Flick rolls (called 'snap rolls'
in the USA) are initiated by rapid pitch and yaw control inputs,
causing one wing to partially stall whilst the other still flies
- leading to instantaneous high acceleration in roll. This
abrupt high energy translation makes the manoeuvre hard to study
and hence difficult to judge accurately. |
Criteria: |
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At the entry to the
manoeuvre the aircraft MUST - |
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abruptly pitch positive or
negative to briefly set the wings at a critical angle and cause
an immediate semi-stalled condition. |
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yaw to unbalance the airflow between the wings, and so reduce the critical angle of one wing
whilst increasing the other. |
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The initial 'nod' and
yaw (can be together or made as a quick "one-two") must
immediately produce rapid "auto-rotation". |
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"Auto-rotation"
means that one wing has a higher angle of incidence than the
other, is in a stalled condition and thus causing high drag,
whilst the other wing has a lower angle of incidence, is not
stalled and is still providing lift. In true auto-rotation NO
aileron is be required to initiate and drive the rolling motion
- if you see in-flick aileron applied you might believe
that the aeroplane is not really flicking. |
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Throughout the
flick-roll the aeroplane must remain auto-rotating by continued
application of the initiating pitch and yaw control inputs. A
translation to aileron rolling at any stage before the required
angle of rotation has been completed would mean that the flick
has ended early - a certain 1 point/5° downgrade. |
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At the correct angle
of rotation the roll should cease abruptly, and the aircraft
should continue along an axis closely parallel to the extended
pre-roll axis. This stoppage must primarily be driven by
reduction in the pitch angle and removal of the yaw to un-stall
the wings and restore balanced flight, so once again any aileron
applied to stop the roll is not the appropriate control. |
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Check carefully that
the last part of the auto-rotation is not turned into an aileron
roll to assist accurate end-stop positioning, a commonly adopted
ploy that must be penalised. |
Downgrades:
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Flick-rolls happen so rapidly
that it is your subjective 'perception' as to whether the two
essential components - pitch and yaw - have been successfully
applied to cause auto-rotation, and removed at the right moment
to stop it. It is not possible to test the presence/absence of
these ingredients from a video, so if you believe they were
absent you must use the Perception Zero (PZ) rather than the
Hard Zero (HZ). |
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If the stall is inadequate the
aircraft will fly a 'barrelled' roll with both wings providing
lift, and considerable sideways translation from the starting
axis is likely - this MUST be given a Perception Zero mark. |
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Don't forget also to check that
the manoeuvre you see is positive or negative - whichever one
the sequence calls for. If it goes the 'wrong way' it must get a
Hard Zero. |
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Aircraft characteristics vary a
lot in their requirements for flick initiation, and with some
modern types the pitch movement can be quite small. For a given
change in pitch angle the tail will probably move further than
the nose, so look for a tail movement towards the wheels for a
positive flick (as in the diagram above of a one-turn positive
flick in level erect flight) and away from the wheels for a
negative figure. |
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If you see a 'flick' that in your
opinion is not primarily driven by pitch & yaw or where aileron
input is an obvious factor in driving the roll, then you should
give it a Perception Zero. |
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In every other important aspect
the penalty to apply is the usual 1 point per 5° of inaccuracy
observed. |