Practice flying directly into the wind (upwind of
yourself) without letting the plane get off course, and
then turn and come downwind until the plane is even
with you and try it again. When you are comfortable
with flying directly into the wind, start letting the plane
go behind you (downwind) a little before you start back
upwind. Continue this until you can fly directly towards
you from downwind without getting disoriented. At this
point you can start to establish a “landing pattern” and
bring the sailplane in for a landing from downwind.
Always land into the wind.
This enables the plane to be
flown as slowly (ground speed) as possible for accurate
and damage free landings.
It is probably not a good idea to try and fly around at a
low altitude with the motor on during your first flights.
This will cause the airplane’s speed to increase and
make the controls more responsive which is just what a
beginner does not need.
The Upstar ARF will climb to altitude several times on a
single charge allowing you to have flights well over ten
minutes without finding any “lift”. You should be able to
get two full climbs above 500’ on a single charge
although there are many factors that figure into this.
Thermal soaring is one of the most intriguing of all
aspects of flying and the Upstar ARF was designed to
excel at thermal soaring even in the hands of a novice.
It can be hard for the average person to understand how
a plane can fly for a long time and gain altitude
without
a motor!
Thermals are a natural phenomenon that happen
outside, by the millions, every single day of the year.
Thermals are responsible for many things including
forming several types of clouds, creating breezes, and
distributing plant seeds and pollen. If you have ever
seen a dust devil (which is nothing more than a thermal
that has picked up some dust), you have seen a thermal
in action. Their swirling action is very similar to that of
a tornado but of course much gentler. Most thermals
have updrafts rising in the 200 – 700 feet per minute
range but they have been known to produce updrafts of
over 5,000 feet per minute (that’s over 50 miles/hour
straight up!) These strong thermals can rip a plane apart
or carry the plane out of sight before the pilot can get
out of the updraft.
Thermals are formed by the uneven heating of the earth and
buildings, etc. by the sun. The darker colored surfaces
absorb heat faster than the lighter colors which reflect a
great deal of the sun’s energy back into space. These darker
areas (plowed fields, asphalt parking lots, tar roofs, etc.) get
warmer than the lighter areas (lakes, grassy fields, forests,
etc.). This causes the air above the darker areas to be
warmer than the air over the lighter areas and the more
buoyant warm air rises as the cooler, denser air forces its
way underneath the warmer air. As this warm air is forced
upward it contacts the cooler air of the higher altitudes and
this larger temperature difference makes the thermal rise
quicker. The thermal is gradually cooled by the surrounding
cooler air and its strength diminishes. Eventually the
thermal stops rising and any moisture contained in the once
warm air condenses and forms a puffy cumulus cloud.
These clouds, which mark the tops of thermals, are usually
between 2000 and 5000 feet high.
It takes a lot of concentration to thermal soar effectively. An
electric sailplane can fly along the edge of a thermal and
unless the pilot is carefully watching the model he may not
realize the opportunity to gain some altitude. Because most
thermals are relatively small (a couple hundred feet in
diameter or less at 400’ altitude) compared to the rest of the
sky, the sailplanes will rarely fly directly into the thermal
and start rising. Generally, the electric sailplane will fly into
the edge or near a thermal and the effects the thermal has
on the plane may be almost unnoticeable. As the electric
sailplane approaches a thermal, the wing tip that reaches
the rising air first will be lifted before the opposite wing tip.
This causes the plane to “bank” and turn away from where
we would like the plane to go.
When you are thermal soaring, try to fly as smoothly and
straight as possible. Trim the plane to fly in a straight line and
only touch the controls when you have to. Watch the electric
sailplane carefully and it will tell you what it is encountering.
When the electric sailplane flies directly into a thermal it will
either start rising or stop sinking. Either case is reason enough
to start circling (especially in a contest where every second
counts). Fly straight ahead until you feel like you are in the
strongest lift, fly a couple of seconds farther (so your circle
will be centered in the strongest lift) and then start circling in
a fairly tight but smooth turn. When the electric sailplane is
low the turns have to be tighter to stay in the strongest lift. As
the plane gains altitude, the turns can be larger and flatter.
The flatter the turn, the more efficient the plane is flying, but
don’t be afraid to really “crank” it into a steep bank when
THERMAL SOARING
FACTS ABOUT THERMALS
THERMAL FLYING
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