AF 447 Search to resume (part2)

[Machaca]

Le Monde reporting not all bodies will be recovered.

[mm43]

Originally Posted by RR_NDB ...
Pingers are VERY simple devices. And not costly.

It´s "performance" can be (easily) improved.

Why not (for longer range airliners) use extra pinger(s) with specs. like:

• Better (mech.) survivability (not a tiny one attached to a CSMU)
• Increased duty cycle (allowing RX DSP)
• Better frequency spec. (<1%)
• At another (lower) frequency
• Battery capacity (also) up to 90 days

The BEA commissioned a Flight Data Working Group to undertake a technical analysis into -

• Flight Data Transmission
• New flight recorder technology
• Wreckage localisation technology

The FDWG Final Report is in PDF format and is well worth a read.

[thermalsniffer]

Position Report

Wes_Wall

In addition to the 2:10 operational message, there was also the inspection of the RTLU discussed in the second report at pp. 26 (English version), offering some additional data.

[jcjeant]

Hi,

Confirmation about the bodies ....

The French court on Tuesday warned families of the victims of the crash of Paris-Rio that the bodies of their relatives who would be too corrupted and impossible to identify will never be recovered, when the black boxes of the Air France Airbus are expected on Thursday at Le Bourget.

Source
midinews.com: : Rio-Paris: les corps trop abms pas remonts, les botes noires jeudi Paris

[Turbine D]

Machinbird

Well lets get started. Let's examine these facts.
My favorable experience with jet engines at high AOA does not include experience with Fan type wing mounted engines. Why are Fan type engines so much more finicky (if they indeed are)? And as always, others are welcome to join in.

Since the J79 engine (an augmented turbojet), nearly all the newer military fighter engines are actually augmented turbofan engines. A major difference, of course, is the diameter of the fan. The core of the CFM56 engine is basically the same as the core of the F101/F110 engines. There are some key differences that are addressed in different manners. On military fighter engines, the flight envelope is more extensive than a commercial turbofan flight envelope and therefore must handle more severe conditions, more or less whatever the pilot wants the fighter to do. Engine controls have advanced providing more operating stability across the flight envelope. For both commercial and fighter engines, the control systems are designed to regulate engine power and efficiency by manipulating available variables as a function of sensed parameters. The manipulated variables are varied to schedule or set the controlled variables. The controlled variables and sensed parameters are selected to meet system requirements.

All turbofan engines have unique component requirements to maximize efficiency and ensure stall free operation. For example, fighter engines require a fan IGV (inlet guide vane) that can be varied for inlet distortion control. In the CF6-80E engine, the high pressure compressor inlet is "supercharged" by the low pressure compressor that consists of the hub section of the big fan and 5 airfoil stages.To provide adequate stall margin, a VBV (variable bleed valve) system is incorporated into the fan frame, which are actually hinged doors. The doors are open at idle to discharge air into the fan flowpath (bypass), but at high power the doors are closed to improve engine performance.

So, controlled variables include fan speed (N1), core speed (N2), HPT blade temperature (T4B) on fighter engines, exhaust gas temperature (EGT), compressor discharge pressure (PS3), augmenter fuel flow (WFR) on fighter engines, fan discharge Mach number (M25, ∆ P/P) on fighter engines, and fan and compressor variable geometry (IGV's, VSV's and VBV's).

The manipulated variables which are modulated directly by the control system to maintain control of the above controlled variables are as follows:

1. Main fuel flow (WFM)
2. Augmenter fuel flow (WFR)
3. Exhaust nozzle area (A8)
4. Compressor variable stator vanes (VSV's)
5. Fan variable inlet guide vanes (IGV's)
6. Variable bleed valves (VBV's)
7. Thrust reverser

This is only a short listing where stall prevention is prime, but demonstrates quite a few similarities and some differences in today's modern turbofan engines, commercial or military.

In my opinion, big turbofan engines today are no more or no less "finicky" than their modern day fighter engine counterparts. I should add one other comment: Most of this technology evolved from the military J79 engine, the difference being the J79 produced 17,000 pounds of thrust and the F110-129 produces 30,000 pounds of thrust!

TD

[glad rag]

Quote:
The French court on Tuesday warned families of the victims of the crash of Paris-Rio that the bodies of their relatives who would be too corrupted and impossible to identify will never be recovered, when the black boxes of the Air France Airbus are expected on Thursday at Le Bourget.

