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Fin Alignment Templates - Rocksim 9?

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pcotcher

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I need to generate some fin alignment templates, and have odd sized tubes, and odd numbers of fins - I need a three fin and LL template for a BT80, and then a eight fin template for a ST18 -

Normally I'd just pull this out of some other kit, but don't have anything for those sized tubes.

I have Rocksim 9 - but haven't been able to find how to generate something like this from within that software.

Anything else out there that will help with this?

Thanks,

Paul
 

kandsrockets

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VCT has a free download toolkit that has a program to make any fin template you need.
 

KerryQuinn

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I wrote a utility that will make estes-style wrap-around alignment guides for fins and launch lugs from OpenRocket models. I made up 2 dummy rockets using the tube sizes and number of fins you described. After you download it from TRF, change the filename from "bt80tube.htm.txt" to be "bt80tube.htm" and then you can view it with internet explorer. I had to change the name because TRF wont let us upload files with the *.htm extension). Each file has a square in it which should should print out to be exactly 1.00" x 1.00" on your printer. There is also a "dummy" fin template on the printout that you can ignore.

The latest version of OpenRocket (1.0.x) has a capability to import RockSim model files.

You can download my openrocket utility at:

http://www.foxvalleyrocketeers.org/myframes/reports.htm

All high-tech aside, you can create your own alignment guide with a strip of paper that is 3.14159 x diameter in length and 1/2" wide. Carefully measuring and putting marks that are (3.14159 x diameter)/(# fins) apart will work just fine. (I hope there are no spies out there trying to steal this top secret rocket building technology. :) )


-Kerry

View attachment bt80tube.htm.txt

View attachment st18tube.htm.txt
 
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Mike Howie

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VCT has a free download toolkit that has a program to make any fin template you need.
My copy of VCT got trashed. I can find the VCP page no problem, but can't
seem to find the VCT page. Any clue where I should look?
 

pcotcher

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I wrote a utility that will make estes-style wrap-around alignment guides for fins and launch lugs from OpenRocket models. I made up 2 dummy rockets using the tube sizes and number of fins you described. After you download it from TRF, change the filename from "bt80tube.htm.txt" to be "bt80tube.htm" and then you can view it with internet explorer. I had to change the name because TRF wont let us upload files with the *.htm extension). Each file has a square in it which should should print out to be exactly 1.00" x 1.00" on your printer. There is also a "dummy" fin template on the printout that you can ignore.

The latest version of OpenRocket (1.0.x) has a capability to import RockSim model files.

You can download my openrocket utility at:

http://www.foxvalleyrocketeers.org/myframes/reports.htm

All high-tech aside, you can create your own alignment guide with a strip of paper that is 3.14159 x diameter in length and 1/2" wide. Carefully measuring and putting marks that are (3.14159 x diameter)/(# fins) apart will work just fine. (I hope there are no spies out there trying to steal this top secret rocket building technology. :) )


-Kerry
Okay, so those guides worked great, and I downloaded your utility to try to make a further one, but couldn't make any sense of how to get it running, or how to get to the point where I could make a new template.

So I tried to go into excel and make the precise measurements - pi*D and all that - pretty easy stuff, came up with the four subdivisions, but then couldn't figure out how to plot the data properly.

I need to figure out a way to do this easily, as I don't want to keep coming here to ask for help. I'm working on a four fin template for a 3.1" Loc tube -normally it wouldn't matter in this size, as the main fins are always pre-slotted, but in this case, it does, as these are small detail fins that are being surface mounted. Heck a four fin template like the one above with the different tube sizes would be great at this point.

Excel would be perfect, except it seems to only think in business, and as soon as you want to do something engineering, it gets less useful.

Will keep playing around to see what I can come up with (I just kluged a template together making boxes in Publisher based on the dimensions in Excel, and then exactly overlaying them - crude, slow, but effective I guess).

Paul
 
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NjCo

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(I hope there are no spies out there trying to steal this top secret rocket building technology. :) )

-Kerry
:)

I just got this visual of NASA engineers with a huge paper wrap and the Saturn V body tube! High tech indeed.
 

