Old 4th Nov 2015, 20:09
  #943 (permalink)  
Join Date: May 2010
Location: PLanet Earth
Posts: 798
Originally Posted by Leightman 957 View Post
I find it odd that the discovery of the HS pieces (I still haven't seen pics of both) has been met with quick general prune agreement that they failed in direct shear due to aerodynamic forces from tumbling at Speed
I doubt that once separated from the rest of the fuselage forces would be sufficient to shed the feathers. The tail assembly is very strong and the mass of that section behind the RPB is not very big. Moreover I don't see why that section should 'tumble' when separated. It is basically a dart and would probably stabilize quickly.
IMHO that shearing of the HS would only happen as long as it was still attached to the fuselage.

....while at the same time no one disputes a nose down rotation, negative G tuck by the fuselage minus tail at the very same airspeed, where the wings very apparently did NOT fold up....AND that forces on the wings were sufficient to strip of both engines off the wings. Why did the wings remain intact spanwise?
Relevant question!

So, let's have a look at it:
The Event started at ~250kts IAS but according to the FR24 data Speed dropped quickly to below 200kts. I don't know the exact max cl of the A321 wing in negative directions, but 1g stall Speed of the inverted wing should be somewehere around 150 - 160kts min. I don't know the max negative g the A321 wing will take but let's assume 2,5g. That would mean ít would reach its lift limit at 240 - 250kts. In other words: at the speeds we are talking about it is entirely conceivable that the wings didn't shear off even in case of a bunt over pretty quickly after the initiating Event.

So a possible Scenario remains: Something caused a rapid and massive excursion of the THS/Elevator. This causes the HS to fail. Aircraft starts to bunt over putting enormous load on the VS and rear fuselage, causing the fueslage directly aft of the CWB to collapse.
Possibly the otherwise historically almost undestructible VS hits parts of the fuselage/structure in this disintegration process. and fuel lines to the Center tank being severed (/the Auxiliary Center tank disintegrating -did this one have one installed?) releasing fuel into the open tube of the rear fuselage - being ignited by sparks from severed electrical lines.

Not saying this was the case, just it still appears to remain a conceivable Scenario within the limited Facts we have so far.
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