View Full Version : Deep Stall - Why would the airflow block hinder the elevator

11th Mar 2009, 10:57
If the air is not reaching the tail section, wouldnt the tail then drop and thus dropping the nose and recovering...like a low tail elevator on a piper?
I know I'm going to be wrong but I can't think why... :)

Concept to Reality (http://oea.larc.nasa.gov/PAIS/Concept2Reality/deep_stall.html)

11th Mar 2009, 11:59
Im going to take a stab at this.

I would imagin that with a swept wing aircraft (as the T-tails are) with the movement of the center of pressure forward (due to tips stalling first) that the overall pitching moment is nose up as the center of pressure moves infornt of the c of g.

As the tail is in a turbulent airmass then its effects will be minimal.

Waiting for the corrections.......:O


11th Mar 2009, 12:10
The air is reaching the tail section; the problem is that it is a disturbed, turbulent airflow rather than laminar, and thus not given to allowing as much negative (or positive) lifting force to be imparted to the control surface.

The answer is really in the link you provided. Many a/c with T (and sometimes +) tails are fitted with stick pushers to prevent the deep stall condition.

11th Mar 2009, 13:54

spot on!!!


11th Mar 2009, 16:22
Thanks Tarq and Nick, so it's the turbulent rather than just no air...that makes more sense :)

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