Airbus 380's Massive Structure.

[wsherif1]

A few years ago a young Japanese man sailed a 12 foot sailboat across the Pagific Ocean from Japan to the United States. Due to the minimum mass of the boat, it bobbed up and over the waves and accelerated with the wind gusts.

Now we are considering the mass of the Airbus 380, which will be subject to the wind shear forces of weather and aircraft wake turbulence. The inertia factor of this massive structure will limit the acceleration of the aircraft, and therefore, a high percentage of the kinetic energy in these forces will be absorbed in the structure!

This phenomena is illustrated by the TWA 800 accident. The Boeing 747, another high mass structure, was struck, broadside, by aircraft wake turbulence, and started to break up eight seconds prior to the explosion of the fuel tank! Both cockpit clocks stopped eight seconds after the National Safety Boards's, "End of Data Line", on the FDR Chart. (A 13.5 foot section of the aircraft's keel beam fell out of the aircraft, before the explosion, into the initial debris area.) There was no evidence of fire or explosive damage to any of the many items found in the initial debris area!

The designed mass of the Airbus 380 exceeds the weight at which the aircraft can be accelerated, in sufficient motion to dissipate a high percentage of the kinetic energy in the applied forces.

This inertia factor must be considered in aircraft designs and in Air Traffic Control Standards.

[aviate1138]

Wisherif1 says
"This phenomena is illustrated by the TWA 800 accident. The Boeing 747, another high mass structure, was struck, broadside, by aircraft wake turbulence, and started to break up eight seconds prior to the explosion of the fuel tank! Both cockpit clocks stopped eight seconds after the National Safety Boards's, "End of Data Line", on the FDR Chart. (A 13.5 foot section of the aircraft's keel beam fell out of the aircraft, before the explosion, into the initial debris area.) There was no evidence of fire or explosive damage to any of the many items found in the initial debris area!"



Is this an urban rumour/myth or actual fact?

Does this mean any 747 subjected to the same turbulence will break up in the same way?

Somehow I am reminded of the eminent Victorian Physicist who predicted that passengers would die if they travelled at any speed faster than 30 miles per hour in a train!

B J

" Communication with an engineer is only slightly more difficult than communication with the dead "

[Noise Unit]

wsherif1

I enjoyed your argument, but does it mean that the crew & pax of all the supertankers and floating gin palaces that cross the Pacific (and any other ocean) need to be worried about their safety in heavy seas?

[wsherif1]

Aviate 1138


Your statments,

"Is this an urban rumour/myth or actual fact?"

"Does this mean any 747 subjected to the same turbulence will break up in the same way?"

They are facts fully substaniated by the official reports and the FDR readouts. The NTSB removed essential evidence from the original FDR report!

There were special conditions involved. i.e., A completly stable airmass. The smooth air decreased the diffusion of the aircraft wake turbulence and the separation between the two aircraft was about four miles. The aircraft was struck broadside.by the force of the wake.

I have copies of the FDR readouts both before and after the NTSB removed essential evidence from the FDR Charts. I have enlarged the FDR chart and it shows all the evidence that was removed.

Noise Unit

How many Super Tankers have sustained broken backs in heavy seas? The Japanese sailor in his 12 foot sailboat would have bobbed over the waves.

[LEM]

Wsherif, your fixation against wake turbulence and Airbusses is back!

Now not only it destroyed the AA Airbus at NY (the one which lost its tail because the copilot kicked the rudder insanely), but also destroyed TWA800!

The designed mass of the Airbus 380 exceeds the weight at which the aircraft can be accelerated, in sufficient motion to dissipate a high percentage of the kinetic energy in the applied forces.
Could you please explain the above to me in a language I can understand? :confused:

Thanks!

[kabz]

Given the choice .... an Airbus A380, or a microlite ???

I thought as much !!!

(Go read about manouvering speeds and weights, and your jap sailboat theory doesn't hold water, cos it is on the TOP of the water ... a better analogy would be bamboo submarine vs. a Trident sub...) :}

[747FOCAL]

Lets get this straight..... Other than causing an aircraft to bounce all over the place and be harder to control, WAKE TURBULENTS will NOT cause a commercial sized aircraft to break up.

All aircraft certified by the FAA/JAA are certified to 9g gust criteria and most will probably survive more than that. Lets get real here, aircraft fly into heavy turbulents all the time and people not seat belted in get flung all over the place. These turbulents are every bit as strong, in fact stronger, than wake turbulents.

