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Senior Space Cadet

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I wasn't sure where to put this, but I assume other's, still on the lower slopes of the learning curve, might have these same questions.
After seeing what Neil_W, and others, can do, with Open Rocket, it is obvious that a lot more can be done than I am currently capable of.
My most pressing ignorance is in shaping fins. I'd like to be able to make more curvaceous fins.
I just figured out that you can add more points in FreeForm, but I don't see a way of turning it into a flowing curve. Fairing would be the term in boat design.
The second thing I might like to do is add motors to the outside of the body tube, with nose cones on them. In effect, clustered body tubes.
Then, I'd want to be able to rotate them, or the fins, so that they aren't in line or on top of each other.
If you guys can explain how to do these things, it would be a great help.

Sometimes, in my enthusiasm and eagerness to learn, I get a little carried away. I've been accused, by one of this forum's members, of hijacking another's thread.
I think hijack is too strong a term, but maybe I did insert myself too aggressively. For that, I apologize. I'll try and do better.
 

Senior Space Cadet

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Ooops! Just found the rotation button. Thought it was for spin.
Still need to know how to make smooth flowing fins and add nose cones to tubular fins.
 

neil_w

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There are two ways to do curvy fins:
1) Insert lots and lots of points, and do it by hand. This is usually what I do. It is tedious but works.
2) Create an image of your fin shape in a drawing program:
a) Make the drawing of the fin solid black on white background
b) Create a freeform fin set, edit shape, and then import from image:
1594750331218.png

I don't recall the required orientation of the fin shape in the image. Easiest enough to figure out by playing.

As for this:
The second thing I might like to do is add motors to the outside of the body tube, with nose cones on them. In effect, clustered body tubes.
Not possible in the current version of OR. Will be possible in the next release, coming out... eventually. Hopefully this year.
 

Senior Space Cadet

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I'm making progress with Open Rocket. I've only been doing it a few weeks. I don't know whether I'm progressing slow or fast.
Here's what I was able to do a few minutes ago. I need to add windows and such to make it an interstellar space craft. Haven't gotten that yet.
Screenshot 2020-07-14 16.37.44.png
 

Senior Space Cadet

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There are two ways to do curvy fins:
1) Insert lots and lots of points, and do it by hand. This is usually what I do. It is tedious but works.
2) Create an image of your fin shape in a drawing program:
a) Make the drawing of the fin solid black on white background
b) Create a freeform fin set, edit shape, and then import from image:
View attachment 424473
I don't recall the required orientation of the fin shape in the image. Easiest enough to figure out by playing.

As for this:

Not possible in the current version of OR. Will be possible in the next release, coming out... eventually. Hopefully this year.
I'll play around with it. This is similar to how my boat CAD program works, minus the auto fairing. I'm sure I can get close enough to what I put on the rocket to get an accurate CP. Thanks for the help.
 

scschulte

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I cannot get Open Rocket to "open" on my Mac running Mac OS 10.14.6 Mojave. Seems Java is needed and I downloaded what the program seemed to indicate was required-- but it would not run. I'll keep researching this but if anyone is on a Mac using Open Rocket -- I'd appreciate any pointers on how to get it to start.

Thanks,

Steve
Wednesday 15 July 2020
 

neil_w

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I cannot get Open Rocket to "open" on my Mac running Mac OS 10.14.6 Mojave. Seems Java is needed and I downloaded what the program seemed to indicate was required-- but it would not run. I'll keep researching this but if anyone is on a Mac using Open Rocket -- I'd appreciate any pointers on how to get it to start.
 

scschulte

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WOW! That did it! Open Rocket is running on my Mac!! My Endeavour seems to run fine-- I mean the Open Rocket results are similar to my actual launch last Sunday. But the LOC/Precision V2 has a message about fins not allowed on a transition so the V2 loads without fins and I'm not sure how to add them. OK well I'll play with this now that it is running!!! Thanks VERY MUCH!!

Best regards,

Steve Schulte
Wednesday 15 July 2020
 

neil_w

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But the LOC/Precision V2 has a message about fins not allowed on a transition so the V2 loads without fins and I'm not sure how to add them.
The current version of OR does not allow you to attach fins to a transition. To get around this, add a body tube *after* the transition, automatic diameter, length 0. Attach the fins to that body tube. There will be a slight inaccuracy (it will be a bit optimistic with CP) but overall it's a good enough approximation.
 

JoePfeiffer

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It was interesting to read Tim van Milligan's notes on how Rocksim manages fins on transitions the other day -- it treats the fin as if it were attached to a tube with a diameter that's the average of the fore and aft diameters of the transition. It ought to be possible to get this effect in OR by having a first-half transition, then a 0-length tube (attach fins here), then a second-half transition.
 

Nytrunner

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It ought to be possible to get this effect in OR by having a first-half transition, then a 0-length tube (attach fins here), then a second-half transition.
You can just put a zero mass, zero thickness tube at the end of the transition that has a diameter same as the transition midpoint. It'll throw a body-discontinuity error, but I don't think it should affect the CP. Try it out
 

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