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:
At the entry to the
manoeuvre the aircraft MUST -
~
abruptly pitch positive or
negative to briefly set the wings at a critical angle to cause
an immediate semi-stalled condition
~
yaw to unbalance the airflow between the wings, and so reduce the critical angle of one wing
whilst increasing the other.
The initial 'nod' and
yaw (can be together or made as a quick "one-two") must
immediately produce rapid auto-rotation.
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.
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.
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:
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 (soft) zero mark.
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.
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.
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 SOFT zero (this is a matter of perception).
In every other important aspect
the penalty to apply is the usual 1 point per 5° of inaccuracy
observed.
