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AF 447 Search to resume (part2)

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AF 447 Search to resume (part2)

Old 13th May 2011, 03:06
  #1281 (permalink)  
bearfoil
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takata #1216

Jackscrew, APU, FDR, CVR. etc. very tight zone, and an unmarked piece that looks like the THS right in there, a bit longer than an engine in length, (it should be almost thrice as long if intact), and one cannot disregard what looks like a substantial amount of smaller debris in the area of the identified contents of the tail. As large as the piece appears, it looks like it deserves some ID, as the cockpit parts are likewise bunched, and labelled ?? The main spar(s) of the THS would be almost as stout as the main spar of the wings, so I'm not sure the THS would completely disappear. Like the wings, the strongest parts (to include the box) would remain.
 
Old 13th May 2011, 03:18
  #1282 (permalink)  
 
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Engine Photos

Chris,

The original photos (two) taken on the sea bed are of the same engine, slightly different angle of the photos, one to the other, IMO.

The photo of the engine being hoisted aboard ship is the other engine, not the one on the sea bed, IMO. The notable difference appears in the area of the LPT case. The one on the sea bed appears to have the rear part of the case missing exposing the last stage or stages of turbine blades. The one on board ship has a rather intact LPT case with major damage only to the turbine rear frame from the photographed area.
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Old 13th May 2011, 03:35
  #1283 (permalink)  
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If she was rotating (either direction), and had not enough D/S to keep from occasionally "falling" tail first, the tail would have dug in with its APU first, shed the VS, and then lost engines as the forward fuselage "flipped" over the top, the cockpit describing a large arc over the Wing center box to plant behind the engines. This means a heading at impact of ENE, and accounts for the position of all the parts, odd though it may sound....To be correct, this would need BEA's aspect at impact. it also requires more than a little horizontal and less vertical.
 
Old 13th May 2011, 04:00
  #1284 (permalink)  
 
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Strange location of some pieces on debris field

Bear,

Another model:

Sea currents dragging to W the light pieces, the bigger (not denser) and the ones with "water braking shape"

This can explain strange location of some parts.

But there are some other exceptions: APU, boxes, THS jackscrew. For this i could imagine rear section of a/c passing over the fuselage. 1)"bouncing" 2) breaking frames due APU mass and THS fuel and "falling" ahead.

For LH MLG/wing parts i have another hypothesis when this wing broke wit a/c tail yaw to port.

Conjectures...


Edit#1:

Both MLG traveled farther due it´s inertia and some aerodynamic due parts of wing still attached. This could explain location of both MLG. The LH aligned with fuselage and RH farther to south with "distorted trajectory" due a/c yaw and perhaps RH wing "ground effect" air disturbance.

Obs. The debris shape IMO is mostly due sea currents. With the coincidence of a/c with near the same trajectory (with also about the same heading when impacted water) tail yawing to port side.

Last edited by Jetdriver; 14th May 2011 at 21:14.
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Old 13th May 2011, 05:32
  #1285 (permalink)  
 
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If she was rotating (either direction), and had not enough D/S to keep from occasionally "falling" tail first, the tail would have dug in with its APU first, shed the VS, and then lost engines as the forward fuselage "flipped" over the top, the cockpit describing a large arc over the Wing center box to plant behind the engines. This means a heading at impact of ENE, and accounts for the position of all the parts, odd though it may sound....To be correct, this would need BEA's aspect at impact. it also requires more than a little horizontal and less vertical.
This explaination occured me. If she was rotating, heading at impact becomes purely coincidental. Also, for the cockpit to describe the arc you are suggesting we would be talking pretty significant torque from the rotation.
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Old 13th May 2011, 05:41
  #1286 (permalink)  
 
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auv-ee, gee, thanks for the numbers. They strongly suggest the 1700 meters range quote would be extraordinarily conservative. We start with 160.5 dBpa* at 1 meter and end at 30 dBps (18dBpa + some serious margin). That's 130dB of attenuation needed. Apparently we can expect 10dB from the properties of water. So that's a million to 1 range distance ratio before it's not detectable. Somehow I do not think the surface falls outside a thousand km from the emitter since the depth is single digit km.

