Air France Jet Missing Off Brazil Coast

[rpm]

Vertical stabs just aren't designed to do that.

Well if you design them out of 2 foot thick steel they would. It would never leave the ground tho.

[MrRiplEy[H]]

I think Humble just put a foot in his mouth and is now trying to gag it out.

AFAIK composites are used for the exact reason that they're stronger and more flexible than steel counterparts especially when compared to weight. The fishing rod was an excellent example - how many steel fishing rods have you seen? It flexes and carries several pounds of load despite being tenth of an inch thick in the head. A metal would deform and snap broken after a couple movements.

Ceramic components can be brittle yes, but only if they're designed to be primarily hard. Ceramic carpet laminated on eachothers is not brittle especially when combined to kevlar / carbon fibre. It's basically as far from brittle as current tech can make.

The only way a modern aeroplane composite can be brittle is if an error was made during the laminating process and the lamination itself will break.

[mtnman]

The fishing rod was an excellent example - how many steel fishing rods have you seen?

 A metal would deform and snap broken after a couple movements.

Hmm, there's one down at my grandmothers house, unless she got rid of it.  It was one of my grandfathers old rods.  A bit heavy, but otherwise quite functional.

Metal doesn't have to deform and break after "a couple movements".  Depends on its formulation and temper.  An example of a hard, fairly brittle metal that can handle lots of movement without deforming and breaking is a spring.

[moot]

Ripley, what's the failure mode of those ceramic/kevlar/carbon carpets like, compared to metals?

[straffo]

Ripley, what's the failure mode of those ceramic/kevlar/carbon carpets like, compared to metals?

Under what condition (temp,pressure...) and compared to what kind of metal ?

[moot]

That's what I was thinking too. Just asking to see if there's any characteristic trend, or if it's a crapshoot from all the variables.

[straffo]

crapshoot of variables look to be a good definition !

I'm pretty incompetent in RDM (Résistance des Matériaux/Strength of materials) as it was far from my preferred course I just remember some huge headache
The only thing I can say is : it's can be as simple as saying metal vs composite.

[Angus]

They can, but not for long and not without incurring damage, and eventual failure. What you feel during take-off and landing is at most 1.5G. 2.5G is actually a lot more than most virtual "pilots" think.

I know. Jostle around in them little ones every now and then.
I hate - G's, yeachh!

[MrRiplEy[H]]

Hmm, there's one down at my grandmothers house, unless she got rid of it.  It was one of my grandfathers old rods.  A bit heavy, but otherwise quite functional.

Metal doesn't have to deform and break after "a couple movements".  Depends on its formulation and temper.  An example of a hard, fairly brittle metal that can handle lots of movement without deforming and breaking is a spring.

True but when weight is taken into account I think the scale tips over to composites. If I recall right they said the A380 could not have been built without extensive use of composites due to weight limitations. The brittle nature / stress factures issue is not when speaking about metals in general but when speaking about aircraft grade aluminium compared to composites.

The biggest problem (I think) at the moment is that the laminating process is very demanding as it requires a certain temperature to be successful. If the temperature is wrong (too low) the laminate doesn't adhere and becomes brittle.

[Fishu]

Isn't there a single discussion with americans anywhere on the matter of the missing plane without airbus vs. boeing hoopla!? Come on, you all have been discussing this like hundred times over in the past years and it only ceased for a while when the 787 experienced a delay, after there had been so much whining about the tiniest problem with the A380. There's no such thing as a perfect plane nor a perfect company and you can debate about that all day but it's not going to change. Neither company would be in the business if their record would be piss poor.

Now, about the missing plane... I've read from the news that supposedly some passengers were able to send short text messages with their cellphones to their relatives. Nothing was heard from the pilots, but there was still time to send text messages?

[Nilsen]

I belive the passengers were worried about the bad weather and sent txt messages before whatever final event that made the plane crash. The text messages are several minutes apart and prolly not sent while the plane was going down.

Also im THINKING that maybe the pilots may have been busy trying to fly the plane
Their voice comms prolly does not use the same system for transmitting as cellphone communication on the plane either. Maybe the system the pilots used was out but not the cellphone system.

Many reasons why txt's got through and not the pilots vox.

[FTJR]

Very sceptical about the text messaging scenairo, most airlines haven't approved the use of mobile phones in flight, and if they did send text's they'd have to be in range of land.  When you go out of Radar range in that area you are effectively out of VHF range, so you have to rely on the HF, which is always somewhat "iffy". So It is reasonable to assume they were in the "aviating part" of the flight, and couldn't/didn't have the time to try to communicate.

[Nilsen]

Cellphones over sat. not that uncommon but dont know about air france

[FTJR]

Are you refering to the common cell phones everyone carries around with them, or those phones in the seat backs, for 10 USD a minute? I stand to be corrected but I really dont think it will hold up. Anything is possible.

[Nilsen]

A quick google revealed that air france allowed mobiles on their planes back in 08. Their system is sattellite based and allowes for text and voice comms but not data. Since then i bet alot of airlines have implemented them.