Now you you are getting into the Physics of Mass. An object in motion has momentum. The larger the mass the more the momentum. So I would think the heavier bob would take longer to become still. But I could be wrong. Someone may correct me.

The drawback to this rig is you will get motion of the airplane and plumb bob with each adjustment. The key is to minimize the motion. That is why I made the windlass set up in the dowel. I still get motion but not as much as grabbing the dowel and twisting. When I do get movement I just use a finger to counteract the movement on both the plane and the bob. It settles down fast. I do this in my totally closed up garage so wind is not a factor.