3900 meters to 300 meters is 3600 meters. Call it 4000 meters and allow some modestly generous slant range. (That's nearly 2000 meters wide swath at the surface. 888*2 actually.) That would be 72dB loss or a level of about 88dBps looking at a 30dBpa threshold. Somehow a nearly 60 dB above threshold signal should blow the sonar operator out of his seat if he could hear it.

So unless somebody introduces new loss sources I withdraw my comments about the submarine not having a chance of hearing the pingers. And I start wondering what in heck happened to them that they BOTH failed to work.
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Old 13th May 2011, 05:50
  #1287 (permalink)  
 
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Originally Posted by bearfoil
... and do NOT presume to tell me what I think.
At the risk of becoming very unpopular here this cyberunit wonders if there even IS thinking present at all. There must be as the postings are at least grammatical.
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Old 13th May 2011, 05:58
  #1288 (permalink)  
 
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Lemurian - consider also currents encountered during sinking and random walk spreading as the lighter debris settles. You MIGHT be able to draw some rough conclusions if you assume heavy items sank near straight down. But that's not even accurate. If the plane was making headway, even something modest like 60 mph (statute) then a one second difference in time the engines broke loose would lead to an 88' difference in starting point. And indications are that one wing was lower than the other in addition to the indications of at least a small amount of horizontal velocity component.

If one wing was lower that wing's engine would strike early, toss the plane around a bit, alter the horizontal velocity component of the second engine which then breaks away when it strikes the water.

<shrug> It's all not quite random. But there are too many variables to say much of anything other than that the plane seems to have broken up semi-symmetrically. That maybe supports the presumed attitude upon striking the surface.
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Old 13th May 2011, 10:17
  #1289 (permalink)  

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consider also currents encountered during sinking and random walk spreading as the lighter debris settles. You MIGHT be able to draw some rough conclusions if you assume heavy items sank near straight down. But that's not even accurate. If the plane was making headway, even something modest like 60 mph (statute) then a one second difference in time the engines broke loose would lead to an 88' difference in starting point.
Too many variables. Too many unknowns." Precisely.
The field is so concentrated that the currents weren't very strong, were they ?
On another thread, someone posited that two items, one sinking to the bottom in 15 minutes, the other taking 30 mins, in a ONE KNOT CURRENT, they will be separated by 1500 ft at their resting places.
That figure is strikingly close to the dimensions of the debris field, don't you agree ?
Of course I would think that quite a few pieces would have *drifted*,falling leaves-style to tha bottom, hence the *random* pattern we could observe.

Of course I might be all wrong.

Last edited by Jetdriver; 14th May 2011 at 21:19.
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Old 13th May 2011, 11:06
  #1290 (permalink)  
 
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Pour on s'amuser avant le déluge imminent...

Lemurian,

Notwithstanding JD-EE's and PJ2's slightly gloomy, if realistic, comment above, I think we should continue our speculative discussions right up to the eagerly-anticipated dénouement. "Too many variables" and "too many unknowns" have not discouraged the PPRuNe population (PJ2 included) from two years of almost uninterrupted proposals and counter-proposals.

Don't suppose I'm the only one to have learned an enormous amount from the fascinating and informative contributions of the many knowledgeable, intelligent forum-ites here (bearfoil not excepted), and the cut and thrust of argument has always concentrated the mind.

At this stage, we have suddenly received a bigger averse of data than anything since July 2009. It would be against the spirit of this forum for us to be overawed by the imminent prospect of a déluge of data from the recorders. This promises to trash most of our cherished theories, but that does not necessarily discredit their validity as hypotheses. The post-result learning process will have more relevance and immediacy for us if we shall have kept pushing on to the very last.

