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 .


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.

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.


A scratched birdie is good enough for the stabilizer at no cost.
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)
 Get a T connector and fix it on the pendulum rod.


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.



Double  birdie stabilizer

With heavier rigs, let's try two birdies set as a V downwind, forming a 30° angle.


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.
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

 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.


The KAP Feather is really effective over 5 m/s wind.