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Old 12-09-2018, 12:12 PM
DavidQ DavidQ is offline
Craftsman
 
Join Date: Aug 2011
Location: Washougal Washington
Posts: 375
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Quote:
Originally Posted by chejay
Has anyone found a way to "make" OR simulate a singular, axial ring fin?

I have two methods. One for appearance, and one for "stability".

For appearance, I use the "inner tube" as the ring, and oversize it so that it looks like an outer tube. That lets me model the shapes and appearances. But, it doesn't compute the stability, since OpenRocket ignores outer tubes for that.


For stability, I take out the inner tubes that look like ring fins, and replace them with an OpenRocket ring fin of the same size as the axial ring fin. Their fins are not axial, but are attached to the outside of the rocket. By selecting only 1 fin, OpenRocket can do a best guess at the center of pressure calculation. The center of mass should still be the same, ignoring that it would be off-axis.

I attached a simple rocket to illustrate this. One is the ring fin in an axial position, by using an inner tube. The other is the ring fin in a tangent position, using a single tube fin. There is no engine or mount or chute, because my rockets usually don't need them to fly straight and true. Magic!
Attached Thumbnails
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Name:  ringfin.png
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Name:  ringfin stability.png
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Size:  73.9 KB  
Attached Files
File Type: ork ringfin.ork (1,000 Bytes, 37 views)
File Type: ork ringfin stability.ork (941 Bytes, 37 views)
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