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Tail, Turbulence Emerge As Keys To Flight 587 Disaster
Aviation Week's Aviation Now ^ | 11/14/2001 | Sean Broderick

Posted on 11/16/2001 1:15:07 PM PST by Swordmaker

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"the engine signatures extend past the start of the loss-of-control event."

This means that the engine sounds continue normally AFTER the event that precipitated the crash began... in other words it was not a loss of an engine that knocked the tail off. But then we had already concluded that. The loss of the tail HAD to be the initiating event. The question then must be asked : did the engines fall off because of the same problem that caused the tail to fall off?

IMPORTANT! The plane actually took off earlier than reported and was only 1 minute 45 seconds behind the Japanese 747! Turbulence to a weakened tail may be the real answer!

1 posted on 11/16/2001 1:15:07 PM PST by Swordmaker
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To: Swordmaker
The plane actually took off earlier than reported and was only 1 minute 45 seconds behind the Japanese 747! Turbulence to a weakened tail may be the real answer!

You definately heard what they told you.

2 posted on 11/16/2001 1:15:08 PM PST by TheOtherOne
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To: Swordmaker
Based on what I learned when I was studying fluid mechanics in engineering school (O! so many years ago), we would have called "wake turbulence" by it's engineering name, "von Karmen vortex shedding". This is the phenomenon where a bluff body in a fluid flow causes a vortex (a "tornado") in the downstream flow. Go here and go to page 2, Figure 3, item (c) at the upper right, for a diagram. As the jet accelerates on takeoff, it passes through this higher-drag, unsteady flow regime on the way to a more smooth, steady flow regime at cruising speeds.

FYI, Theodore von Karmen was an early fluid dynamicist.

3 posted on 11/16/2001 1:15:08 PM PST by FreedomPoster
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A diagram of von Karmen vortex shedding from an airfoil:


4 posted on 11/16/2001 1:15:08 PM PST by FreedomPoster
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To: FreedomPoster
You left out this:

In this reverse von Karmen vortex street, water is accelerated backwards through the vortices. The magnitude of thrust is a function of the mass and acceleration of this backwards moving water.

5 posted on 11/16/2001 1:15:09 PM PST by TheOtherOne
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To: TheOtherOne
Anyone with any knowledge of fluid mechanics knows that fluid flow tends to be the similar for all fluids. Water, air, petroleum, whatever - it's all fluid flow. There's nothing magical about air that causes it to act substantially differently than water.
6 posted on 11/16/2001 1:15:09 PM PST by FreedomPoster
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To: FreedomPoster
or, as they say in the fluid dynamics biz after a drink or two -- when it comes to fluids, molecules is molecules
7 posted on 11/16/2001 1:15:11 PM PST by AntiScumbag
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To: AntiScumbag
EX-actly!
8 posted on 11/16/2001 1:15:11 PM PST by FreedomPoster
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To: Swordmaker
The only thing suffering from wake turbulence are the minds of those who buy this nonsense. It is a red herrrrrring. Wake turbulence affects the horizontal stabilizers [wings] not the vertical stabs [the tail]. The rattle that the pilots heard was the tail and probably engines shaking loose from their moorings. The tail section had six fastening points -- all failed simultaneously This is either mechanical negligence or sabotage.
9 posted on 11/16/2001 1:15:21 PM PST by Woodkirk
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To: FreedomPoster
But the NTSB guy said the planes got as close as 4.3 miles and an altitude separation of 800 feet.

So the pictures TV showed of a test where the two planes in the test, one behind the other, with the following plane yawing in the wake and turbulence should have had it's tail break off as well? It looked to be a lot less than 4 miles between them. Maybe 2,000 feet.

... And when a plane encounters a bad thunderstorm the tail just falls off?

... And the huricane hunters, why they keep a supply of extra tails back at the hanger to replace the ones which fall off when they fly through a hurricane.

... And in midair refueling better have that spare tail handy. Some toilet paper too. Mid-air tail replacement after refueling?

... sounds a little fishy, errr taily, to me.

Loose bolts anyone? Missing bolts> Cut brackets?

snooker

10 posted on 11/16/2001 1:15:22 PM PST by tarpon_bill
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To: Woodkirk
Wood....

Seems as if I read somewhere that the Japanese 747 flew for quite some time without the vertical stabilizer.

