Found myself sharing a “pod” with my grandkids, on this iconic amusement park ride last week. It was one of my favorites as a kid. The shared hilarity of unpredictable centrifuge spins made up for the queasiness I felt afterward. Plus, the mechanism causing those chaotic spins (some in the direction of the carousel’s rotation, some in the opposite) intrigued me… wonder if I can simulate it?
Took me an embarrassing amount of time, but I learned (and relearned) a bunch – mostly that I need a better grasp on tangents, normals, and orientation in general! I gave up on getting actual “pods” to work in the sim, but include my disabled attempt in the script:
tilt a whirl K2c.gh (31.7 KB)
Actually, I would like to know what I’m doing wrong (though this is an accurate picture of how my stomach felt when the ride finished):
Here you go!:
tilt a whirl K2c VR 1.gh (45.0 KB)
where line SDL starts at the origin.
The problem is that you are giving Orient a line as a target plane. It will take the line as vector and interpret this as the Z-component of the target plane. This does not determine how the x andy axes are oriented (in rotation) to that z-axis, however, and Grasshopper is doing this… by some method. Probably based on the world XY.
Thank you @Volker_Rakow – so much more satisfying! (And nice explanation, plus clean up of my unnecessary transformations 
)
Post the finshed simulation video!
After playing with the sim, I found that it’s tricky to get various parameters right for the the pods to make it all the way around over the humps. I suspect the over-hump frequency has to play nice (or naughty depending on how you look at) with the pod’s pendulum frequency. Then I started to wonder who came up with this?! Turns out it’s a hundred years old, and invented about an hour away 
