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  #1  
Old 01-18-2009, 12:04 AM
Tau Zero's Avatar
Tau Zero Tau Zero is offline
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Talking RockSim Tips & Tricks

Elsewhere on YORF, Don "Barone" Fent and that Craig McGraw boy observed:
Quote:
Originally Posted by barone
Maybe we need a "RockSim" section here in the forum under "Workbench" where people who have a RockSim specific question can ask it and those really knowledgable about the subject can inform us. I know there's bits and pieces posted all over this forum but maybe a dedicated section would be helpful? [SNIP] it would be really nice to find all the info in one spot instead of surfing the forum trying to find it.....
Quote:
Originally Posted by CPMcGraw
Maybe we should create a new thread...?
So here we go.

In the interest of keeping the content of this particular thread on-topic , please limit your questions and answers to the following loose but specific parameters :

Q. "I have RockSim [specify version here]. How do you make ring and tube fins sim accurately?"

A. "That will require borrowing a technique pioneered by Bruce S. 'teflonrocketry1' Levison, who is a qualified RockSim guru. Here's how Bruce does it..."


Each of us who have been bashing around with RockSim for a version or three have either managed to come up with our own little tricks, or learned and borrowed from other people (or each other). And migrating between versions can require some adjustments, too. ("What the hey? I *used* to be able to do that with the old version of RockSim? What gives with *this?*"


So here we go. (Parent's voice) "I don't think I need to remind you boys and girls to play nice."


Cheers,
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03 Sept 2014
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  #2  
Old 01-18-2009, 01:21 AM
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Default How To: Compound Components

A compound component is where you merge the properties of two simple database components together to create a third component, which you cannot save to the database. The attached files show an example of this. I have created a transition to use with Estes BT-50 and BT-60 tubes, and which has a 1" wide base on the BT-60 end. The shoulder for the transition is still available as it would be with any other.

The idea is relatively uncomplicated. Start with your transition. Go into the edit dialog for the transition, and click the "Shoulder" tab. Locate the "Length" for the end you are adding the extension to, and increase the value found here by the length of the extension. Change the name of the component to some descriptive identifyer, and add "Front" in parentheses. Make sure the Material is "Balsa" (or whichever material you want it to be). Close this dialog. The shoulder is now very long on the 2D and 3D display screens.

Now, add a 1" length of standard tubing (in this case, BT-60) to that end of the transition. Open up the editor dialog for that piece of tube, and locate the "Material" drop-down box. Change the type of material, and the part name to match that of the original cone section, but add "Rear" in parentheses. Close the dialog.

You now have the equivalent of a single-piece component.
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Name:  TR-5060-2 Demo Pattern 2D.jpg
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File Type: rkt TR-5060-2 Demo Pattern.rkt (12.3 KB, 80 views)
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  #3  
Old 01-18-2009, 01:48 AM
James Pierson James Pierson is offline
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Thumbs up Think "BIG" Jay

Although a new thread about Rocksim is great however I personally would like to see a new Forum Title under the Workbench section. Something like "Rocksim Asylum" or something of that nature. Besides we could have many threads under such an area. We definely need to get all the DATA files in a neat thread along with the component parts, tips and tricks, etc... Just my two cents worth, JP.

We would be the first Forum to have an exclusive "Rocksim" thread to my knowledge.

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  #4  
Old 01-18-2009, 02:09 AM
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Default

Quote:
Originally Posted by James Pierson
Although a new thread about Rocksim is great however I personally would like to see a new Forum Title under the Workbench section. Something like "Rocksim Asylum" or something of that nature. Besides we could have many threads under such an area. We definely need to get all the DATA files in a neat thread along with the component parts, tips and tricks, etc... Just my two cents worth, JP.

We would be the first Forum to have an exclusive "Rocksim" thread to my knowledge.