11 posted on 11/16/2001 1:15:23 PM PST by cynicom
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To: cynicom
They call it a stabilizer for good reason.

Ever see a bird without a tail fly. Tough to do.

snooker

12 posted on 11/16/2001 1:15:24 PM PST by tarpon_bill
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To: tarpon_bill
I think it's entirely possible there was something wrong with the tail, that caused disaster when combined with turbulence from the 747's wake.
13 posted on 11/16/2001 1:15:24 PM PST by FreedomPoster
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To: FreedomPoster
Agreed. Take out a few bolts, tail falls off in flight.

Maybe not, but you never know --- Hard to find bolts that were missing after the plane takes off and crashes. Turbulence might just have made it happen sooner, rather than later in the flight. High stress occurs at takeoff/climb out.

snooker

14 posted on 11/16/2001 1:15:24 PM PST by tarpon_bill
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To: tarpon_bill
Loose bolts anyone? Missing bolts> Cut brackets?

And then there are these to consider:

Crash not seen part of terrorist warning (US Received 11/12 Warning)
Air Authorities Monitored Terrorist Threats After Downing Of Flight 587

15 posted on 11/16/2001 1:15:25 PM PST by Lion's Cub
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To: **AA Flight 587
Indexing
16 posted on 11/16/2001 1:15:25 PM PST by Lion's Cub
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To: tarpon_bill
I heard somewhere, in passing, that they had the bolts. That would be quite the find! There have been several other threads on the topic of criminally mislabeled low-strength bolts with high-strength markings, as a possible cause of this crash.
17 posted on 11/16/2001 1:15:26 PM PST by FreedomPoster
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To: tarpon_bill
bill....

The Japanese 747 did in fact fly without the vertical stablizer for quite some time until they ran into a mountain. Also few years back, a B-52 lost 90 per cent of its vertical stabilizer due to turbulence and they were able to land safely.

During refueling in the military we were always up close and personal with aircraft wakes, tails never fell off.

18 posted on 11/16/2001 1:15:33 PM PST by cynicom
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To: FreedomPoster
Didn't hear that about finding the bolts. Bolts would not be loose items if the structure failed. I would not expect to find bolts loose and not attached to the brackets.

The smooth unbroken structural interface where the tail and fuselage meet is very suspect. If it were fastener failure you would expect a clean break. If the fasteners were missing, then one or more brackets would be undamaged. You can't really tell much from the TV picture, so hopefully NTSB will give real data.

The tail looked undamaged for the most part. Likely first to fall off. Cause, maybe turbulence. But seriously, how many tails have fallen off in the last 30 years or so?

Don't overlook ------ that if someone made 'weakening cuts' in the mounting brackets air turbulence could snap it off and detecting those cuts after a crash could be very hard to do. But with detailed analysis, you should be able to tell.

When you have a bracket mounted structure like a tail, and the structure is under high stress, like a tail is, then any failure(intentional or unintentional) in any one of the brackets could cause the entire structure to fail. Airplanes usually have redundancy built in, so it might take two or more mount failures to be catostropic.

But when I saw the virtually undamaged tail fin pulled from the water, my first thought was hmmm.

If the mounts failed, you would expect the tail to have been ripped off with torn metal obvious on all of the brackets. If tampering was the cause, mounts which were tampered with would show little or no ripped/torn metal.

If all mounts show torn or ripped metal, then external forces(turbulence?) would likely be the cause. Home in on the tail fin brackets, major clue likely there.

One other possibilty is rudder failure for one reason or the other. This has happened before with catastrophic results. But I doubt rudder failure would cause the tail to fail by falling off.

I belive if the tail caused the crash, the NTSB will know what was the exact cause. Wether they tell us right away or not is to be seen.

We'll know soon.

snooker

19 posted on 11/16/2001 1:15:39 PM PST by tarpon_bill
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To: tarpon_bill
I remebered something about the Concorde Rudder falling off mid atlantic. This is a from a piece in Time by J F O McAllister, Aug 7th 2000 after the Paris Concorde crash;

Repeatedly in 1991, and once again in 1998, sections of rudder came off while the plane was flying 16 km high at twice the speed of sound

My memory is a bit hazy about the 1991 but I seem to remeber there were chunks the size of a garage door that cam off mid - Atlantic and the pilots when they saw it couldn't believe the plane could have flown.

20 posted on 11/16/2001 1:15:42 PM PST by unending thunder
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