Dangerous situations and extreme flying
Section 7
33
may
shoot
forwards
and
suffer
an
asymmetric collapse. If the pilot suspects
that the glider has unintentionally been put
into a spin, the brake which has been pulled
down too far must be released immediately.
WARNING
If the spin does not stop, check whether
you have released the brakes fully!
Emergency steering
If for some reason the brake lines are not
working, e.g. if the knot on the brake handle
has come undone or a brake line is
defective, the APUS RS can also be steered
and landed using the rear risers.
In this case, stall happens more quickly and
the pilot must compensate for the changed
flight behaviour by pulling carefully on the
risers.
Other tips for dangerous
situations
Stalling in rain
In general, there are two reasons why a
paraglider may go into deep stall in rain:
1. The first risk lies in the fact that the
canopy weight increases if a glider is flown
in rain for any length of time. The centre of
gravity and angle of attack then shift, which
can result in airflow separation/stall. It is
relevant here that if a glider absorbs more
water (as older gliders do because they lose
their water-repellent coating over time) and
is closer to the deep stall limit because of its
design and age, less water absorption and
thus weight increase will put the glider into
deep stall.
2. When there is rain, there can be so many
water droplets on the top surface of a glider
that almost the entire upper surface is
affected but, even so, the drops
“bead” so
the surface is not wet through. This makes
the top surface so
“rough” in texture from
the drop formation that the airflow over the
top of the wing separates from the surface.
This phenomenon has been known for
some time from hang-gliding and gliding.
With new gliders, the droplets are absorbed
less quickly by the fabric. Thus, the newer a
glider is, the greater the number of droplets
caught on the top surface and the bigger
those droplets are, the greater the risk that
there could be airflow separation. We were
able to recreate these conditions by
practical tests and computer simulations,
but they occur very rarely.
It is the case in both of the above situations
that the control travel and braking distance
first reduce and then the deep stall is
caused, mostly by alteration of the brake
travel or angle of attack, e.g. by a gust or
thermal.
WARNING
Flying in extremely humid weather or in
rain is outside of the operating limits of
the glider. If you are not able to avoid
flying in rain, please observe the
following:
it is advisable to fly with slight
acceleration during and after the rain
(min. 30% or more)
use no brake input or as little as
possible
do not use big ears
control travel reduces
avoid tight turns, especially in the final
approach. If conditions allow, you
should also fly slightly accelerated in
this phase
avoid large angles of attack and the
possible early stall near the ground
(release the speed bar only slowly)