James Pierson
NAR# 77907


Some have also mentioned "SpaceCad", so maybe a "Software" section with "RockSim" and "SpaceCad" as primary sub-threads. I know Scott could add them, but the question is do we need a "top-level domain" type of category (like Workbench, or Swap Shop) for this? I'm 50-50 with the idea. Most of us use RockSim, but I've never seen anything drawn up with SpaceCad. Does anyone here actually have it installed, and use it?

Might be something to have some discussions about, before setting it up.
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  #5  
Old 01-18-2009, 02:17 AM
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Mark II Mark II is offline
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Hey, Jay! What do you say?

OK, here's my first dilemma. I whipped up a RockSim 8 clone of the Centuri Groove Tube #KA-11. Everything is done per the plans found at JimZ's site, and it is built with parts from Semroc. The result matches up pretty well with the rocket's vital statistics shown in the 1972 Centuri catalog at Ninfinger.

The recommended engines are A8-3, B4-4 and C6-5.

Here are my results:

Length: 18.35"
Diameter: 0.908" (ST-8)
Fin Span: 2.724"
Weight: 1.5 oz

All simulations use a 48" x 1/8" rod.

A8-3........79.6'......Dv 42.6 FPS
B4-4........99.2'......Dv 70.6 FPS
C6-5........105.6'.....Dv n/a

The rocket is unstable using all recommended engines.

What am I missing?


Mark \\.

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  #6  
Old 01-18-2009, 02:17 AM
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Default

Quote:
Originally Posted by James Pierson
Although a new thread about Rocksim is great however I personally would like to see a new Forum Title under the Workbench section. Something like "Rocksim Asylum" or something of that nature. Besides we could have many threads under such an area. We definely need to get all the DATA files in a neat thread along with the component parts, tips and tricks, etc... Just my two cents worth, JP.

We would be the first Forum to have an exclusive "Rocksim" thread to my knowledge.

James Pierson
NAR# 77907


Getting back to your idea, James...

Having a thread under the "Workbench" category... RockSim technical discussions do tend to get buried in other threads, don't they? Maybe we do need a way to bring them out into the sunshine. What do you think about having a whole category (like Workbench and Swap Shop) dedicated to RockSim, or "Software", with RockSim as a sub-category?

Sorry for this habit of thinking out loud...
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  #7  
Old 01-18-2009, 02:36 AM
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Default

Quote:
Originally Posted by Mark II
OK, here's my first dilemma. I whipped up a RockSim 8 clone of the Centuri Groove Tube #KA-11. Everything is done per the plans found at JimZ's site, and it is built with parts from Semroc. The result matches up pretty well with the rocket's vital statistics shown in the 1972 Centuri catalog at Ninfinger.

The recommended engines are A8-3, B4-4 and C6-5.

Here are my results:

Length: 18.35"
Diameter: 0.908" (ST-8)
Fin Span: 2.724"
Weight: 1.5 oz

All simulations use a 48" x 1/8" rod.

[/font]
A8-3........79.6'......Dv 42.6 FPS
B4-4........99.2'......Dv 70.6 FPS
C6-5........105.6'.....Dv n/a
[/b]


I just fed the data into my copy, and got the same results, so it's RockSim not liking something. Let me look at one of my tube-fins and see what I did differently. I'll post later...

It's 1:37 in the morning, and my brain is whining...
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  #8  
Old 01-18-2009, 02:40 AM
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Tau Zero Tau Zero is offline
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Thumbs up Centuri Groove Tube -- RockSim 7

Quote:
Originally Posted by Mark II
Hey, Jay! What do you say?

OK, here's my first dilemma. I whipped up a RockSim 8 clone of the Centuri Groove Tube #KA-11. Everything is done per the plans found at JimZ's site, and it is built with parts from Semroc. The result matches up pretty well with the rocket's vital statistics shown in the 1972 Centuri catalog at Ninfinger.

The recommended engines are A8-3, B4-4 and C6-5. [SNIP]

The rocket is unstable using all recommended engines.

