CFI Stalls

M

meritflyer

Well-Known Member
Going out with a guy to practice some maneuvers for his CFI single engine add on.

See if this is the best way to teach the secondary stalls -

Set config for power off, speed down, power out and hold altitude, stall occurs, increase power but intentionally pitch up excessively to stall again.

Any thoughts?
 
A-yup. Just exagerate the pitch up attitude on the recovery to stall again to simulate an over-agressive recovery.
 
caliginousface said:
I wouldn't even touch the power for secondary stalls.
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There are indeed multiple ways to do the demonstration.

==============================
SECONDARY STALL

This stall is called a secondary stall since it may occur after a recovery from a preceding stall. It is caused by attempting to hasten the completion of a stall recovery before the airplane has regained sufficient flying speed. [Figure 4-7] When this stall occurs, the back-elevator pressure should again be released just as in a normal stall recovery. When sufficient airspeed has been regained, the airplane can then be returned to straight-and-level flight.

This stall usually occurs when the pilot uses abrupt control input to return to straight-and-level flight after a stall or spin recovery. It also occurs when the pilot fails to reduce the angle of attack sufficiently during stall recovery by not lowering pitch attitude sufficiently, or by attempting to break the stall by using power only.
==============================
FAA Airplane Flying Handbook

Personally, I prefer the powered version only because I think it's a better lesson that pitch is the primary factor in stall recovery - pitch alone will do it; power alone won't (at least in most light aircraft).
 
MidlifeFlyer said:
There are indeed multiple ways to do the demonstration.

Personally, I prefer the powered version only because I think it's a better lesson that pitch is the primary factor in stall recovery - pitch alone will do it; power alone won't (at least in most light aircraft).
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Oh for sure. I'm kinda confused though, you say you use power to show that pitch alone will allow the airplane to recover?
 
MidlifeFlyer said:
There are indeed multiple ways to do the demonstration.

Personally, I prefer the powered version only because I think it's a better lesson that pitch is the primary factor in stall recovery - pitch alone will do it; power alone won't (at least in most light aircraft).
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Interesting. I find that using full power in most light trainers causes you to have to jerk the nose up quite abrubtly because of the up thrust from the prop, and to get a secondary stall, you really have to be very obvious about yanking the nose back up almost immediatly after recovery.

Power off isn't as bad, but you stll have to pitch back up rather quickly.

To me, the best demonstration is with about half power; not enough to give much up thrust, but enough to give good elevator authority, so that a smaller pitch-up change will result in re-entering stalling angle-of-attack.

Of corse, like all stalls, they should be practiced in all power and flap configurations.
 
nosehair said:
To me, the best demonstration is with about half power; not enough to give much up thrust, but enough to give good elevator authority, so that a smaller pitch-up change will result in re-entering stalling angle-of-attack.
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I like that.

caliginousface, that power demo for a secondary stall is juxtaposed with stall recovery with no power at all (without the secondary stall) or a falling leaf.
 
meritflyer said:
Set config for power off, speed down, power out and hold altitude, stall occurs, increase power but intentionally pitch up excessively to stall again.
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I find the power off stall recovery the most realistic setup for secondary stalls. New students will drop the nose too much during recovery, see the ground and then pull back too aggressively. This also ilustrates that stalls can happen with a "nose low" attitude, which is an important concept.
 
Yes the falling leaf stall is very interesting. I learned it during my private training in a pa-38-112 (Piper Tomahawk). Great little airplane. My instructor covered up the vsi and altimeter and told me to hold the airspeed (don't remember what airspeed he told me to hold... it was a long time ago) and the airplane was shuddering and buffeting and such. Then he uncovered the vsi and altimeter to reveal that we were dropping out of the sky pretty quickly. Then he told me to turn around and look at the T-tail. It was skaking pretty violently. I was impressed. Very neat maneuver. Also teacher very positive aircraft control. : )


CFI, CFII, MEI
 
Never heard about this falling leaf stall. . . anyone want to elaborate further on what conditions would have to be met for it to occur?
 
surreal1221 said:
Never heard about this falling leaf stall. . . anyone want to elaborate further on what conditions would have to be met for it to occur?
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It's a power-off, straight ahead stall in which you do not recover. Power remains at idle, the stick is kept back, and the rudder is used to maintain coordination, so there is no spin. It demonstrates coordination and the practical aerodynamics in a stall.

In most aircraft, the net result is a bobbing up and down of the nose as the airplane stalls, the nose drops, the airplane unstalls, the nose rises, the airplane stalls, the nose drops... etc, until you recover. Hence the description as a "falling leaf."

Since there is a delayed recovery, you need more altitude than a "normal" power off stall-recovery sequence.
 
The piper Tomahawk performs the falling leaf stall without the bobbing. It's pretty much just kept in the same exact attitude in a constant stall with as little forward movement as possible. The tail shakes and shutters a lot too. Kinda scary. Great for teaching minimal control inputs and coordination at the same time.
 
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