Oh, I think I know what the problem is. Man, I’m having trouble with this myself. The issue is that the Set Rotation node sets the object rotation, which is actually relative to the transformation of its parent, in this case the boom. You would need to set the global rotation of the object, which is something that I have been trying to do, but I’m having a lot of weird trouble with the math. 
I’ve been trying to add a “World Space” option to the Rotate Object node. Until that gets figured out I don’t know that you’ll be able to do what you’re trying to.
I like your scene, though. 