Stalling and Turning

[djpil]

From another thread where some-one got into trouble for getting off topic:Vote 1 djpil for CASA CFII. (Chief Flying Instructor Instructor)
BTW are they, the flying training industry, still running the Master Instructor programme.

I see from the March/April Australian Flying (which I bought) that "Two CASA flying operations inspectors who are participating in the CASA Flying Training Specialist Group (FTRSG) program to upgrade flying training ..... have prepared a scientific paper on the subject" of the SSP concept - stall-stick position.
About a year ago I was discussing this with a local FOI. I asked him if he was aware of the FAA's AC on the subject - nope.
.... pilots have not been receiving the stall/spin awareness training mandated by the FAA (http://www.fcitraining.com/article12_fci_training_jan04.htm)
Certainly good to relate stick position to angle of attack and the stall. What's missing from the article is the other independent variable in the equation - centre of gravity. Same aeroplane, different c.g. will give two different stick positions for the stall. Trouble is that most stall training is done at pretty much the same c.g. position. Do your training in a 172 and it is at forward c.g. however it behaves a lot different at aft c.g. and the stick position for the stall will be different. The article mentioned a stall accident in a Lance.
The FAA in the USA permits instructor renewals by spending a weekend at a Flight Instructor Refresher Clinic. An opportunity for instructors to share ideas and learn from experienced people such as Phil Unicombe (per that article).

[Arm out the window]

Stick position would be one of the lowest things on the list to suggest an unaccelerated stall; how about -
high nose attitude
low and decreasing IAS
sloppy controls
buffet ... not to mention stall warning, if fitted

as you say, c of g will dictate stick position, therefore not a useful indicator of impending stall.

[Kickatinalong]

You DON'T need a nose high attiude to stall an aircraft. It can be stalled in any attitude. Remember the relative air flow stuff?
Kickatinalong.:ok:

[Arm out the window]

I was just referring to a wings-level unaccelerated stall, for which you'd generally need a high attitude.

[Bendo]

I am pretty sure the title of this thread is "stalling and TURNING" in which case - IMHO - stick position IS relevant.:hmm:

[Captain Sand Dune]

Is the question referring to elevator position or aileron position (or both, perhaps?). As AOTW says, CoG (and CoP with flap deflection) will affect elevator position.

Although I generally concur with AOTW, I would ensure any significant aileron input was removed during a stall i.e. stick centrally forward etc...etc.

[certifs]

"I was just referring to a wings-level unaccelerated stall, for which you'd generally need a high attitude."


But accidents just about never happen from this situation. The slow, unco-ordinated turn is what does people in.


Some good few years ago Mike Valentine in the gliding movement wrote a number of articles regarding spin awareness training (they still do it pre solo in gliders). At the time, he was advocating instructors demonstrated the typical slow skidded turn to students. If done properly many (not all) gliders could go from what looked like a normal attitude, normal airspeed, balanced turn to a fully developed spin, with the _only noticeable_ warning being "progressive rearward movement of the stick".


Very convincing when done properly, but very difficult to do consistently. Of course some people manage it every now and then without trying too hard. Thats the problem.


Certifs

[kalavo]

Stick position is definitely relevant!!!

An aeroplane wing will always stall at the same Angle of Attack, regardless of airspeed or nose attitude - something you'll learn if you do an aerobatics endorsement

The stick position is our primary means of controlling the Angle of Attack of the wing in flight - move it back and forth and you'll change the AofA of the entire wing, move it sideways and you'll control the AofA differentially.

CofG and Power Setting also have an influence on our AofA because in most aircraft they change how effective the tailplane is (shorter/longer lever arm and more/less airflow over the wing).

Good book on the subject if you're interested is Stick and Rudder by Wolfgang Langewiesche. It was first printed in 1944, but not a lot has changed since then.

[Captain Sand Dune]

If done properly many (not all) gliders could go from what looked like a normal attitude, normal airspeed, balanced turn to a fully developed spin, with the _only noticeable_ warning being "progressive rearward movement of the stick".


Not sure I understand that. The above description sounds like the spin was set up from 1g flight, so how could the IAS be desribed as normal. Surely the IAS must have been decreasing toward the basic stall speed. In that case the low and decreasing IAS would be pretty obvious indicator.
Obviously an aircraft can stall at a higher speed than the basic stall speed, but that would mean that g must be increased - again, another fairly obvious indicator when coupled with IAS.

Was never taught to note stick (elevator) position when stalling, and have never taught it. Furthermore I have never seen any reference to stick position in any instructor manual when dealing with stall recoveries.

[Arm out the window]

Yeah, good on you, Bendo.
The word 'turning' in the thread title is the only reference to it; the link in the first post doesn't talk about it, and the first post discusses stick position vs. c of g.
So perhaps I've missed the thrust of the discussion, but you can stick your sarcastic smiley.

[Oktas8]

I have mentioned the stall stick position to aerobatic students on occasion - as a point of general interest.

But the stall stick position does depend on power, especially if the tailplane is in the slipstream, and even more especially in a high rate of g onset situation - that is, a zoom to vertical climb for example.

So would I use it for ab-initio, pre-PPL power fixed wing stall awareness? Well, I haven't yet...

regards to all,
O8 :)

[djpil]

To continue the discussion. Some of us had noted that stalling while turning in take-off or departure configuration is no longer on the test forms. Why did this happen? I see that it is still required in the USA, for example. Interesting to see how much more is required in the USA in the way of stalling exercises and awareness of spins.

[AEIO-540]

For what it is worth here are my thoughts on stall stick position.

It is good for a very basic way of thinking, but it really doesn’t work as a one stop rule for an aircraft as IT WILL CHANGE in every aircraft under different situations.

It will only work for one single configuration as soon as you change things such as weight or C.G so will the stall stick position. Once you put flaps down or up this will also change stall stick position. Now if you where to put the undercarriage down on a low wing aircraft with the undercarriage in the wings you have changed the shape of the wing and therefore the stall stick position.

Also side slipping or skidding changes the way that the air will flow over the wing and therefore this will also affect the stall stick position.

I believe that it is silly to whole say that the stall stick position will always be the same. It is a very bold statement in my opinion.

:ok:

[Captain Sand Dune]

AEIO-540,

Exactly. Stick position as an indicator of an impending stall is at best a peripheral consideration, and in practice probably more of an unhelpful distraction.
However during a 1g stall recovery I do get Bloggs to feel how much the stick moves forward to produce the attitude change needed to unstall the wings.
When teaching maneouvring on the buffet I get Bloggs to notice that the elevator position does not appreciably change while maintaining the light buffet.