Introduction:
After some remarks from prof. René Verreault (Univ. of Quebec at Chicoutimi, Canada) where he suspects anisotropy in the mounting on the roof beam in my house I decided to do experiments with free runs. The idea is that the behaviour of the free running pendulum, when started from different angles, shines some light on the nature of the anisotropy. For that reason I've chosen angles just before and after the transitions in the ellipse's rotational direction and more halfway in the first and fourth quadrant. +96, +89, +60, +45, +30, +04, -05, -30, -60,
The 90 degree angle is here carefully aligned with the roof beam, and differs some 15 degrees from the real north.
We list the experiments in the order of the precession angle at which the drive was stopped, starting at +94 degrees and going CW.
The procedure is: Let the pendulum run normally until the intended precession angle is reached, then switch off the drive pulses and let the pendulum decay it's amplitude for some 2 hours. Then switch on the drive pulses again.
During each experiment we take screenshots from the compass display at 1 minute intervals and afterwards process them into an animated picture.
It is not only interresting to see the decay process, but also how the amplitude and the elliptical rotation restores after switching on the drive pulses.
We must realize that during the process of restoring the amplitude the drive timing (the distance fron the center at which the impulse is given) is not well according to Schumacher's equation [19], because the amplitude is not yet at the correct value. This will influence the precession during that process.
The animations were made using Imagemagick on a Linux Mint 21 computer with the command: convert -delay 4 -loop 0 *.PNG MyAnimation.gif
in the directory with the .PNG images. The text images were inserted during the postprocessing.
Conclusions (preliminary)
When the drive is stopped near the X-axis little precession of the free running pendulum is seens. +04 and - 05 degrees).
Near the Y axis this seems also the case, but less convincing.
The precession during the "return to normal amplitude", when the drive is switched on again, is generally very fast, with the exception of the measurement starting at +60 deg. Here the return process started at a moment where there was little ellipse.
I have planned to do a follow-up after the mounting construction on the roof has been improved.
+96
Experiment +96 degrees
2025-07-16_16:00 at +102 deg: Start animation
2025-07-16_16;28 at +96 deg: Drive OFF
2025-07-16_18:37 at +63 deg: Drive ON
2025-07-16_21:14 at +78 deg: End of animation
+89
Experiment +89 degrees
2025-07-17_09:56 at +102 deg: Start animation
2025-07-17_11:04 at +87 deg: Drive OFF
2025-07-17_13:49 at +19 deg: Drive ON
2025-07-17_17:24 at +113 deg: End of animation
+60
Experiment +60 degrees.
2025-07-14_08:50, at +70 deg, Start animation.
2025-07-14_09:47, at +60 deg, Drive OFF.
2025-07-14_12:32, at -30 deg, Drive ON.
2025-07-14_13:52, at -45 deg, End of animation.
+45
Experiment +45 degrees.
2025-07-12_14:12, at 67 deg. Start animation.
2025-07-12_16:14, at 45 deg, Drive OFF.
2025-07-12_19:26, at -38 deg Drive ON.
2025-07-12_22:41, at -148 deg End of animation
+30
Experiment +30 degrees
2025-07-13_12:25, at 45 deg. Start animation
2025-07-13_13:44, at 28 deg, Drive OFF.
2025-07-13_16:30, at -28 deg Drive ON.
2025-07-14_01:00, at 169 deg End of animation. I let it run to show the whole 3rd quadrant.
+4
Experiment +04 degrees
2025-07-16_09:32 at +30 deg: Relaunch.
2025-07-16_10:03 at +22 deg: Amplitude has stabilized. Start animation
2025-07-16_11:28 at +04 deg: Drive OFF
2025-07-16_13:51 at - 02 deg: Drive ON
2025-07-16_09:32 at - 75 deg: End of animation
-5
Experiment -05 degrees
2025-07-19_08:41, at +13 deg, Start animation.
2025-07-19_10:11, at -5 deg, Drive OFF.
2025-07-19_13:50, at -1 deg, Drive ON.
2025-07-19_15:38, at -109 deg, End of animation.
-60
Experiment -60 degrees.
2025-07-14_13:37, at -42 deg, Start animation.
2025-07-14_15:09, at -60 deg, Drive OFF.
Notice the precession now goes CCW, same as the elliptical rotation.
2025-07-14_17:07, at -32 deg, The amplitude had become so small that no CenterPasses were detected anymore and the data logging stopped.
Only the Compass Display showed the bob's movements as white dots.
The amplitude decreased further and the elliptical path became almost circular.
2025-07-14_20:00, at -32 deg, Drive ON.
Because stil no CenterPasses were detected and the system was out of sync the DrivePulses came at much lower frequency, and the bob's path
shows a very rapid precession, without the amplitude increasing.
2025-07-14_20:57, Bob relaunced in X-direction at a small amplitude.
We see the amplitude grow rapidly and the elliptical rotation takes the "normal" direction for that quadrant.
2025-07-15_00:00, at 135 deg, End of animation.