Advance acoustic PI BI, User Manual

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Deep stall
The PI BI cannot go into stable parachutal stall by itself . The wing can
be brought to the point of parachutal stall, however, by means of the
brakes, and can stay there (see chapter “Flying with a Wet Glider”) .
Caution: If you are flying tight, slow airspeed circles in signifi-
cant turbulence you may stall unexpectedly . If this happens let
both brakes go immediately .
Landing
Notably good flare behaviour and precise handling make for very easy
PI BI landings . Residual energy trades well for height, allowing you and
your passenger to make a gentle touchdown .
Always fly a proper landing circuit with a defined final approach, with-
out rolling and pitching . From a final approach to the ground at trim
speed apply the PI BI brakes continuously, finally going through to full
brake . By making this kind of “fully flared” landing the speed can be
brought to a minimum, and the passenger sets down softly .
Caution: Steep turn reversals lead to strong swinging of the pi-
lot and passenger, and should not be done near the ground
Caution: Braking will reduce your speed and increase your sink
rate, but it will certainly seriously restrict your ability to manoeuvre .
Caution: Getting below minimum speed leads to stalling: this
should unquestionably be avoided when top landing, and on
final approach .
Handle with care: Never let your glider fall to the ground on its
leading edge . The overpressure so caused inside the wing can
rip the cell walls and damage the leading edge . The material can
be damaged by the friction .
Handle with care: After landing in water the canopy can quick-
ly fill up, and become very heavy . The canopy should be lifted
out of the water by its trailing edge, giving the water a chance to
run out . Otherwise it might tear under this unaccustomed heavy
load .
Flying with a wet paraglider
Flying with a wet glider creates a risk of deep stall . Deep stall is often
the result of a combination of factors . The weight of the wet canopy
goes up, and this increased weight increases the angle of attack,
which always puts the glider nearer the deep stall limit . Added to this,
water drops on the top surface have a detrimental effect on the laminar
flow of the boundary layer near the leading edge, which distinctly re-
duces the maximum lift coefficient . If the wet glider is also being flown
at its lower weight limit there is a further small effect of an increased
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