The following is condensed from an article published in the Autumn
edition of the GASCO Flight Safety Magazine.
Acknowledgements and thanks: GASCO/Gerry Humphreys
Loss of control is increasingly evident in fatal accidents in both GA
and commercial operations, and the key to avoiding it is Angle of Attack Awareness.
For those wanting to learn to fly in as short a time as possible
simulators are used to teach standard and emergency procedures, and to minimise
costs. However, they do not recreate the effect of “G”, without which the
trainee is missing out on experiencing instruction in an important skills area.
Thus many trainees rarely get to fly a turn above 450 angle of
bank, or a pitch of 200.
AoA is important in determining whether a wing flies or not, so
understanding it is vital if we are to understand what is happening when we
pilot an aircraft. LIFT and DRAG are directly related to SPEED and AoA, but whereas we seem to
concentrate on speed, AoA is the more fundamental
concept to be grasped; because STALL is related to AoA alone. A good Instructor will thus
introduce the concept of AoA at an early stage of training.
Primary Elevator effect:
Stick
back, AoA of wing increases, lift increases, aircraft climbs
Secondary Elevator effect:
Stick back, AoA of wing increases, drag
increases, speed decreases
Speed .v. AoA relationship:
High speed, Low AoA; Low
speed, High AoA
Primary Aileron effect:
Change in the LOCAL AoA, which alters Lift and Drag in
their own Area. Wing rises,
Lift & Drag increase; Wing falls, Lift & Drag
decrease
Secondary Aileron effect:
Yaw in
the opposite direction to the input roll. In an established bank,
an aircraft will first
slip then yaw in the same direction as the
input roll, but at this stage the ailerons are actually
NEUTRAL. Any subsequent
slip & yaw will be an effect of Angle of Bank & Stability,
not aileron
control input
Keep the ball in the middle:
If not, the ailerons will be
deflected, with one wing at a higher AoA than the other.
Approaching a
critical overall AoA, the down-deflected aileron will stall first
Spin training:
Of
limited value in the real world, as most fatal spins occur too close to
the ground to enable
recovery. Better to train prevention by means
of realistic stall training incorporating AoA
Awareness.
Feeling the Force:
Much
steep-turn training is done at 450 AoB, but training at 600 AoB
as well is beneficial
in two ways:
- It demonstrates that the increased lift needed demands an increased AoA:
Stick back further = more
lift = more drag = more power required
- The
pilot can experience what 2G feels like, and if on pulling the stick back you
feel 2G,
you have enough lift to fly. You will not stall unless speed reduces,
so given sufficient
terrain clearance and the application of correct technique,
recovery is achievable. If you
don’t feel the force you need more speed or a lower
AoA for
the lift equation to work
FLY SAFE!
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