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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 3rd Mar 2009, 05:33
  #921 (permalink)  
 
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Kinetic energy

mickrussom:

F=ma
It's more like kinetic energy; Ek = 1/2 * m * v * v

80 knots ~ 41 m/s. Engine mass: 2400 kg. Ek ~ 2 Megajoule

Of course, not all that energy can be translated to forward momentum. After all it takes some work to detach the engine.
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Old 3rd Mar 2009, 06:12
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Originally Posted by bobcat4
It's more like kinetic energy; Ek = 1/2 * m * v * v
80 knots ~ 41 m/s. Engine mass: 2400 kg. Ek ~ 2 Megajoule
Of course, not all that energy can be translated to forward momentum. After all it takes some work to detach the engine.
I'm aware.

F=ma aka F = d(mv)/dt .
( http://www.math.colostate.edu/~reinholz/ed/07fa_m155/lectures/second_derivative.pdf )

In the interest of simplicity, to me its a simple momentum problem, and yes, some energy is consumed (what I referred to as shearing) to get them off the pylons.

Having seen lots of videos involving wrecks, high speed films of various explosions and the like, it comes down to things like this are more easily explained than predicted. Cream in coffee disperses via Brownian motion ( Brownian motion - Wikipedia, the free encyclopedia ), which is the easiest thing to observe but impossible to predict.

The point was is that very basic physics can account for why the engines tumbled further from the rest of the A/C. I do not think the engines were running in a detached state or any power developing from the detached engine will explain the position, they lie where they are mostly due to momentum after break-up.
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Old 3rd Mar 2009, 09:32
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I respect virtual flight deck forums of pprune as a passenger.
I am only interested in crashes which would also affect me (turkish), and try not to post unnecessary comments, unless there is a definitely positive contribution.

There is an article in Hurriyet, stating that CVR and FDR are encoded in Paris and a preliminary report is submitted to Netherland officials. Experts suggest there may be more than one factor.
Ve karakutu çözüldü... - Hürriyet

There will be press conference tomorrow. Please wait until the press conference before posting a theory.
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Old 3rd Mar 2009, 09:33
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Rainboe,

And what is the importance of where the engines are lying? It might surprise some of you, but crashing planes don't always behave 'logically'.
On the contrary, I strongly believe planes DO behave logically, although it's sometimes quite hard to reconstruct the nature of all the dependencies; that's why accident investigation takes a while (and sometimes leaves us with unanswered questions).
And debris distribution / condition of the wreckage could tell much about the circumstances, thus it's very thoroughly documented by the investigators.

what caused a perfectly fit 737 to fall out of the sky?
That's exactly what bothers us all. What we can see on the photos and Dutch police chopper video is consistent with relatively low forward speed with wings level, nose-high attitude and suggests significant RPM on at least one engine. Hopefully anaysis of FDR and CVR recordings will provide strong evidence (modern A/C = lots of data) and lead to causes of this situation. But now we're limited to some publicly available clues (of which photos are the most important and eyewitness reports - least). Of course we are waiting for the final report, though somewhat impatiently - hence this forum...

Regards,
MikeEPBC

Last edited by mikeepbc; 3rd Mar 2009 at 09:47. Reason: minor clarification
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Old 3rd Mar 2009, 09:56
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I think the biggest clue as to whether the engines were producing thrust or not is not where they ended up but how much damage the fan sections of both engines sustained.

Certainly the picture of the No.1 engine with very little if at all damage to the fan section would suggest this engine was in a failed state on impact.

http://cdn-www.airliners.net/aviatio.../2/1489234.jpg

PJ2

Last edited by puddle-jumper2; 3rd Mar 2009 at 10:07.
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Old 3rd Mar 2009, 10:32
  #926 (permalink)  

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Exclamation Don't use movie special FX to found any suppositions on here!

Now that we've had a bit of time to breathe, I'd like you all to know that there are far too many uneducated and irrelevant posts being made on this thread. So far, there have been 1,532 posts of which 595 have been deleted.

As a plea on behalf of the mods who have to read through some of the most pathetic, idiotic and argumentative posts and then trawl back through the detrius and delete them, please limit your comments to relevant areas of this crash. Watching some of you try and explain why you believe the engines were or weren't developing thrust after they had separated from the wing is just cringingly painful.

The only evidence I can extract from this thread, so far, is that far too many of you didn't pay attention during physics lessons in school and have general knowledge of physics based on special effects in movies. In other words, too stupid to post here.

If you don't want to wast your own time and effort then think carefully before posting because you may be wasting ours and everyone elses too.
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Old 3rd Mar 2009, 11:12
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puddle-jumper2
Certainly the picture of the No.1 engine with very little if at all damage to the fan section would suggest this engine was in a failed state on impact
I might normally agree with your statement, but not necessarily here

Damage to the Fan section as an indicator of power also relies on knowing how quickly that Fan was brought to a "halt". Those engines look pretty intact in terms of distortion to the Fan Case... if the Fan is free to rotate to any degree during the impact sequence i.e. not brought to an instant stop, bang goes the theory

NoD

Last edited by NigelOnDraft; 3rd Mar 2009 at 16:29.
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Old 3rd Mar 2009, 11:19
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lektem

You posted this info on two of the crew. Do you have the same type of data for the third pilot? Thanks.

