A dumb doubt on stalls

Is it possible for an aircraft to stall and sink nose-up tail-down
instead of pitching nose-down? Or does aircraft design inherently
preclude that?

Thanks in advance,

Ramapriya

On 2006-06-20, wrote:
Is it possible for an aircraft to stall and sink nose-up tail-down
instead of pitching nose-down? Or does aircraft design inherently
preclude that?

Conventional light planes should not do that (i.e. certified, non-canard
designs). However, some rear engined T-tailed airliner designs WILL do
that. It is called a deep stall, and is irrecoverable.

http://en.wikipedia.org/wiki/Deep_stall

has a diagram. Note that in a rear engined T tailed plane, the wash from
the wing will prevent appreciable thrust being made by the engines, so
you can't just 'power' out of it either.

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Dylan Smith wrote

On 2006-06-20, wrote:
Is it possible for an aircraft to stall and sink nose-up tail-down
instead of pitching nose-down? Or does aircraft design inherently
preclude that?

YES

Conventional light planes should not do that (i.e. certified, non-canard
designs). However, some rear engined T-tailed airliner designs WILL do
that. It is called a deep stall, and is irrecoverable.
http://en.wikipedia.org/wiki/Deep_stall

This Wikipedia article leaves a lot to be desired. Stick Shakers are not
related to the deep stall. Stall Warning devices which include stick
shakers are required because of a lack of sufficient natural stall warning
buffet in any airplane. The cure for the Deep Stall was the "Stick Pusher"
which prevented the aircraft from reaching the stalling AOA in the first
place.

has a diagram. Note that in a rear engined T tailed plane, the wash from
the wing will prevent appreciable thrust being made by the engines, so
you can't just 'power' out of it either.

Wing wash had nothing to do with engine power available, the extreamly high
AOA for the deep stall also put the engine cowls at an extream angle from
the relative wind resulting in compressor stalls.

Bob Moore

This Wikipedia article leaves a lot to be desired.

Why not edit it? That's how a wiki works.

Jose
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Bob Moore wrote:

Stick Shakers are not related to the deep stall. Stall Warning devices which include stick shakers are required because of a lack of sufficient natural stall warning
buffet in any airplane. The cure for the Deep Stall was the "Stick Pusher"
which prevented the aircraft from reaching the stalling AOA in the first place

I just started flying p/t as SIC in a Pilatus PC12. Never had any
exposure to a stick shaker or pusher, but the PC12 has both. Stall
training in that plane was *interesting* although I did't realize those
systems were driven by the AOA sensor and not airspeed.

Kingfish wrote:

I just started flying p/t as SIC in a Pilatus PC12.

Neat plane!

I saw one a few weeks back @ MMK. I was amazed at the landing and
takeoff performance.

Kingfish wrote:
I just started flying p/t as SIC in a Pilatus PC12. Never had any
exposure to a stick shaker or pusher, but the PC12 has both. Stall
training in that plane was *interesting* although I did't realize those
systems were driven by the AOA sensor and not airspeed.

I've never flown anything with a real AOA sensor, but it seems obvious
that on any aircraft equipped with one, anything having anything to do
with stall detection would be driven by it. What else would be the
point of having the sensor in the first place?

Roy Smith wrote:
I've never flown anything with a real AOA sensor, but it seems obvious
that on any aircraft equipped with one, anything having anything to do
with stall detection would be driven by it. What else would be the
point of having the sensor in the first place?

Obvious to you, maybe. The Pilatypus was a big step up from a Lance for
me, with exposure to systems I've never flown with before.

Bob Moore wrote in
. 122:

Dylan Smith wrote
Snipola

http://en.wikipedia.org/wiki/Deep_stall

This Wikipedia article leaves a lot to be desired.
Snipola

The beauty of Wikipedia is that YOU can change it.

Brian
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Skywise wrote:

Bob Moore wrote in
. 122:


Dylan Smith wrote

Snipola

http://en.wikipedia.org/wiki/Deep_stall

This Wikipedia article leaves a lot to be desired.

Snipola

The beauty of Wikipedia is that YOU can change it.

Brian

Which is why it leaves a lot to be desired.

Matt