How to create / simulate a ring fin in OR..?

[rstaff3]

Thanks again to everyone who has contributed to answering my question.



Ah - does RockSim allow accurate aerodynamic ring fin simulations? (I've never tried it..)

I can not vouch for exactly how accurate. It has worked fine for the handful that I have simmed. That means I used the 1 caliber rule based on the sim and the chosen delay was close enough to bring them back unharmed. Except for that one time a nose cone suck.

 

[rstaff3]

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?

OR is still based on Barrowman too. Likely an extension, but developed by who? Verified as legitimate and accurate by who?

I strongly suggest that folks who have not done so read the Barrowman report to understand the assumptions and possible limitations. Link follows, and username and password are both guest.

https://www.rocketryfiles.com/?p=home&d=Technicalarticles/

All the weird extensions - ring fins included - require the "RockSim" method vs Barrowman.

 

[markkoelsch]

All the weird extensions - ring fins included - require the "RockSim" methon vs Barrowman.

That is true. The intent of my previous post is beyond ring fins- people should have an understanding of where this stuff is coming from, and Barrowman is that source. Extensions or straight- knowledge is a good thing.

 

[rstaff3]

That is true. The intent of my previous post is beyond ring fins- people should have an understanding of where this stuff is coming from, and Barrowman is that source. Extensions or straight- knowledge is a good thing.

I agree and didn't mean to infer you didn't know this. Just FYI for the rank and file

 

[dhbarr]

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?

OR is still based on Barrowman too. Likely an extension, but developed by who? Verified as legitimate and accurate by who?

I strongly suggest that folks who have not done so read the Barrowman report to understand the assumptions and possible limitations. Link follows, and username and password are both guest.

https://www.rocketryfiles.com/?p=home&d=Technicalarticles/

Because Dahlquist & Galejs are widely available? Perhaps if I get some free time I'll try and knock some rust off the ol' grey matter and try to read some OR code.

 

[aerorocket]

Several years ago I developed a Ring-Fin drag coefficient approximation for AeroDRAG based on AeroRocket wind tunnel experimentation. Later, I gave Tim VanMilligan the curve fit equations so he could incorporate the Ring-Fin equations into RockSim version 7 and 8. I assume those same equations are still part of RockSim but I cannot be sure. There are only a few variables required to design a Ring-Fin so the incorporation of a Ring-Fin design based on the RockSim CAD model was relatively simple according to Tim. Ask Tim if the Ring-Fin equations are still part of RockSim.

John

 

[markkoelsch]

Because Dahlquist & Galejs are widely available? Perhaps if I get some free time I'll try and knock some rust off the ol' grey matter and try to read some OR code.

While something of a thread high jack, please post links to both. I recall reading Galejs at some point, but not sure if I came across the Dahlquist.

 

[markkoelsch]

Here is the link to Robert Galejs article:

https://argoshpr.ch/joomla1/articles/pdf/sentinel39-galejs.pdf

 

[markkoelsch]

The updated Bob Dahlquist article.

https://www.apogeerockets.com/Wind_Caused_Instability