What am I missing?
Here's how the aforementioned Bruce S. Levison did it in RockSim 7 (see attached file originally downloaded from The Rocketry Forum [TRF]). He did it to contrast how inaccurate RockSim 8 was with its tube fin calculations.

Of course, now that I look at it, I realize *I* may have been misinterpreting the way Bruce models tube fins. On the other hand, I think I have *ring* fins down okay, since Bruce was kind enough to look over an early version of my Tau Zero design and tweak it so it actually worked.


Cheers,
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File Type: rkt Centuri_Groove_Tube_RS8_Bruce_Levison.rkt (47.1 KB, 74 views)
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Jay Goemmer
"Centuri Guy"/"Tau Zero"
Semroc SAM #0029
NAR 86131


“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

Last edited by CenturiGuy : 01-18-2009 at 03:01 AM.
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  #9  
Old 01-18-2009, 02:55 AM
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Tau Zero Tau Zero is offline
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Wink A Modest Proposal...

Quote:
Originally Posted by James Pierson
"Think BIG Jay"
Jim, that *really* hurts my head.


Quote:
Originally Posted by James Pierson
Although a new thread about Rocksim is great however I personally would like to see a new Forum Title under the Workbench section. Something like "Rocksim Asylum" or something of that nature. Besides we could have many threads under such an area. We definely need to get all the DATA files in a neat thread along with the component parts, tips and tricks, etc...
Quote:
Originally Posted by CPMcGraw
Having a thread under the "Workbench" category... RockSim technical discussions do tend to get buried in other threads, don't they? Maybe we do need a way to bring them out into the sunshine. What do you think about having a whole category (like Workbench and Swap Shop) dedicated to RockSim, or "Software", with RockSim as a sub-category?
Gentlemen,

I humbly recommend that we blend your suggestions thusly:

Workbench / Software / RockSim Asylum (with multiple threads)


"Gather ye inmates, while ye may..."


LTV Scott , is this doable? And do we need any further discussion on the matter?



Submitted for your consideration,
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Jay Goemmer
"Centuri Guy"/"Tau Zero"
Semroc SAM #0029
NAR 86131


“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014
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  #10  
Old 01-18-2009, 03:23 AM
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Mark II Mark II is offline
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Quote:
Originally Posted by CenturiGuy
Here's how the aforementioned Bruce S. Levison did it in RockSim 7 (see attached file originally downloaded from The Rocketry Forum [TRF]). He did it to contrast how inaccurate RockSim 8 was with its tube fin calculations.

Of course, now that I look at it, I realize *I* may have been misinterpreting the way Bruce models tube fins. On the other hand, I think I have *ring* fins down okay, since Bruce was kind enough to look over an early version of my Tau Zero design and tweak it so it actually worked.


Cheers,

OK, Bruce Levison's RS8 version looks almost identical to mine, yet his version works (at least for BP A's and B's) and mine doesn't. I don't see what the critical difference is. Can anyone point out what I am missing?

I encountered this same problem when I tried to simulate a Quest Totally Tubular. That's what caused me to think that there was something very odd about the way that RS does tube fins.

BTW, what are those extra fin-like structures in the tubes in the RS 7 version of Bruce's file? What the heck is that all about? And what is that blue star-like structure at the base of the main BT in your file?

Finally, you mention ring fins. Does RS do something weird with them, too? (See next post.)

I like RockSim's concept, its execution and its polish. I want to keep this on topic and find answers about these particular things, in order to gain some insight and learn a trick or two or a tip that I can use in the future.

If Scott creates a new subsection under the Workbench as James and Jay propose, then I'd be happy to confine the discussion of this one issue to one particular thread within it. That would work well, I think.

I think that the proposed subsection should be confined to talking about specific techniques, solving specific problems and answering specific questions. IOW, "hands-on" stuff. (Conceptual ranting about the program itself or anything else, which I am as prone to doing as anyone else, could still be done in other places, just not there. )

Mark \\.
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Last edited by Mark II : 01-18-2009 at 05:08 AM.
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