OR Ring Fin Simulation

How can I "make" OR simulate a single ring fin centered along the axis? It handles ring fins attached at rocket body surface fine, but seems to have trouble aligning one in the center.

Try the techniques used in this document from Apogee, intended for RockSim:
https://www.apogeerockets.com/education/downloads/Newsletter27.pdf
Also, see this previous thread:
https://www.rocketryforum.com/threads/how-to-create-simulate-a-ring-fin-in-or.137773/

Tube fin or Ring fin? Tube fins are attached to the airframe and OR sims them well enough. Ring fins are usually a single large ring with standoffs or some other attachment method. The Estes Super Neon is an example of a tude fin and the Sirius Rocketry Eradicator is an example of a rocket that has a ring fin. OR doesnt currently support Ring fins, but there are ways to make them appear on the 3D model. For simulation you could probably use several tube fins of the same surface area as the single ring fin.

All good suggestions, and thanks.
I substituted a set of flat fins with the same surface area as the original ring fin, adjusted the area down to compensate for air-flow reduction when the body tube passes through the ring fin, and washed it thru OR one more time -- by the simulator it should be totally stable (1.87 cal.) Having built, and flown this model, it was completely unstable, even dangerous, a real land shark. What else have I overlooked? For the test flight, I didn't have very large engines onboard (C6-7/B6-0 configuration), could it simply been underpowered?
Attached is a PDF of the replacement fin design as well as an .ORK file to run on OR.
Jay Edmondson

I would say a B6-0 would indeed be quite underpowered for that. OR shows mass with motors at 5.35 oz (did you weight it?), Estes engine chart lists maximum liftoff weight for that rocket as 4 oz, so you're quite a bit over the max. Sim showed 22 mph off a 4 ft rod, which is very slow. I don't know if there are any other stability issues (it *looks* like it should be OK to my eyeballs) but you definitely flew underpowered. That thing needs a 24mm motor to get off the pad, unless you've go some old vintage B14s or something lying around.