Happy holiday, PJ2!
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Old 13th May 2011, 14:05
  #1291 (permalink)  
 
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From some pages ago:
I just wonder why the diagram has them labelled in blue? I wonder why they would bother lifting them as the fadec is mounted on the engine.
The outer fan frame is a part of the engine, and yes, the fadecs are mounted on those sections.
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Old 13th May 2011, 14:28
  #1292 (permalink)  
 
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Pinger detection range

JD-EE:

I don't see where you accounted for either the spreading loss of the signal or the noise summed over the whole detection filter band (at least 100Hz). Remember that the noise figures I quoted are 1/sqrt(Hz). I refer you back to my original post on this topic (in fact, my first post on this forum):

http://www.pprune.org/5683946-post951.html

Given that Urick lists the noise at 37kHz, deep, as being between 18 and 42db re 1uPa/sqrt(Hz) for sea-states 0-6, I may have picked a little too much noise for my example, at 37db, but no less than 33db would be the right number. I don't think the 18db conditions are common; even sea-state 1 brings the noise to 25db.

Note also, in the case of the submarine (assuming, as I do, that it did not tow a deep array), that it is in shallower water, where its local noise may be a somewhat higher. Urick, first ed., shows little change in amplitude unless within a few hundred meters of the surface, but the only data are for 3kHz and below, so I don't know about 37kHz.
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Old 13th May 2011, 15:07
  #1293 (permalink)  
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JD-EE

Poser for you. The BEA description of the a/c's aspect at impact also describes a common aeronautical manouver. Do you know which one?? In deference to those who have not ruled out controlled flight, It is an attitude that allows an a/c to dump altitude rapidly and very safely. Perhaps if the pilots had reached desperation, and the weather could not be escaped either up and over, or around, they chose to descend below the monster ?? Without an altitude or airspeed to rely on, they may have gambled that they were higher than they were, and were still in aerodynamic flight, and ran out of airspace in the darkness and madness of the moment ??

This is consistent (strictly so) with BEA's theory. Left wing low, Nose right, rapid altitude loss.

Give it a go ??
 
Old 13th May 2011, 15:14
  #1294 (permalink)  

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This is consistent (strictly so) with BEA's theory. Left wing low, Nose right, rapid altitude loss.
It's not : Too much sideways velocity, deceleration of which doesn't match the BEA theory of fin detachment..
Another go ?
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Old 13th May 2011, 15:19
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Crabbing her in an extreme side slip?
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Old 13th May 2011, 15:21
  #1296 (permalink)  
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van Horck

Not a crab

Lemurian

Captain, this is for non pilots, no cheating. It actually helps the BEA's theory, as it gives the VS a more forward view at impact, solidifying the "pulled out" postulate. It also gives the fuselage a chance to rupture longitudinally, giving up the less damaged "components" to deposit past the Debris field.

Last edited by bearfoil; 13th May 2011 at 15:36.
 
Old 13th May 2011, 15:45
  #1297 (permalink)  
 
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Lemurian On another thread, someone posited that two items, one sinking to the bottom in 15 minutes, the other taking 30 mins, in a ONE KNOT CURRENT, they will be separated by 1500 ft at their resting places.
also in range are sinking times between ca. 10 an 60 min (600s-3600s) for falling a vertical distanc of 4000m in water, and a deap water currend with only 0,20 m/s (0.4 kn)......

the deapwater currend with this low speed then flow very laminar! and even the heavy debris need his time to reach this deapness.... as we tried to calculatet here before 4 weeks
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Old 13th May 2011, 15:46
  #1298 (permalink)  
 
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Bearfoil, it is a maneuver one might do in a no flap aircraft, and it is not an element of ladies apparel (hint). At the same time, the maneuver is not one used in jet aircraft for any practical purpose except perhaps a U-2. Good game.
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Old 13th May 2011, 16:07
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Looking at the debris field it seems to me possibly the aircraft impacted the ocean inverted....?
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Old 13th May 2011, 16:13
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gentlemen, if you go back a year yesterday to afriqiyah airways in tripoli the debris field was a pretty well jumbled up mess on hard sand iirc so its possible that this a/c could have been as that one for a second or two on the surface so that would explain the extra jumbled up mess on the seabed.
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