Collisions and crashing

I know next to nothing about scripting or the physics of SL, so please be gentle. Maybe my problem will be solved once the Havok 4 is in place, but here's my problem:

I built a suspended roller coaster. The car hangs below a monorail track which is cylinder shaped. A pole connects the rider's seat/chair to a large donut shape above it which encircles the rail completely. I use a modified airplane script to move the donut along the track. The car swings out freely left and right and sometimes all the way around, whenever the car takes a turn or loop. The swinging is not scripted.

I can usually ride the circuit two times in a row without a problem. But the third time is not charm. I often go careening off-world or the car simply falls through the monorail as if it had become phantom. Or best of all, I crash the sim.

So is my problem that I'm creating too many collisions between the car and the rail and SL gives up? Is it fixable? Or is it voodoo?

Welcome to the wonderful world of Havok 1 physics.

Objects that interpenetrate one another (and a cylinder going through the hole in a torus is still considered an interpenetration by the physics engine, strangely enough) cause the physics engine to go weird. It is the same problem with creating realistic chains with links, and towing physical objects with linkages. It just doesn't work very well.

No, unfortunately, there is no "work around" for the problems you are experiencing, until Havok 4 is released. It is endemic to the woes of the physics engine itself, and not likely to be resolved without changing that foundation.

Thanks. I was afraid that was the answer.

And by the way, what happened to Havoks 2 and 3?

http://www.youtube.com/watch?v=sdUIqvkzfdQ

havok 1 likes to crash with this type of "roller coaster".

And it will not work on havok 4 for the moment.

I took it out for a spin on/with the Havok4 Beta version yesterday and it worked like a charm. The script did act a little more subduedly (if that's a word). The side to side swings weren't quite as violent (translated: fun) as in regular old SL.