3rd Year Special Annual Double Issue Vol 4 Issue 1 & 2 Jan - Apr 2 3rd Year Special Annual Double Issue Vol 4 Issue | Page 24

ground. When the pilot reaches
his desired height, he ends this
maneuver by slowly releasing the
inner brake, shifting his weight to
the outer side and braking on this
side. The release of the inner brake
has to be handled carefully to end
the spiral dive gently in a few turns.
If done too fast, the wing translates
the turning into a dangerous
upward and pendular motion.
Spiral dives put a strong G-force
on the wing and glider and must
be done carefully and skilfully.
The G-forces involved can induce
blackouts, and the rotation can
produce disorientation. Some high-
end gliders have what is called
a “stable spiral problem”. After
inducing a spiral and without
further pilot input, some wings do
not automatically return to normal
flight and stay inside their spiral.
Serious injury and fatal accidents
did occur when pilots could not exit
this maneuver and spiraled into the
ground.
The rate of rotation in a spiral dive
can be reduced by using a drogue
chute, deployed just before the
spiral is induced. This reduces the G
forces experienced.
Soaring
Soaring flight is achieved by utilizing
wind directed upwards by a fixed
object such as a dune or ridge. In
slope soaring, pilots fly along the
length of a slope feature in the
landscape, relying on the lift
provided by the air, which is forced
up as it passes over the slope.
Slope soaring is highly dependent
on a steady wind within a defined
range (the suitable range depends
on the performance of the wing
and the skill of the pilot). Too little
wind, and insufficient lift is
available to stay airborne (pilots
end up scratching along the slope).
With more wind, gliders can fly well
above and forward of the slope, but
too much wind, and there is a risk
of being blown back over the slope.
A particular form of ridge soaring
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is “condo soaring”, where pilots
soar a row of buildings that form an
artificial “ridge”. This form of
soaring is particularly used in flat
lands where there are no natural
ridges, but there are plenty of man-
made, building “ridges”.
Thermal flying
When the sun warms the ground,
it will warm some features more
than others (such as rock faces or
large buildings), and these set off
thermals which rise through the air.
Sometimes these may be a simple
rising column of air; more often,
they are blown sideways in the wind
and will break off from the source,
with a new thermal forming later.
Once a pilot finds a thermal, he
begins to fly in a circle, trying to
center the circle on the strongest
part of the thermal (the “core”),
where the air is rising the fastest.
Most pilots use a vario-altimeter
(“vario”), which indicates climb rate
with beeps and/or a visual display,
to help core in on a thermal.
Often there is strong sink
surrounding thermals, and there
is also strong turbulence resulting
in wing collapses as a pilot tries
to enter a strong thermal. Good
thermal flying is a skill that takes
time to learn, but a good pilot can
often core a thermal all the way to
cloud base.
Cross-country flying
Once the skills of using thermals to
gain altitude have been mastered,
pilots can glide from one thermal to
the next to go cross country. Having
gained altitude in a thermal, a pilot
glides down to the next available
thermal.
Potential thermals can be identified
by land features that typically
generate thermals or by cumulus
clouds, which mark the top of a
rising column of warm, humid air
as it reaches the dew pointand
condenses to form a cloud.
Vol 4 | Issue 1 |Jan - Feb 2019