it instead of including it into the box making the latter somewhat bigger and thereby even more easy to find !???
Somehow I have difficulties seeing the rationale behind it...
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Old 28th Apr 2011, 09:22
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Does seem odd that you have a nice big brightly painted orange box to help location, and then accept that the memory may depart company over differing 'inertias'. Still, presume its a standard design and there must be a reason. On the pressure issue, way I looked at it was if you put the sand in an isostatic press and applied pressure from all sides you would expect the grains to lock. Still, I have been wrong before !
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