Multiplex RR EasyGlider, Инструкция по эксплуатации, Страница: 15 / 48

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the “model” end of the line Fig. 17 . The ring is engaged on the
towhook, the towline unwound and your assistant (launcher)
takes the free end and walks upwind until the line is taut. The
model should be held under gentle tension before it is released.
The launcher watches the model (over his shoulder), adjusting
his pace to maintain a steady rate of climb. Take care not to
overstress the model during the launch; this is a particular danger
in a fairly strong wind.
Bungee launching
This is the easiest method of launching a glider of this size, as
no assistant is needed, and launch heights of around 100 m are
easily achieved. From this altitude quite long flying times can be
achieved, and they will be even longer if you manage to contact
a thermal, although this does depend on the prevailing weather.
Thermal flying
Making the best use of flat field thermals is not particularly easy,
and calls for considerable skill and experience. Areas of rising
air are harder to detect and recognise at a flat field, because they
tend to occur at higher altitude than at the hillside, where it is
often possible to find lift while the model is cruising along the
edge of the slope and then circle away in it. A thermal at a flat field
which occurs directly overhead is very hard to recognise, and to
exploit it to the full requires a highly skilled pilot. For this reason
it is always best to go thermal seeking off to one side of where
you are standing.
You will recognise thermal contact by the glider’s behaviour. Good
thermals are obvious because the model will climb strongly, but
weak thermals take a practised eye to detect, and you will need
a lot of skill to make use of them. With a little practice you will be
able to recognise likely trigger points for thermals in the local
landscape. The ground warms up in the sun’s heat, but heat
absorption varies according to the type of terrain and the angle
of the sun’s rays. The air over the warmer ground becomes
warmer in turn, and the mass of warm air flows along close to
the ground, driven by the breeze. Strong winds usually prevent
thermal build-up. Any obstruction - a shrub or tree, a fence, the
edge of a wood, a hill, a passing car, even your own model on
the landing approach - may cause this warm air to leave the
ground and rise. Imagine a drop of water on the ceiling,
wandering around aimlessly, and initially staying stuck to the
ceiling. If it strikes an obstruction it will fall on your head. A triggered
thermal can be thought of as the opposite of the drop of water.
The most obvious thermal triggers include sharply defined snow
fields on mountain slopes. The air above the snow field is cooled,
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
Fig. 18 . 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: