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Tail Stall vs. Wing Stall

Old 03-31-2010, 06:36 PM
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Default Tail Stall vs. Wing Stall

I've been getting ready for my Comm SEL ride, and one of the things that I want to be proficient on is being able to recognize whether we're in a wing stall or a tail stall (Colgan 3407 anyone?). I was looking for a little help on how to tell the difference between the two as far as behaviors of the airplane go. How do I tell if I'm in a tail stall vs. a normal wing stall, and (most importantly), how to recover from a tail stall if it is one. Thanks in advance everyone.
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Old 03-31-2010, 08:34 PM
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Originally Posted by A320fan View Post
a tail stall (Colgan 3407 anyone?).
Colgan wasn't a tail stall.

Originally Posted by a320fan
I was looking for a little help on how to tell the difference between the two as far as behaviors of the airplane go.
The main wing will result in a buffeting that is felt throughout the aircraft. You have likely noticed it in your power off stall work.

With a tail stall you will feel that buffet in the yoke. It may feel particularly sloppy or jolt from the buffet (a near stall condition).

Originally Posted by a320fan
How do I tell if I'm in a tail stall vs. a normal wing stall
See above. Also, the nose will fall forward rapidly. You should wonder, what is the aerodynamic difference between the main wing and horizontal wing?

Originally Posted by a320fan
and (most importantly), how to recover from a tail stall if it is one.
Pull back.
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Old 03-31-2010, 09:24 PM
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Aerodynamically speaking, a tail stall occurs when the eddy produced by the ice on the tail moves far enough aft to interact with the elevator thus producing a control buffet. For this to occur, you generally need a higher speed than would be required for a wing stall, even above the elevated stall speed for the wing in such conditions. This video may be a bit dry, but it has some great info on tailplane icing.
http://video.google.com/videoplay?do...3060735779946#
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Old 03-31-2010, 09:30 PM
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When you practice power off stalls, if you keep pulling back after the buffet and stall warning horn, eventually the nose drops aggressively. My understanding was that is the tail stalling and the aircraft loosing that downward force from the tail causing the heavier nose to fall forward. Is this the correct logic? If that's the case, we recover by pushing the nose FORWARD to break the stall. Something is not sitting right with me...
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Old 03-31-2010, 10:59 PM
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Originally Posted by 9kbud
a tail stall occurs when the eddy produced by the ice on the tail moves far enough aft to interact with the elevator thus producing a control buffet.
This makes it sound as though a tail can only stall from icing. I just wanted it to be known that that icing isn't the only way a tail stall can occur.

Originally Posted by snippercr View Post
Is this the correct logic?
No. You basically said a tail stall is an excessive wing stall. However, the horizontal stabilizer is a wing, mounted inverted. Knowing the tail is an inverted wing we can assume a stall on this inverted wing to require inverted control inputs from an upright (main) wing stall.
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Old 04-01-2010, 12:20 AM
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So how would you get a tail stall without ice contamination?
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Old 04-01-2010, 02:05 AM
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Like the other guy said, the stab or elev is an upside down wing. Normal stall is caused by exceeding a certain positive AOA. The tail will stall when you exceed a certain negative AOA. For instance, when you put out 10 degrees of flaps in a 172 remember noticing that the nose wanted to pitch down. obviously all aircraft are different. There is a good nasa video on tail stalls. I reccomend searching for it. Also like the other poster said. Its an upside down wing, so recovery would be opposite of normal. Hope we helped you.
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Old 04-01-2010, 03:23 AM
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Originally Posted by snippercr View Post
When you practice power off stalls, if you keep pulling back after the buffet and stall warning horn, eventually the nose drops aggressively. My understanding was that is the tail stalling and the aircraft loosing that downward force from the tail causing the heavier nose to fall forward. Is this the correct logic? If that's the case, we recover by pushing the nose FORWARD to break the stall. Something is not sitting right with me...
No, that pitchdown is due to the aft movement of the wing's aerodynamic center once it stalls.
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Old 04-01-2010, 05:07 AM
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Tail-Stall would also be recognized by lack of effectiveness of the elevator due to the buffeting air. I could be way off, but I recall this happening to me once while loaded with ice on approach.
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Old 04-01-2010, 06:32 AM
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On most airplanes a tail stall should not happen in any normal or most abnormal flight conditions unless ice or mechanical damage/failure changes the shape or designed position of the horiz stab.

The indications as mentioned above are yoke buffeting and nose pitch down. Tail stall is likely to occur when flaps are lowered or power is increased due to the shift in CG which causes a chain of events resulting in the elevator exceeding COA.

IIRC, the corrective action in general (see your POH/AFM/SOP for actual procedures) is to pull back on the yoke in order to reduce tail plane AOA, return flaps to their previous position if a flap change triggered the event, and reduce power if you can do so safely.
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