Elevator Stall?

[JSky26]

So I was practicing stalls with my instructor in a 172RG today with a new student pilot riding along in the back. We were a little heavy and it was damn near 90 degrees out. Transitioning from slow-flight into a power-off stall, I closed the throttle and raised the nose. I knew that this bird wouldn't hold for long and she didn't. I got the buffet and the stall. It was very clean, no slips or skids...but as I raised the nose quickly and added my power I lost all elevator control for a second or two and the airplane broke to the left on me. It was a strange feeling since that has never happened before. Did I just experience an elevator stall? Was this due to a different CG than I have been used to with the occupant in the back?

Let's hear it CFIs...

 

[Alamanach]

...but as I raised the nose quickly and added my power I lost all elevator control...

I assume you meant to say lowered the nose?

 

[JSky26]

I assume you meant to say lowered the nose?

Yes, sorry my typo. I lowered the nose and added power and as the nose was coming up, was when I lost my elevator control effectiveness.

 

[Waldom]

By "elevator stall" are you are refering to the horizontal tail stalling?

I suspect what you encountered was a secondary stall [of the wing, not the tail ] that was created by pulling the yoke back a bit too quickly and causing an accelerated stall.

Because of a shorter moment arm, an aft c.g. does decrease the effectiveness of the rudder and elevator controls slightly but with the loading you described, the c.g. would be well within the limits of a 172RG and would not cause what you experienced.

 

[JSky26]

Ok, that sounds about right. Someone mentioned an "elevator stall" to me and it didn't sound right. Thanks for clearing it up.

 

[aucfi]

I agree with Waldom except for the accelerated stall part. Secondary stalls occur when trying to recover from a stall too quickly when you do not have sufficient airspeed.

I doubt the elevator had stalled especially after adding power for the recovery. The slip stream from the prop increases the tail surfaces effectiveness at lower airspeeds. This is beneficial but also bad because it allows you to easily pitch up beyond the critical angle of attack and enter a secondary stall before adequate flying speed is attained.

au

 

[Tonala2k]

I Fathom, that an elevator stall would result in a very rapid nose down pitch attitude. The horizontal stabilizer and elevator are there to keep the nose up. I fathom that it works hard to do so (considering the arm). That's easier to do with an Aft CG (so long as you're adding weight behind the center of lift, and in a 172RG the back PAX are behind). Not as much load required on the stabilizer, not as much angle of attack required, thus less likely to stall with a back seat pax. In a 172S I was at Gross and the forward edge of the envelope, with nothing behind the pilot seats. The stall felt normal to me.

 

[Kream926]

i FATHOM the question as to why you didnt ask your instructor when this happened?

 

[JSky26]

Actually I did, he told me it was a secondary stall. Just wanted to get some others views...thanks again

 

[Amish RakeFight]

The nose would drop steeply if the tail stalled. Sounds more like a secondary stall. You'll feel the same sensation (no response) if you use full aileron to correct a dropped wing during a power-on stall.