21
Flight on a flat-field site
Flying on a flat-field site is relatively safe – without the risk of sinking which you may
experience when flying at a slope site.
It takes an experienced model pilot to be able to exploit thermal lift. Due to the higher
altitudes strong lift areas are harder to recognise by observing the flight
characteristics of the model on a flat-field site than at a slope site, where "beards"
can be found at eye level. Only the most skilled pilots are able to recognise a strong
lift area on a flat-field site directly "overhead" and fly it; therefore always and look for
it at a transve distance from your position.
The flight characteristics of your model allow you to recognise a strong lift areas. If
the thermal is good a strong climb is recognisable, weak lift areas require a trained
eye and a skilled pilot. After some practice you will be able to recognise the trigger
points for the thermals. The air warms up - depending on the reflective power of the
ground more or less strongly - and air flows driven by the wind closely above the
ground. The roughness of the terrain, a shrub, a tree, a fence, a forest edge, a hill, a
passing car, even on your landing model aircraft may cause warm air to lifted from
the ground and rise upwards. A fitting comparison in the reverse sense is the
travelling water drop on the ceiling which initially remains stuck to the ceiling, pushes
against some roughness and then falls down.
The most distinctive thermal triggers are sharply defined snow fields on mountain
slopes. Above the snow field the air is cooled down and flows downwards, on the
downhill side of the snowfield edge this meets the warm air flowing slopeside up and
replaces it abruptly. This results in strong climbs, but at the same time rough thermal
bubbles. The rising warm air is to be detected and "centred". When doing so the
model should by control corrections be kept in the centre of the lift area as the
strongest climb values are to be expected there. However, this requires some
practice.
Leave the climbing zone at the right time in order to avoid visibilty difficulties.
Remember that the model can be seen better under clouds than in the blue,
cloudfree areas. If height must be reduced consider the following:
The stability of the Alpina 3001 Champ
is quite high, but there are limits.
High speed
flights
in the F3B-manner
should
only be attempted if the flaps are in neutral
position!
A GRP-coating extends the speed range and the application possibilities of
the model.
Start the landing at a relatively high altitude and overcome the dangerous zone at low
altitude quickly and safely using the airbreaks/flaps. A correctly flown landing
approach – consisting of a parallel flight with the wind away from the pilot, a traversal
flight and a straight, butterfly-supported landing approach with subsequent catch for
landing – ensures the safety of the model, pilot and spectators.
