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FW6.2 Building Instruction October 2015
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19
11. Tuning and tips
11.1 Flying weight and centering the masses
Our long experience has shown that the
take-off weight
and
centering of the masses
are the most important factors to
optimize the starting height
.
The model should be light.
The mass of the model should be well centered.
A lower mass can be accelerated to a higher top speed during
the discus rotation. The higher top speed, in turn, has a
significantly higher impact on the resulting kinetic energy than
the mass of the airplane. To be precise a square. Ekin = m * v²
Due to the good mass centering the oscillation of the model
after release is reduced. This means, the better the centering of
masses is, the less it slows down.
The centering of masses is also improved by loading more
ballast. This increases the flying weight, but everyone should try
out, what is his personal optimum. Every pilot has his own
optimal weight of glider, which he can accelerate best.
In addition, the amount of ballast depends of course on the
strength of wind and thermals. The Zone V2 can tolerate ballast
very good, and you should not fly with too little weight at higher
wind speeds.
As you can see, there is still plenty of room to optimize.
To put it into numbers,
Mark Drela
has developed a method to
measure the yaw of gyration
. This defines how good or bad a
glider has centred its masses:
Hang your model upside down on two 1,5m long threads, which
you fix 30mm from the centre of gravity. Now move the glider
for 45° and the let it swing. Take the time of 5 swings. Repeat
this process several times to get an average value.
The faster the model swings, the faster it will stabilize after the
launch and the higher it will start.
11.2 Flightpath during start
You could reach more starting height when you
adjust the
flightpath to the wind strength
. When the wind is weak you
should start very steep into the sky. And when the wind is
strong the flightpath should be much more flat.
Always
TEST THE RECEPTION
on ground before you fly!
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