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eventualities should the rotor become too severe, are
among topics that are best discussed on the ground
prior to flight.
After all preparations are complete, it is time to get in
the glider. Some pilots may be using a parachute for the
first time on wave flights, so make sure you are familiar
with its proper fitting and use. The parachute fits on
top of clothing that is much bulkier than for normal
soaring, so the cockpit can suddenly seem quite
cramped. It will take several minutes to get settled and
organized. Make sure radio and oxygen are easily
accessible. If possible, the oxygen mask should be in
place, since the climb in the wave can be very rapid. At
the very least, the mask should be set up so that it is
ready for use in a few seconds. All other gear (e.g., mittens,
microphone, maps, barograph, etc.) should be
securely stowed in anticipation of the rotor. Check for
full, free rudder movement, since footwear is likely
larger than what you normally use. In addition, given
the bulky cold-weather clothing, check to make sure
the canopy clearance is adequate. The pilot’s head has
broken canopies in rotor turbulence so seat and shoulder
belts should be tightly secured. This may be difficult
to achieve with the extra clothing and accessories,
but take the time to make sure everything is secure.
There will not be time to attend to such matters once
the rotor is encountered.
GETTING INTO THE WAVE
There are two possibilities for getting into the wave:
soaring into it or being towed directly into it. Three
main wave entries while soaring are: thermalling into
the wave, climbing the rotor, and transitioning into the
wave from slope soaring.
At times, an unstable layer at levels below the mountaintop
is capped by a strong, stable layer. If other conditions
are favorable, the overlying stable layer may
support lee waves. On these days, it is sometimes possible
to largely avoid the rotor and thermal into the
wave. Whether lee waves are suspected or not, near the
thermal top the air may become turbulent. At this point,
attempt a penetration upwind into smooth wave lift. A
line of cumulus downwind of and aligned parallel to
the ridge or mountain range is a clue that waves may be
present. [Figure 10-20]
Another possibility is to tow into the upside of the
rotor, then climb the rotor into the wave. This can be
rough, difficult, and prone to failure. The technique is
to find a part of the rotor that is going up and try to stay
in it. The rotor lift is usually stationary over the ground.
Either “figure-8” in the rotor lift to avoid drifting
downwind, fly several circles with an occasional
straight leg, or fly straight into the wind for several seconds
until lift diminishes. Then circle to reposition in
the lift. Which choice works depends on the size of the
lift and the wind strength. Since rotors have rapidly
changing regions of very turbulent lift and sink, simple
airspeed and bank angle control can become difficult.
This wave-entry technique is not for new pilots.
Depending on the topography near the soaring site, it
may be possible to transition from slope lift into a lee
wave that is created by upwind topography as shown in
Figure 9-27. In this case, climb as high as possible in
slope lift, then penetrate upwind into the lee wave.
When the lee waves are in phase with the topography,
it is often possible to climb from slope to wave lift
without the rotor. At times, the glider pilot may not
realize wave has been encountered until they find lift
steadily increasing as they climb from the ridge.
Climbing in slope lift and then turning downwind to
encounter possible lee waves produced downwind of
Figure 10-20. Thermalling into wave.
10-14
the ridge is generally not recommended. Even with a
tailwind, the lee-side sink can put the glider on the
ground before the wave is contacted.
Towing into the wave can be accomplished by either
towing ahead of the rotor or through the rotor. Avoiding
the rotor completely will generally increase the towpilot’s
willingness to perform future wave tows. If possible,
tow around the rotor and then directly into the
wave lift. This may be feasible if the soaring site is
located near one end of the wave-producing ridge or
mountain range. A detour around the rotor may require
more time on tow, but it’s well worth the diversion.
[Figure 10-21]
Often, a detour around the rotor is not possible and a
tow directly through the rotor is the only route to the
wave. The rotor turbulence is, on rare occasion, only
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Glider Flying Handbook(144)
