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and flows downhill; at the edge of the snow field, part-way down
the valley, the cool air meets warm air flowing gently uphill, and
pushes it up and away as if cut off by a knife. The result is an
extremely powerful but bumpy thermal bubble. Your task is to
locate the rising warm air and centre your model in it. You will
need to control the glider constantly to keep it centred, as you
can expect the most rapid climb rate in the core of the thermal.
Once again, this technique does demand some skill.
To avoid losing sight of the machine be sure to leave the thermal
in good time. Remember that a glider is always easier to see
under a cloud than against a clear blue sky. If you have to lose
height in a hurry, do bear the following in mind:
The structural strength of the EasyGlider / EasyGlider Electric is
very great for this class of model, but it is not infinite. If you attempt
to destroy the model forcibly, please don’t expect any sympathy
or compensation from us.
Flying at the slope
Ridge soaring is an extremely attractive form of model flying.
Soaring for hours on end in slope lift, without needing any outside
aid for launching, must be one of the finest of modelling
experiences. But to “milk” a thermal to the limits of vision, bring
it down again in a continuous series of aerobatic manoeuvres,
and then repeat the whole show - that must surely be the last
word in model flying.
But take care - there are dangers for your model lurking at the
slope. Firstly, in most cases landing is much more difficult than
at a flat field site. It is usually necessary to land in the lee of the
hill where the air is turbulent; this calls for concentration and a
high-speed approach with last-minute airbrake extension. A
landing on the slope face, i.e. right in the slope lift, is even more
difficult. Here the trick is to approach slightly downwind, up the
slope, and flare at exactly the right moment, just before touch-
down.
Aero-towing
An ideal combination for learning to aero-tow, and for actual
aero-towing, is a Magister and an EasyGlider. If you wish to take-
off from grass, you will need a fairly powerful motor in the Magi-
ster, e.g. a brushless external rotor type (generally known as an
“outrunner”) with around 300 Watts of power.
For the tow you require a 20 m length of braided cable of 1 to 1.5
mm Ø. Cut a hole in a piece of hook-and-loop tape and tie it to
the end of the towline. Glue the matching piece of hook-and-
loop tape directly to the underside of the nose of the EasyGlider.
Form a loop in the other end of the towline (at the tug), and
connect it to the aero-tow coupling. Assemble the models and
set them up directly into wind, the glider behind the tug. Check
that the towline is resting on top of the Magister’s tailplane. The
tug now rolls forward until the towline is taut, and only then should
the tug’s pilot apply full-throttle. Both aeroplanes accelerate: the
tug stays on the ground initially, while the glider lifts off, but the
glider pilot keeps his model flying low above the ground, directly
in the wake of the tug; the tug can now lift off safely. The two
models should be kept climbing steadily, even through turns.
Avoid flying directly over your heads during the first few attempts
at aero-towing, as it is difficult to detect the models’ attitudes
from this angle. To drop the tow, bank the glider over into a tight
turn and apply full up-elevator; the hook-and-loop tape will now
let go, and the glider is “free”.
Electric flying
With the electric version - the EasyGlider Electric - you have the
optimum level of autonomy and independence. You can fly from
a flat field and carry out about four climbs to a sensible gliding
height from a single battery charge. At the slope you can also
keep the electric power system as a “lifebelt”, i.e. you only use
the motor to “keep afloat”, and avoid landing out, i.e. landing at
the bottom of the slope when the lift fails.
Flight performance
What is meant by a glider’s performance?
The two most important parameters are sinking speed and glide
angle. Sinking speed is a measure of the vertical height lost per
second relative to the surrounding air. The sinking speed is
primarily determined by the wing loading (weight relative to wing
area). Here the EasyGlider offers a really excellent performance
- much better than conventional models - as its wing loading is
so low (only around 17 g / dm²). This means that only slight
thermal assistance is necessary (warm air rising) to cause the
model to gain height. Wing loading is also the main factor in
determining the model’s airspeed - the lower the loading, the
slower the model. Low airspeed means that the model can be
turned extremely tightly, and this is also advantageous when
thermal flying, as areas of lift are usually very small when close
to the ground.
The glider’s low airspeed also benefits you considerably if you
are a beginner, as you have more time to think, and the model is
more likely to “excuse” a mistake at the controls.
However, there’s always a down-side:
The other important parameter in glider performance is the glide
angle. This is stated as a ratio, i.e. from a particular altitude the
model flies such and such a distance. The glide angle increases
as wing loading rises, and at the same time - of course - the
model’s airspeed increases. This becomes necessary if you
wish to fly in relatively strong winds, and when you need “energy
retention” for flying aerobatics.
For thermal flying you need a good glide angle too, as this is the
key to flying across areas of “sink” (the opposite of a thermal)
quickly, so that you can seek out another thermal. To increase
the glide angle you need to increase the wing loading, and this
is done by increasing the glider’s weight, i.e. by installing ballast
in the model. This should be positioned in the wing if possible.
In the EasyGlider there is an ideal location: it is the GRP tube
which forms the wing joiner. The internal diameter of this tube is
7.8 mm. Normally a ballast rod of this size would be difficult to
find, and expensive to purchase. However, by chance the diameter
of standard M8 studding (threaded rod) is just the right size. This
material has a diameter of 7.7 mm, and you will be able to buy
it at low cost in any DIY store. You may find that only half a full
length is sufficient. In this case you must ensure that the rod
cannot slide from side to side, e.g. by fitting lengths of balsa
dowel in both ends of the wing joiner, so that the weight is held
in the centre.
Safety
Safety is the First Commandment when flying any model aircraft.
Third party insurance should be considered a basic essential. If
you join a model club suitable cover will usually be available
through the organisation. It is your personal responsibility to
ensure that your insurance is adequate.
Make it your job to keep your models and your radio control
system in perfect order at all times. Check the correct charging
procedure for the batteries used in your RC set. Make use of all
sensible safety measures and precautions which are advised
for your system. An excellent source of practical accessories is
the MULTIPLEX main catalogue, as our products are designed
and manufactured exclusively by practising modellers for other
practising modellers.
Always fly with a responsible attitude. You may think that flying
low over other people’s heads is proof of your piloting skill; others
know better. The real expert does not need to prove himself in
such childish ways. Let other pilots know that this is what you
think too. Always fly in such a way that you do not endanger
yourself or others. Bear in mind that even the best RC system in
the world is subject to outside interference. No matter how many
years of accident-free flying you have under your belt, you have
no idea what will happen in the next minute.