Re my earlier #833
"There may be a "practical" reason for recovering a seat still strapped to a corpse."

Let us remind ourselves of what has occurred over the last two days; and also remind ourselves of the sea pressure at the bottom on the abysmal plain.

[RR_NDB]

BEA´s Flight Data Recovery Working Group

Hi,

The BEA report provided by mm43: Link

The solutions that stem from this evaluation are
ˇ Extended duration of emission of the ULB attached to the flight recorders (90 days
instead of 30 days),
ˇ Installation of low frequency ULB (between 8.5 and 9.5 kHz) attached to the plane,
ˇ Regular transmission of basic aircraft parameters (via ACARS for example),
ˇ Triggered transmission of flight data. On this point, additional work is deemed
necessary and the BEA will again consult members of the group to conduct a study.
And,
ˇ Installation of deployable recorders.

And the 2nd Solution at page 10:

[bearfoil]

gums

Hiya. The reason I believe that the impact zone "heading" has no relationship with the debris Field's "direction", is as follows. Very vertical, very energetic impact. The debris was "focal" (compact) and the debris distribution on the seabed reinforces that the heavy things sank very nearly in the same trajectory. Whichever direction the impact was, the engines were destined to be the "beginning" of the seabed "trail" and the heading away from the engines at impact on the seafloor will reflect the subsurface current only. To suggest that any current in the sea was the same as the final nose direction is betting 360-1.

The reciprocal of the debris' "direction" is no less likely than the "perceived" WSW, so let's make the odds 180-1. The lighter things would sink a bit slower than the engines, so would reflect only the current, not the initial impact's orientation.

Get my....Drift?? We don't really know her heading much after 0210, how can we predict what it was on the surface at impact? Especially since there was LOC, and the BEA themselves have said the airframe was yawing right when she hit. A water impact is not at all like a surface debris trail, she didn't stop crashing until she hit the bottom. The "engines forward" trail tells us nothing of her orientation at impact. IMHO.

yo

hmmm...How about, since you admit she changed course, was it intentional? Unintentional?? With LOC, impact heading is de rigeur random, and since there was LOC, intentional heading is impossible.

[BarbiesBoyfriend]

Come on Bear. If it had 'gone in' like a tent peg, would they have found the galley intact?

[Machinbird]

Hi Bear,
So in your opinion, the relative positions of one engine to the other engine on the sea floor is just random?

[bearfoil]

Ken

I don't speak tent peg, I grok vertical, negligible horizontal. (A searcher spoke about the a/c having "virtually no horizontal at impact"). I have NOT injected anything here that is not consistent with the data so far. The Galley can have survived according to BJ-ENG. That is good enough for this cowboy.

yes?
bear

[bearfoil]

Machinbird

We don't know how the engines are indexed on the seabed, Seabed #1 could be A/C #2, or vice versa. If the orientation is bilateral, #1 seabed and #1 is port, (same-o) then I would predict the engines have a relationship to water entry, but again, that has to include both WSW +/- ~15 degrees, and ENE, +/- ~15 degrees. That the flight to the bottom was 2.3 (miles), the demand is for nil current if one wants to conclude the line of debris is the line of the a/c's last moment in the air. The engines could have swapped, anything could be at work. I think it is a stretch to conclude the debris is the telltale of "Line". Besides, there is no way to conclude that any line above or below the surface has anything to do with controlled flight, and since the orientation is random by definition, how can one extrapolate a "finding" re: heading?? It can have nothing whatever to do with anything.

Phabulous Phantoms Phorever

bear

Captain Scott. OK. The line was either WSW or ENE, and since the a/c was completely ooc, that tells us exactly what?? That the pilots would abandon recovery to rollout on some "heading"??????

This a/c absolutely, abso-Freaking-lutely had a heading of 240 when she hit. What did the Captain have for Breakfast??

[Chris Scott]

Machinbird,

Did someone ever come up with a theory as to which engine was which in the debris field? Is it as-per takata's interpretation of the BEA image? Can I assume that you also think the engines would have gone pretty-well straight to the bottom, having separated in the first second of this low-speed impact, therefore giving some indication of aircraft heading at sea-level impact?

[3holelover]

Did someone ever come up with a theory as to which engine was which in the debris field?

The BEA will know by now. They've got serial numbers from the one they pulled up.