There is a post here on PPRUNE talking about the 757 on approach a few months ago that not only exceeded the flaps 20 approach speeds by 100+ kts, they pitched the aircraft up then down repeatedly. In other words they super loaded the airframe both positively and negatively and nothing came off. :ok:

Though I don't fly I have been in many many deep stalls in different aircraft and watched what the pilot was doing and listened to the noises the aircraft were making. Nothing short of being real old or running into the ground at high speed will in most cases cause an aircraft to break up.

:hmm:

[wsherif1]

Lem,

Your statement,

"Now not only did wake turbulence destroy the AA Airbus at NY (the one which lost its tail because the copilot kicked the rudder insanely), but also destroyed TWA800!"

Not only did the copilot not kick the rudders insanely, or otherwise, but he did not have any rudder available to assist the full right aileron input, in the recovery attempt!

At some point the 0.3, 0.4 and the 0.8 g forces severed the linkages to the rudder actuators. The rudder was free floating and indicating the rapid and reversing forces striking, not only the rudder, but also the large vertical stabilizer, TURNING IT INTO THE LARGEST FLIGHT CONTROL SURFACE ON THE AIRCRAFT! This large surface, when struck broadside by the wind shear in turbulence, initiated an abrupt left bank into a, "Dutch Roll Maneuver"

Yes it is true TWA 800 was the victim of aircraft wake turbulence.
Why do you think the NTSB removed essential evidence from the FDR Chart, in their coverup?

747FOCAL,


Your statement,

"Lets get this straight..... Other than causing an aircraft to bounce all over the place and be harder to control, WAKE TURBULENTS will NOT cause a commercial sized aircraft to break up."

I hate to disillusion you, but you are not correct.

First see previous reply to Lem, above.

There are a number of cases where the wake turbulence has affected the flight instruments and the pilot has reacted, inadvertantly and put the aircraftt into a vertical dive and the aircraft has come apart in the air. The wake did not cause the breakup however.

In the TWA 800 accident, an aircraft wake turbulence encounter did cause the breakup of the aircraft, prior to the fuel tank explosion! The NTSB attempted to cover up the true cause of the accident by removing essential evidence from the FDR Chart.

[Onan the Clumsy]

Somehow I am reminded of the eminent Victorian Physicist who predicted that passengers would die if they travelled at any speed faster than 30 miles per hour in a train! Yes, but he meant when they went to the buffet car for a sandwich and a cup of instant tea :yuk:

[Colonel Blink]

Please can you provide a link to the report so we can read the theory being proposed - what aircraft would produce a vortex big enough to cause the destruction of a heavy - and does thaty mean ATC are to blame for not providing adequate separation?

[18-Wheeler]

In the TWA 800 accident, an aircraft wake turbulence encounter did cause the breakup of the aircraft, prior to the fuel tank explosion! The NTSB attempted to cover up the true cause of the accident by removing essential evidence from the FDR Chart.

Spot the conspiracy freak .....
(points upwards)

I seriously doubt that a 747 would come apart from a bit of wake turbulence. Having flown them for nearly 3,000 hours through a lot of different conditions I know that they can handle severe turbulence for many hours at a time without any problem at all.

[wsherif1]

KABZ

Your statement,

"Go read about manouvering speeds and weights, and your jap sailboat theory doesn't hold water, cos it is on the TOP of the water."

OK, then put a deep keeled, high masted sailboat on top of the water. In strong wind and heavy sea conditions the heavier mass of the larger deep keeled boat will offer more resistance to the wind and sea forces, which in many cases dis-mast the boat along with other damages. Meanwhile my japanese friend is bobbing along, in his 12 foot sailboat, up and over the seas.

18 Wheeler

Your statement,

"I seriously doubt that a 747 would come apart from a bit of wake turbulence. Having flown them for nearly 3,000 hours through a lot of different conditions I know that they can handle severe turbulence for many hours at a time without any problem at all."

I retired off the 747, Great Aircraft, loved those picture windows!

TWA 800, flying in a completely stable airmass, smooth as glass, little or no dispersion of the wake turbulence, was struck broadside by the wake. A 13.5 foot piece of the keel beam fell out of the aircraft into the initial debris area along with a number of other items. There was no evidence of fire or exlosive damage to any of the items in this area! The cockpit clocks stopped eight seconds after the NTSB's, "END OF Data Line"!

The NTSB removed essential evidence from the FDR Chart in their coverup. P.S. I have copies of the FDR Charts both before and after the removal of the data, along with an enlarged copy of the FDR Chart which shows the data that was removed!

