News and theories about the missing Malaysian plane

Mh-370

Good idea about the beacon. The 'black box' was placed in the tail because it had a history of survival when the cockpit was destroyed.

i think this might be the first time a modern commercial airplane has flown in to water under full autopilot. Most crashes so far, the plane has 'augured in' (technical term) and your comments are true. This time the complete lack of floating debris might mean the plane 'landed' more or less complete, and might still be complete on the bottom somewhere.

I would still like an opinion on how far such a 'light' high volume wreck might 'drift' between leaving the surface, and 'grounding' several miles down. My statements about 'hovering' were based on ignorance, and an overappreciation of the density of thermoclines.

I appreciate your comments Mr Efficiency, but i am talking about the significant dwell time between the airplane departing the surface, and finally having enough 'weight' to actually stick to the bottom. If steel ships drift a long way under these circumstances, how much more a aluminum shell barely heavier than water. Remember the empty fuel tanks are basically sealed, and the pressure cabin fairly well sealed (they leak outward all the time, the 'pump' just keeps filling them up).

There is a lot of 'stuff' in a plane that floats forever, seat cushions etc. I can only assume all seat cushens are held in place by the bodies still strapped to them, but this too is slightly improbably, NO empty seats? or no burst pressure vessel.

 

Okay, if you guys aren't going to quit speculating then we may as well have at 'er.
Once the bodies start to gas up inside, they'll start repressurising the cabin of the "glider" enough to make it neutrally buoyant and it will been seen intermittently all over the global ocean over the coming years.

 

Awesome theory Navy! Here's mine: it was actually a charter flight (the Malaysians forgot they leased it out) and when the passengers have finished their tour of someplace without TV they'll all come home again

Sailor: I'm not sure we know it was on auto, but if it did a wet landing with empty tanks it would have floated for hours and drifted with wind and current until the fuel tanks collapsed. Even US1549 with full tanks floated for long enough - after Captain Sullenberger's awesome landing on the Hudson River - for everyone to get out and for the plane to be towed to shore.

With passengers and crew dead through lack of oxygen the doors would have stayed sealed, and it is likely that one or both engines would have detached; I've no idea how long a plane in that condition would float, but not days because the cabin rear vent would remain open as it has to be shut manually for a wet landing.

Either way the wreckage could be a long way from where the search is being conducted, but only miles not hundreds of miles, so it should be found within a few months if the search is conducted outwards from the current search area.

 

Once that plane started to sink all those sealed spaces are going to be crushed by pressure. They won't stay sealed for long, they'll implode and the sectional density will therefore increase. No way any aircraft is going to be built to withstand even 10 Bar of external pressure.

One old trick of ours was to send a polystyrene coffee cup down to the bottom in 5000m of water. What you got back was a thimble. OK that's an exaggeration but it was a lot, lot smaller.

PDW

 

Little green men came and scooped it up in mid flight. I met a guy in a bar who saw everything.

You heard it on Boat Design first.

 

Malaysa 370

Thank you PDWiley, it shows how little i consider our structure under external pressure.

In fact the wing fuel tanks only take 100-200lb internal pressure before they fail at a known point, usually on the rear spar, and before you ask, i do not remember where this failure was, nor the pressure on a 777. We used to make this pressure much lower, but discovered some operators were disabling the pressure relief on their ground fuel pumps so they could fill the planes faster. Fuel pumping time has always been a tent pole in turnaround time. Note; the front spar is sized for fuel load sloshing forward in a crash, and therefor rather stronger.

Note, this point is ‘internal’ pressure, but somewhere nearby it should fail from external pressure. Once this is breached, you are right, PDWiley, the wing tanks would flood pretty quickly. The wing tips, outer wing panels really, contain a complicated fuel pressure relief system, designed to contain fuel as the plane banks, but equalize internal pressure otherwise. There are also fuel vent tubes for exiting air whilst refueling. Really new planes have much of this replaced by the nitrogen interting system, intended to replace the completely inert fuel vapor, with completely inert fuel vapor and nitrogen. Don't get me started on unnecessary changes for public perception.

The body is another animal. It has very little external pressure capability, and i didn't know about the pressure relief valve. It is a good design, and certified, so i am sure we used it for decades, and used it again on the 777. There are plenty of small holes, leaks, in the pressure body, through which air could escape, but not so many in the crown. most of these would be sealed permanently, against rain if nothing else. These small holes whistle badly, and annoy the PAX and crew, so they are usually found and sealed on the first or second test flight.

Given all this, i guess the plane might have 'floated' for several hours before flooding and sinking.

I discused earleir how the engines might have departed, and might not.

 

Well, maybe not, but with not a skerrick of wreckage found anywhere, you really wonder what happened.

 

Well you mention that..... did anyone see yesterday that the media reported (Daily Telegraph in the UK) wreckage (metal pieces) having been washed ashore in Oz and the authorities saying they were sufficiently interesting to warrant further investigation? Then 90 minutes later the story had been pulled and nothing since? No joke, that's what occurred.

 

Later reports about that material washed up said it had been examined and declared to be not connected to any aircraft. They did not say what is was, though.

 

Makes you wonder what that 24 metre piece of flotsam was they first discovered in the southern ocean doesn't it?

 

Mh-370

I heard that the metal found on the Australian coast was aluminum with rivets in it. As a very large number of simple Australian boats are made from sheet aluminum, fastened with dome headed rivets, there could be a bit of excitement generated by such a find. Fortunately one glance by someone in the marine industry, let alone someone in the aerospace industry, would identify it for what it was. I suspect embarrassment might have caused the withdrawal of the article.

If you needed analysis, the aluminum would have been marine grade, probably 5xxx or similar, or possibly 6xxx. Aircraft use exclusively 2xxx, and 7xxx grades, and these should never be used for a marine environment. Though i do notice these grades, especially 2024, appearing on marine sites.

Whilst the aft fuselage of some big commercial airplanes use dome head rivets, the boundary layer is so thick there, we need not have a flush skin, it is isolated to this area. All the rest of the plane is “Flush” riveted, and the rivets are usually quite small if the sheet aluminum thin. How a piece of aluminum ‘floated’ to this point and was washed up, i cannot imagine, but it might have had foam floatation, or insulation, bonded to it.

 

Maybe it sank before it could be located, but if not.......why has it not been tracked down. What odds a large piece like that could remain afloat for weeks, then sink. Seems atypical.

 

Sigh. It was spotted (well, something was) from a satellite. There's no guarantee that thing was actually *on* the surface, there's no way to tell unless you've got a really, really good radar. Could have been just sub-surface, could have been a big sheet of plastic, who knows....

Even if it *was* on the surface, spotting something at surface level from the bridge of a ship is quite difficult.

I do wish some of you conspiracy theorist types would actually get your arses aboard a vessel of some sort, go out into deep water and try to find something that someone has told you is in a certain place. You might actually learn something about how hard it actually is.

PDW

 

Who specified " the bridge of a ship" ? There was a swarm of high-tech military aircraft criss-crossing the water, and unlike the subs they are designed to track, this thing was not trying to hide, or moving independently of the elements.. And they had the benefit of satellite location, and the knowledge of currents, etc etc. It could have been a modern day Moby Dick I suppose, white, 20-odds metres long, bad temper.

 

Not a joke, just a lead that led nowhere, it was found, checked out and dismissed as not part of a plane. It is mentioned all over the internet, certainly no secret, also mentioned on Canadian TV for a couple of nights.

I didn't see a report identifying the material although aluminum seems most likely - presumbly with some buoyancy . . .