OpenRocket vs. the Dark Matter Probe

The latest Apogee Peak of Flight newsletter includes a link to a plan from Shrox called the Dark Matter Probe. It's provided as a RockSim file; normally a rocket which is as (relatively, for Shrox) simple as this one would load fine in OpenRocket, but the latest 14.06 version doesn't get the fins.

Any suggestions for someone without the cash to buy RockSim?

The Rocksim design uses both SubAssemblies and Pods where the fin sets are attached. Neither are supported in OR. For this particular design the fins should be able to be modeled in OR - but will require some enhancements to the Rocksim parsing logic. The body tubes on the ends of the fins will not be supported though as there is no ability in OR to do that at this time.

I'll try to find time to implement this and get a pull request to Kevin.

Regards,
Doug

View attachment DarkMatterProbe02.ork

Here's an OR representation, minus the tubes on the ends of the fins. I've modified the OR code to create this but still needs some cleanup and testing.

Interestingly, the Rocksim file has an invalid tube coupler - the OD is smaller than the ID. Rocksim happily allows this and keeps both values, but renders it using ID. That's not allowed in OR so the OD gets defaulted to the ID in that case, making for a larger tube coupler than desired.

Regards,
Doug

Hey, thanks! I think I can figure out how to get tube on the ends of fins...

I just opened the Dark Matter Probe in Rocksim. It is basically a 29mm minimum diameter rocket (no motor retention) Using some of the bigger 29mm motors the simulation results show altitudes to over 5000 feet! No wonder why it uses a streamer

View attachment DarkMatterProbe02a.ork

With a little bit of trickery I was able to fake it into having tubes on the ends of fins. No guarantees about the aerodynamic computations with those things hanging out there, but at least it makes for a more realistic look.

Cheers,
Doug