[747FOCAL]

wsherif1,

You may be some sort of a text book cowboy that relies on the wild fantasy of speculation, but I have been there. I know exactly from being on more abuse flight tests than you will ever know. I am not going to masterbate my ego in front of all these professionals and stoop to an unprofessional level. You just haven't been there. There are wind phenoms that will destroy an aircraft, but wake turbulents are not one of them. Not in a commercial sized aircraft anyway. The chances of "finding" one of these wind phenoms is as rare as finding a gold brick on the ground in skagness.:E

Aircraft experience wake turbulents and various other turbulents on a daily basis. We would have seen more breakups if you are correct. I wish you were right. It would make a lot of bad things easier to live with.

The fact is, no matter what you do, eventually something bad is going to happen. It's then that you thank god the guys up front know more about what they are doing than any other pilot on the face of the planet at that moment, or at least you hope they believe that. Confidence and guts, combined with much knowledge and experience is all you got once your up there. :ok:

[Volume]

What are we discussing here ? Gust loads on large Aeroplanes or 747 conspiracy ?
Looking at the thread title I assume the first.

747focal, where do you take the 9g gust from ? Never heard of it.
Normally you assume gusts of 56 ft/sec at sea level to 44 ft/sec at 15000 ft to 26 ft/sec at FL 500 at cruising speed Vc, and half of it at Vd.
Gust load calculation is a real hard thing, and you have to rely on some assumptions like gust allevation. This gust allevation is assumed to be depending mainly on wingspan and air density, therefor strongly variing with altitude. The gust load calculation also depends on the slope of the Cl vs alpha curve, and the stiffness of the wing. Derived from measurements in older four engine prop transports, there is an emperical formula aviable, which is quite conservative and takes into account the typical stiffness of these old design wings.
More information can be found in
NACA-Report 997 (http://naca.larc.nasa.gov/reports/1950/naca-report-997/naca-report-997.pdf) , NACA-Report 1206 (http://naca.larc.nasa.gov/reports/1954/naca-report-1206/naca-report-1206.pdf) , NACA-Report 692 (http://naca.larc.nasa.gov/reports/1940/naca-report-692/naca-report-692.pdf) or NACA-Report 1162 (http://naca.larc.nasa.gov/reports/1954/naca-report-1162/naca-report-1162.pdf).

To the best knowledge about gust loads today, it can be said that increasing the planes mass generally reduces maximum gust loads. On the other hand there are some problems (or better call it some aspects) with gust loads in the certification process, this forced Airbus and the authorities to agree on a modified rule, assumimg larger gusts than previously contained in the JAR/FAR25. The largest extent of a gust was assumed to be 12.5 times the mean wing chord, but not greater than 350 ft (which is 12.5 times the chord of a 747). This has been adopted to the new larger wing of the 380, the value has been increased to 435 ft, while 12.5 times the A380 length would have been only 425 ft. So some more safety reserve has been planned in.

I won´t support the idea, that a larger structure ´absorbes´ more energy. Larger structures tend to be not only heavier, but also much stiffer. Especially the large Doubledeck fuselage should be much stiffer in bending, than the 747 or A340-600 fuselage of similar length. And as the energy is force multiplied by displacement, the stiffer structure ´absorbes´ less energy ! (loading a stiffer spring with the same load results in lower energy absorbtion).

For new (and undoubtfully interesting) facts of the TWA800 crash, better start an extra thread.

[LEM]

After reading the Silk Air thread, I'm afraid Wsherif really will entertain us on this one. :zzz:

[DanAir1-11]

My I offer 2 points.

Firstly, From what perspective do you question the integrity of the A380 design. Are you of an engineering background? and if so, could you offer any reason that the team of design engineers at the Airbus bureau, with their immense experience, resources and technology have failed to account for the pointsthat you have raised.

Secondly, as another user has already pointed out, Wake turbulence is not going to destroy an aircraft. I say this with the following qualifications - that is unless it is at a point in flight where it is either at minimums with a crew who for whatever reason fail to detect it in sufficient time, or, in the initial climbout immediately after climbout, both of these scenarios involve damages or ultimately destruction with ground impact at the causative factor, Wake turbulence itself will not break up an aircraft.

Airbus simply would never receive COA if the suspected 'flaws' you suggest were possible, indeed Airbus would not have advanced the design past the point where anything such was proved to be conclusive.

[Captain Stable]

I read this thread yesterday with a certain amount of wariness and scepticism. I decided to let it run, hoping that a good discussion on alternative theories might emerge.

Having now re-read it, I feel it is not conducive to the aims of the TechLog forum - which is to educate and enlighten.

Conspiracy theories have no part here, nor do personal invective and insult.

I am therefore closing this thread. If anyone wishes to object, feel free to PM or email me with your reasons. If they are sufficiently cogent and show a genuine reason within the aims of the forum I will reopen it.