Can somebody explain what is the impact of CoG position on stall recovery. I heard that stall speed is higher with forward CoG comapared to aft CoG, but does it have influence on stall recovery? Is it more or less difficult with some CoG position?
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It sure does, and that is the reason we don't abuse aft CG limits.
An excessively aft CG shortens the torque arm of the tail pitch down forces and lengthens the torque arm of pitch up forces ahead of CG, including more of the wing.
As a full stall develops, the nose of the fuselage will also generate lift in addition to its area drag as the plane sinks, making it harder to "bring the nose down" and unstall the wing by reducing its AOA to the relative wind.
By design, a larger tail adds safety if one is foolish enough to test aft CG limits. A speed brake or parachute is another line of defense.
The effect of forward set CG on stall speed may arise from the need to generate a bit more lift with the wing to counteract increased tail downforce but remember most tail "downforce" is used to set wing AOA, only a little more is needed for forward CG.
Forward set CG will also make it harder to lift the nose in slow flight, which may actually drop the nose before it stalls if elevator is small or travel is limited and the horizontal stabilizer is large. The B-52 was designed in this manner for obvious reasons.
Each plane is different, and even a docile trainer like the Cessna 152 can be dangerous if aft CG limit is exceeded.
Robert DiGiovanni
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