CNN strikes again!

[airboatr]

well grab his shirt sleeve ,

when Ice (in general) forms on a wing and the body of the plane does it
form in such a way that it conforms to the air flow on the surfaces
so the plane keeps flight (to a certain point.)
If that’s the case then would the flaps , like change the whole (i don't know the word here)
aerodynamic characteristics to the point they turn it into a "hurtling piece of metal" when set out .

The boot,
I can see how easily that would happen, I lived in the stuff many years and have seen natural ice configurations
create some wacky shapes

[TSR2]

Thanks for that Leif. Makes sense. If they were particularly prone to icing issues I wouldn't have thought SAS would have flown them (not withstanding the SAS undercarriage issue.)

[DispatchDragon]

Thanks Ben

Joe - I have seen ice formation on a wing in flight that looked like a cobblestone road - Im not going to quote figures but the degradation due to ice
accretion is rapid and terminal -- its a combination of the disruption of the airflow over the wing AND the weight of the ice - both contribute to
massive changes in the aerodynamics of an aircraft - flaps produce lift yes, but they also contribute to drag as well - given the combination of
the weight of the ice (imagine taking a 55 gall oil drum and coating it in 2-3 inches of ice and then tryng to lift it - the weight of the drum would be
doubled) , plus the aerodynamic disruption cause by the ice , then add an aircraft slowing to approach/landing speeds and you have recipe for
disaster - I hope and prey that Im wrong , and that the NTSB find something else.


Leif

[airboatr]

ok thanks,
the drag effect was what I was after i guess.

[markw]

I'm reluctant to perpetuate any speculation, but more out of curiosity, if it was the case the ice had somehow formed in a way the pneumatic de-icers couldn't remove it, would electrical or hot bleed-air systems have worked better? I think I'm correct in thinking that turboprops tend to have pneumatic systems because their engines are unable to be used for hot air de-icing, in which case does that mean an aircraft with hot-air de-icing might have been less affected?

Whatever the situation, it is extremely sad and I do wonder if it is a similar case to the American Eagle ATR crash of a few years ago?

By the way, wasn't the theory regarding the SAS Q400 undercarriage problems that they spent a lot of time parked in the open at Copenhagen getting a nice salty sea-spray shower each morning?

[Chris Trott]

On one of the other forums I follow (WIX), several people whom have a lot more time flying than I will for a very long time, brought up the idea of potential tailplane stall. One of them put up this link that states that it's not necessarily the addition of flaps that caused the tailplane stall as much as the simple change in configuration and reduction in speed to do so -

http://video.google.com/videoplay?docid ... 0735779946

[DaveB]

Interesting vid Chris.. tks for posting

ATB

DaveB :tab:

[simondix]

They are not called the Gutter Press for nothing!

[DispatchDragon]

Interesting Vid Chris

It brings up something I asked the ex Horizon guy - was is there an interlink between the flaps and the stab trim?
the 400 has such a long pitch arm - I wondered if there was a physical connection - which would make your video
all the more telling - they set 15 flap the stab trim moved and the tail plane stalled plus the weight of the ice...........


Again this is all supposition - but I shall be interested to read the NTSBs findings

Leif

[TSR2]

That was an excellent Video Chris, and well worth viewing. Many thanks.