"Captain Hasan Tahsin Arısan was one of the airline's most experienced senior pilots who had more than 15,500 hours of flying experience. Captain Arısan had been working for Turkish Airlines since 1996. He was also a former Turkish Air Force fleet commander, who had over 5,000 hours of flight time on the F-4E"
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Old 3rd Mar 2009, 12:18
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Dysag

I don't know which pilot you are asking. Let me give information about all of them :
‘Uçtuğunuz uçağı çocuğunuz gibi sevin, tanıyın ki o da sizi dinlesin’ / Türkiye / Radikal İnternet
Hasan Tahsin Arisan :
55 years old. Graduated from military academy in 1976. Resigned from turkish airforces and joined THY in 1996. Known as a good instructor and being calm in emergency situations.
Olgay Ozgur :
29 years old. Graduated from university in 2005. Started in World Focus Airlines. Transferred to THY in 2007. Had about 3000 flight hours.
Murat Sezer :
42 years old. Resigned from turkish airforces and joined THY two years ago. Had about 3800 flight hours.
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Old 3rd Mar 2009, 12:44
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Nigel,

I can't remember ever seeing a high bypass jet engine, after hitting the ground with such force as to rip it off it's pylon and throw it down a field, with the fan spinning at moderate/high power on impact, that didn't sustain a high amount of fan blade damage

Can you ?



Here's what I would have expected it to look like if it was producing power..... i.e. the No.2 engine.

PJ2
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Old 3rd Mar 2009, 13:13
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puddle-jumper2

Re "I can't remember ever seeing a high bypass jet engine, after hitting the ground with such force as to rip it off it's pylon..."

As has been discussed on other threads, Boeing engines are attached with "fuse pins" designed to allow them to separate in a case like this.

It's to meet an FAA requirement that "large masses" should not cause further damage to what remains of the plane. Especially the pax cabin.
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Old 3rd Mar 2009, 13:23
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Dysag

It's to meet an FAA requirement that "large masses" should not cause further damage to what remains of the plane. Especially the pax cabin.
Please don't make things up. It confuses the trolling reader
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Old 3rd Mar 2009, 13:30
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lomapaseo

What do you mean? I may not have quoted the FAA verbatim, but sometimes I know what I'm talking about.

BTW, on the A300 et al, Airbus adopted a different means of compliance: that the engines should stay firmly attached.

Para 1.6.3.1 of the Dutch investigation into the El Al 747 accident.

http://www.verkeerenwaterstaat.nl/ke...light_1862.pdf

and:

BW Online | July 5, 1993 | BOEING: FOR WANT OF A PIN...

and:

FAR Part 25.561 General.

...(c) For equipment, cargo in the passenger compartments and any other large masses, the following apply:
(1) Except as provided in paragraph (c)(2) of this section, these items must be positioned so that if they break loose they will be unlikely to:
(i) Cause direct injury to occupants;
(ii) Penetrate fuel tanks or lines or cause fire or explosion hazard by damage to adjacent systems; or......

Last edited by Dysag; 3rd Mar 2009 at 14:32.
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Old 3rd Mar 2009, 13:37
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.....................?

Last edited by Rainboe; 17th May 2009 at 17:48.
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Old 3rd Mar 2009, 13:50
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Dysag & Lomapaseo,

In an effort to clarify . . .

Secondary structures (such as seats, galley, etc.) are required to be designed and tested for security for specific load factors to protect the passenger cabin including the cockpit.

The engine mounts are designed to separate without rupturing the wing tanks which indirectly protects the cabin from fire damage.
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Old 3rd Mar 2009, 14:08
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Dysag,

Your missing the point.

I'm not questioning the fact that the engines detached, or that they are designed to detach.

I'm questioning the deference in fan section damage between the 2 engines.....both of which detached with more or less the same force.

They also ended up slightly left of centerline - another clue perhaps.
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Old 3rd Mar 2009, 14:22
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Is it important? It all depends on yaw at touchdown, drift, touching down on one side first. All variables thrown into the mix changing final position and alignment of the engines, not that it matters anyway!
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Old 3rd Mar 2009, 14:31
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Sigh! Whether it hit the ground flat, nose high or like a dart in a flamin' dartboard, it's after the event that caused the ground impact. Whether the engines are 100 m in front of the aeroplane or 100 m behind it (I seem to recall a 757 going off the runway in Spain somewhere, where the engines went up and over the wing), it's after the event, a result of the impact, not the cause. All these physics formulae being bandied around about where the engines ended up tell us nothing about the event that initiated the chain to impact with the ground, they could have been flipped forward like tiddlywinks for all I care. In fact, given their position on the wing and a low forward airspeed and a high vertical component, they might well have been

I wanna know WHY it hit the ground, not HOW it hit the ground. All the important bits in this accident, except maybe survivability issues, are pre-impact, not post impact.
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Old 3rd Mar 2009, 14:36
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I wanna know WHY it hit the ground, not HOW it hit the ground. All the important bits in this accident, except maybe survivability issues, are pre-impact, not post impact.
I've been trying to say this since the crash. The leagues of sudden instant 'expert' accident investigators (untrained and unqualified!) seem to want to focus on the deaths and injuries and impact only, not what happened in the air. Why? Nearly 1000 postings, and we have narrowed engine condition at impact to somewhere between the narrow band limits of Full G/A thrust down to not rotating at all! Therefore not to be persued any further until official data released!
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Old 3rd Mar 2009, 14:37
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A bit more clear now....... I mean the picture !!

Last edited by Giolla; 3rd Mar 2009 at 15:00. Reason: The PICTURE is more clear
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