[Dave Senior]

FlamantRose, mm43:

My suggestion is that there is a comma missing after requin (otherwise it doesn't mean anything in french). Obviously this "requin" cannot be strange or odd ! It's the facts that are strange. It would then read "ballonné et endommagé par la morsure de requin, étrange !" and could be translated by :

"swollen and injured by a shark's bite, strange (peculiar)".

Does this look any better ?

Nope, not really! I think you are overlooking the most obvious translation of the word Etrange which is "unknown".

The sentence would then translate as "Bloated and damaged by the bite of an unknown shark".

/dave (bilingual Canuck)

[Chris Scott]

3holelover,

Yes, the BEA certainly do know. Frustrating, isn't it?

Chris

[Shadoko]

Hi,

Perhaps one more stupid question: with ~50 supposed unbuckled recovered at sea, there was perhaps 100 of them like that in the plane. With a sudden pitch, that makes about 6 tons moving backward (nose up) or forward (nose down) in the plane. Doesn't make a big unbalance? And more: if falling forward, perhaps some fell into the cockpit? Would be pretty messy.

May the deformations observed by BEA on interior equipments be the result of people or carts falling on them?

I am very surprised by the different "states" of different "things":
- Engines seems fully destroyed (Hudson ditch: haven't seen the one torn out, but the other seems in relatively good condition and they stopped the plane which was going ~130 knots), mobile surfaces seems all gone, front part of the left wing seems torn (if it is left one).
- And other parts seems in very good condition (the "galley" floating, electronic bay equipments).
How to explain that?

One more: is it possible the compression "from below" of the BEA report on structure parts was the result of water pressure after an almost vertical dive, nose first? (radome smashed, no very big deceleration before the wings touch the water, big decelaration then, with VS pushed forward, wings and engine torn. The aircraft body (or only broken forward part) keep diving, all rear surfaces torn when touch water. If the body keep diving it will be crushed by pressure very soon (and due to the foor, it is crushed from top and below). The speed is now very low and some parts could float up to the surface, but nothing from the cockpit, as this part is going straight to the bottom.)

Final question (and sorry if shocking): would be the "no recovering" corpses due to too many missing (not retrieved at sea two years ago, and not in the wreck)?

Sorry if this all a stupid story, it is perhaps too late to write...

[auv-ee]

Bloomberg: Recorder analysis

Air France Crash Analysis Reaches Lab as Black Boxes Return Home - Bloomberg

There is some interesting info on the possible process of analyzing the recorder data. I expect those more familiar with the process may have comments.

[bearfoil]

Shadoko

Seems quite reasonable to me. But not the Nose dive part. If the galley and other parts were aboard in a nose first impact, they would be smithereens. It is conceivable the lightly damaged parts exited with little damage in some fashion that includes a fortuitous slowing and quickly opening forward fuselage. The only other possibility, that these parts left the a/c earlier, perhaps with some passengers, is forbidden to discuss.

Evidence points to a rather flat impact, belly down. Wings close to level, and the airframe rotating slowly to starboard. Works for me.

cheers,
bear

[Machinbird]

Chris Scott

Can I assume that you also think the engines would have gone pretty-well straight to the bottom, having separated in the first second of this low-speed impact, therefore giving some indication of aircraft heading at sea-level impact?

Hi Chris, yes I do. The engines were likely separated from the aircraft within the first 1/100th of a second post impact. Water is such a dense medium that I would expect it to rapidly remove all residual velocity vectors resulting from the crash. The only velocity vector then remaining would be the velocity vector being generated by gravity as modified by any hydrodynamic forces that might result. Even with an engine generating hydrodynamic forces from its travel through water, it likely that the forces would not be completely symmetric and would thus create some rotational velocity along some axis as the engine falls to the ocean floor. This rotating force would create dispersion from the ideal. Of course the engines would move with the slow moving current, but their time of fall (due to their massive nature) would be short and total displacement minimal with both engines displaced almost identically (Assuming the final configuration of both engines was indeed comparable.)

The fact that the engines are about twice the distance apart on the ocean floor than they were on the aircraft might result from the total mass of the aircraft displacing and entraining a local segment of the ocean that absorbed its energy, and the mass of downward moving water and wreckage would fan out radially from the initial point of impact for a brief time until the impact energy was fully dissipated. This should displace wreckage away from higher velocity cores, but since this energy would be rapidly dissipated, the effect would be short lived but not entirely negligible.

For a mental picture, imagine dumping a bucket of dirty water into a clear lake. The initial interface between the two would look something like an inverted mushroom.