Foreword
When I started to wish to stabilize
my simple pendulums, I imitated the regulating systems used
in clocks to slow some movements of ring mechanisms.
I tried some devices like wind
vanes, without satisfaction. The bottle-stabilizer
has been one alternative that I left quite soon after because
needing more efficiency for my Konica Hexar weighting 480g.
Consequently, the wind shift was becoming too important..
The KAP Feather has been
tried but its action found not enough .
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Then, with the lightest digital
camera which has in-built intervalometer, and set on the
cradle " Goldcrest",
I found out that too many pictures have to be deleted. The
pendulum has no stabilization and the camera triggered at
any time. Used to release by radio transmitter, I know that
shooting when the cradle is stable is giving better results. So, for auto-kap and light rig,
I made a new plastic bottle stabilizer and tried again the
KAP Feather!
Since 2013 a new device provides
all satisfaction: low cost, efficient, léger, easy
to make and to store, this is the shuttlecock stabiliser.
To me it has more pros and is my favourite accessory on
the Filalu
pendulum rig.
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Shuttlecock
stabilizer
- Is it necessary to describe a badmington shuttlecock
also called birdie? Only two features need to be mentioned:
- - the weight is less than 5.5 grams
- - an extraordinary aerodynamic behaviour.
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- A scratched birdie is good enough for the stabilizer
at no cost.
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- The making is simple.
- - Drill a Ø2 mm hole in the cork
- - Push through a Ø3 mm carbon rod
15 cm long as a arm.
- - Add a stopper on the rod behind the cork.
- (use flexible plastic tube which internal diameter is
much smaller than the diameter of the rod)
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- Get a T connector and fix it on the pendulum rod.
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Moment arm
- The length of the rod is the main feature that have
to be defined. Because this dimension will act considerably
on the moment arm, it makes all the trick for the efficiency
on any of the stabilizers but is more important on the birdie.
- The longer the arm, the higher is the moment arm.
When the arm is too short, the span movement can't be dampened
enough. When too long it forces the rig to a slight rotation
each times the rig is moving aside due to a lateral move of
the kite.
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Double birdie stabilizer
With heavier rigs, let's try two birdies set as a V downwind,
forming a 30° angle.
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Bottle-stabiliser
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Built a tube-funnel cost nothing,
takes only few time, and is easily set. It is also an efficient
unit to stabilize the pendulum. It works also on a Picavet
suspension.
The cylindrical part is necessary
to dampen the roll..The wind shift is Low and acceptable. Upset
slightly the horizon angle of the camera to compensate the
shift in strong winds.
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How to make it:
Take a light plastic bottle, diameter
8cm as minimum, and cut out the neck part with at least
10cm of the cylindrical part. This stabilizer weights less
than 15g.
This is the simple mounting on
the Goldcrest cradle:
At the edge of the cap, hollow
through Ø3mm; look at through inside to center holes
in the neck. Withdraw the cap, and now enlarge the holes
to Ø 6mm. Slip on the neck part on the pendulum rod,
and screw the cap for tightening.
Set the tube-funnel the lowest
when wind is light, and set it slightly upper when wind
is stronger.
It is not as efficient as the stabilizer
bow and the Haugrund's damping device. From my experiments,
it starts to be effective against roll over 4 m/s winds.
Increase the efficiency by
making a few ears
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The
KAP Feather alternative:
A plug & play alternative is the setting
of the Jones Airfoil's KAP Feather. I recommend the 25cm
square model.
Forget the holding bar which is provided
with a threaded rod Ø 4mm weighting 25g by itself. Keep
the plastic tee Excel Ø6-Ø3 and slip it on the
pendulum rod. This is weighting 15g.
Do not forget to upset the horizon
angle of the camera to compensate the wind shift which is
easily important with strong winds. And to counteract the
wind shift, it is also possible to have a shifted-pendulum
as the " Sparrow"
Have also spare plastic pipe for
the flexible connectors, because there is nothing more annoying
than to find one broken at the very moment to use it.
Make secure also the back clip
with additional stopper on the boom, because some strong
wind blows could succeed to shift it away.
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The KAP Feather is really effective
over 5 m/s wind.
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