Yeah, this. Can OR make said fins transparent?There's a Peak of Flight article about approximating the equivalent affect on Cp using flat fins.
Here it is:
No.Yeah, this. Can OR make said fins transparent?
They should, considering OR webpage says this:I wish the OR guys had a more active presence here.
Does either method give accurate analysis? That is what is important with a new design.At this time, there are two methods of creating ring fins... using an externalized "Inner Tube", and a multiple body tube method.
For these methods, Each separate part (all fins will be considered one part) has been given a separate color for clarity.
The inner tube method will give you an accurate appearance, but the ring it generates doesn't get calculated aerodynamically.
The multiple body tube method breaks down the inner body tube into separate segments. This method also uses an externalized inner tube (in this case the red section) to simulate the body tube under the ring fin, the ring fin is a body tube itself.
The inner tube method would need a phantom body tube to "attach" fins to it (such as you find with the Ram Jet), whereas the multiple tube method wouldn't need it.
Both methods can be decorated with "decals" to give accurate appearances.
While flawed, of the two methods, the multiple body tube method would likely be the more accurate version.Ok, that is what I thought. So really it is only useful for making a pretty picture versus predicting anything having to do with the stability and performance of the rocket.
Ah - does RockSim allow accurate aerodynamic ring fin simulations? (I've never tried it..)I likes my RockSim.
Without commenting on its accuracy, we can at least say Rocksim at least recognizes ring fins as a design component and attempts to simulate them. I'd assume that they're at least reasonably approximated.Ah - does RockSim allow accurate aerodynamic ring fin simulations? (I've never tried it..)
The photos are showing a tube fin rocket...I have done a ring tube rocket here on TRF as found on
OK, yes, I see that ring-fins are different.Ring fins are different...
Rocksim is not as bad at Mach as folks like to say. That said, I cannot comment on it above Mach 1.5 or so as I do not have data to compare- I have not flown faster, so I do not have data to judge.I think Rocksim does a more refined job of locating the center of pressure. OpenRocket uses much stricter geometry definitions and gives a conservative (forward) CP position.
That being said, Rocksim wigs out going through Mach (or so I heard), and OpenRocket behaves better.
Still, the more versatile geometry allowable makes me consider getting it one day so I can perhaps characterize odd designs and extrapolate for scale-up.
Why would that surprise you? Rocksim has straight Barrowman, and the Rocksim method, which is an extension of Barrowman. No mention of Dahlquist or Galejs. If they were involved, or their work was used don't you think it would be mentioned?Unmodified Barrowman, not Dahlquist or Galejs? That would surprise me.