The next Open Call is Tuesday, October 12, at 2pm Central Time. Click here for call-in details!

Public Lab Research note


Pendulum or Picavet for Kites. Why?

by pdhixenbaugh | September 12, 2020 19:39 12 Sep 19:39 | #24567 | #24567

Hi @cfastie! Apologies if this has been answered elsewhere, but as I've been searching I haven't found an explicit answer.

What about the pendulum and the picavet makes the picavet better for Kite photography? According to what I can find, the pendulum works better for vertical lines, like with a balloon on a calm day. Does the picavet handle the erratic motion of the kite line better, and provide better stability than a pendulum would?

I would like to try the jerkpan on the aerobee with a kite, and it looks like if I could only buy one, I would get the pendulum. What do you think?


2 Comments

Hi Patrick,

Sorry for the delay, my Public Lab notifications go to a folder that I rarely see.

You are correct that a Picavet does not work well when the flying line is vertical. The camera rig just hangs against the flying line or bumps against it and gets knocked around. A pendulum can hold the camera rig away from the flying line, especially if it has a stiff wire to wrap the line around and if that wire is connected solidly to a firmly flexible piece of tubing.

Kite lines are almost never vertical but balloon lines can be vertical or close to it. If there are a few mph of steady wind, the balloon will pull downwind and the line will be angled enough for a Picavet to work fine.

There are three clever things about the Picavet. One is that it keeps the camera rig level regardless of the angle of the flying line. This is accomplished by allowing the Picavet line to slide through the connections so the weight of the camera rig keeps it hanging in the same position. The second thing is that a Picavet provides two points of attachment with the flying line and that adds stability (damps swinging along the axis of the flying line). The third thing is that the Picavet cross extends perpendicular to the axis of the flying line and adds some stability in that direction.

The only thing that keeps a KAPtery pendulum from swinging is the stiff attachment wire and the flexible tubing at the top of the shaft. If that system is stiff enough where it should be and flexible enough where it should be, the camera rig can have a fairly smooth ride.

The Picavet seems to be more popular than the pendulum with KAP people. That might be partly because the Picavet is an elegant solution and using one without tangling the lines is a rite of passage. Many KAPers use pendulums and swear by them (while others get the Picavet lines tangled and swear at them).

You can buy an Aerobee Rig at the KAPtery without a suspension (but you need a way to attach it to the flying line). The Aerobee Rig works with either a Picavet or a pendulum. But an important advantage of the Aerobee Rig is that it is designed to work with the JerkPan. The JerkPan sort of works with a Picavet, but works much better with a pendulum. That's because the sliding Picavet lines absorb lots of the motion of the flying line. So jerking the line does not send much of a jerk to the camera rig under a Picavet. A pendulum with a weighty camera at its end will whip a little bit when the flying line is jerked so the escapement will ratchet and pan the camera rig.

I hope this helps,
Chris

Yes, it does! It sounds like a Picavet may not work well with a balloon, but a good Pendulum can work with a balloon or a (fairly stable) kite.

These public lab messages go to a different folder in my email too -- I didn't see this until I logged in. So no worries. :)

Thanks, Patrick


Reply to this comment...


Login to comment.