Dangerous situations and extreme flying
Section 7
31
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)
Advertising and adhesives
Always make sure before attaching
advertising to the glider that the adhesive
planned will not alter the glider’s flight
behaviour. If you are in doubt, we
recommend that you do not attach the
adhesive.
IMPORTANT
Attaching adhesives to the glider which
are large, heavy, or made of unsuitable
material may result in revocation of the
certification.
Overloading
The glider structure is put under high levels
of strain in particular on extreme flight
manoeuvres, rapid descent methods (spiral
dives) or prohibited aerobatic manoeuvres.
They considerably accelerate the aging
process of the structure and should
therefore be avoided.
The glider must be inspected earlier than is
usually the case if it has been put under
more than the usual degree of strain.
