Yes Terrence, AOA.  No mental exercise necessary if one has an AOA sensor.  And, Charles' comment is a bit off.

 

In level flight, the wing AOA provides sufficient lift (wing loading) to equal the effect of the force of gravity (1 G) on the aircraft weight (W).  Thrust overcomes drag to result in forward speed. 

 

In a descent at the same speed used in level flight, lift is less than W and either power (thrust) is reduced or drag is increased.  Remember that G is just for relative reference.

 

Again, in level flight at the same power, but in a coordinated banked turn, the wing AOA has been increased to add enough bank angle lift necessary to maintain 1 G with respect to the vertical.  I.E. The wing load must be increased to keep the plane at the same altitude - The lift has to equal the weight divided by the cosine of the bank angle.  To visualize:

 

 

One could redraw this with force vectors to see it better.  Of course, because of increased load, the induced drag is also increased.

 

Finally, in a coordinated banked turn without power and even further drag from other bits and pieces, descent (glide) will occur unless the AOA could be increased provide sufficient lift to offset the vertical component (the pull of gravity).  But, there is a limit AOA at which a stall would occur - thus descent.  In a banked turning descent at a certain speed (best glide for the conditions), less lift is required, thus less load on the wing, thus a lower stall speed than a higher load.  This supports the statements made by both Dave Morss and myself.  Dave's point is that large bank angle conducted at a optimal speed shortens the time (distance) and lessens the altitude loss plus in the descent the stall speed is not as great as that in the same bank holding altitude. 

 

An optimal speed is somewhere above stall speed.  Factors affecting stall speed are load and drag (wheels, flaps, prop, etc.) - hence the requirement that you point the nose down making use of kinetic energy rather than gasoline to keep up the speed.

 

Uh, the Aeronautics for Naval Aviators is silent on powerless descending turns (maybe a glider tech manual would be more informative).  I have included the simplified Excel spreadsheet to give you a feel for some of these parameters before testing at high altitudes.

 

Blue Skies,

 

Scott Krueger

 

Angle, angle, angle.  Angle of stall is constant, no matter what.  Simpler, not requiring mental gymnastics.

Terrence.

Sent from my iPad

On Jun 3, 2013, at 7:03 AM, Charles Brown <browncc1@verizon.net> wrote:

In a straight ahead descent, the wing is producing 1g lift and the stall speed is the same as in level flight.   You guys may be thinking of the change in stall speed when *initiating* a descent (pushover, less than 1g for a moment), or when *terminating* a descent (pull-up, or flare, momentarily more than 1g).  

On Jun 2, 2013, at 2:18 PM, Sky2high@aol.com wrote:

Dave, et al,

 

In a descent, the stall speed is different because the wing is not lifting the same weight as it would be in level 1-G flight.  However, that only accounts for the vertical component.  The hi-G turn (like 70 degrees of bank) is still adding sgnificant load to the wings.

 

<...>

 

In a message dated 6/2/2013 1:08:44 P.M. Central Daylight Time, morss@pacbell.net writes:

in scotts reply he includes a graph of stall speeds vrs bank in a level turn.remember this turn around maneuver is not level but descending so the stall speed doesn't increase as much as the graph but if you get ground rush and try to arrest the descent rate in the turn you will probably stall
more reason to practice at altitude and see if this is something you might want to include in your bag of tricks
dave
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