KerryQuinn

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Hi Paul -
Sorry you had problems getting the utility to work. You can PM me with your email address if you'd like some help.

I made up a dummy rocket in OpenRocket that has a 3.10" diameter tube (is that the exact diameter of LOC 3.1 tubing - I'm not sure?) I put four fins in the model and ran it thru my utility.

The end result is the attached *.htm file which shows a 1:1 scale printout of
the fins in my dummy model, a 1"x1" square (to check the scale of your printout) and a fin positioning template.

The length of the template is almost as long as the paper is tall, you'll probably have to print it out in landscape mode and with the margins set to be as small as possible on your printer (or you can print 2 out, line them up and tape them together.).

Note that you'll have to rename the loc3p1.htm.txt to just loc3p1.htm after you download it from TRF to see it using internet explorer.

-Kerry

View attachment loc3p1.ork

View attachment loc3p1.htm.txt
 

UhClem

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So I tried to go into excel and make the precise measurements - pi*D and all that - pretty easy stuff, came up with the four subdivisions, but then couldn't figure out how to plot the data properly.

I need to figure out a way to do this easily, as I don't want to keep coming here to ask for help. I'm working on a four fin template for a 3.1" Loc tube -normally it wouldn't matter in this size, as the main fins are always pre-slotted, but in this case, it does, as these are small detail fins that are being surface mounted. Heck a four fin template like the one above with the different tube sizes would be great at this point.
You don't need any tools more complicated than paper, straight edge, and ruler.

This is a really simple idea that I read in the very first issue of Sport Rocketry that I bought. In order to save typing I searched for a description and found it on r.m.r:

Here's a nifty way to mark fin spacings on BTs:

Wrap a piece of paper around the tube, and draw a line at the overlap
point.

Lay a ruler on the paper so that the zero mark rests on the edge of the
paper, and aome number divisible by the number of fins is exactly on the
overlap line. This will be a diagonal of some sort, but it doesn't have
to go corner-to-corner.

Mark the paper at the appropriate divisors.

Wrap it around the tube again, and transfer those marks as fin
positions.

For example, let's say I want to put 5 fins on a BT-60.

When I wrap and mark the paper, I end up with a length of just about
13cm (41.6mm * pi = 13.11cm). Now, I lay my ruler down so that the zero
point is on the edge of the paper, and then rotate it until some number
divisible by 5 is just touching the line. OK, 15cm. Now I mark at 3,
6, 9, and 12cm. Then, wrap that paper around the BT-60 again, and
transfer those marks plus the edge and voila! Five evenly-spaced fins.

It may sound complicated, but it's pretty simple if you once _see_ it
done. This technique can be used to mark off any arbitrary length into
any arbitrary number of equal divisions. Its accuracy is limited only
by the accuracy of your ruler, and by your ability to mark the paper
precisely. There's no measuring so there's no rounding error.
--
Gordon S. Hlavenka
 

NjCo

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When I wrap and mark the paper, I end up with a length of just about 13cm (41.6mm * pi = 13.11cm). Now, I lay my ruler down so that the zero point is on the edge of the paper, and then rotate it until some number divisible by 5 is just touching the line. OK, 15cm. Now I mark at 3, 6, 9, and 12cm. Then, wrap that paper around the BT-60 again, and transfer those marks plus the edge and voila! Five evenly-spaced fins.
I'm having problems visualizing this. What exactly are you rotating and where?
 

UhClem

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I'm having problems visualizing this. What exactly are you rotating and where?
The ruler.

You are basically constructing a triangle. One side is the circumference of the tube to be marked. The hypotenuse is where you put the ruler and its length is flexible so make it easily divisible by the number of fins.
 

KerryQuinn

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Hey UhClem -
I like your idea a lot. I tried it out just to make sure that I understood what you were talking about. See the attached scan.

In my example, my "wrap-around strip" was 6.45" long so, instead of trying to divide 6.45/4 and then carefully measuring and marking those distances off, I extended the end lines (see my picture) and angled my ruler diagonally across the endlines so that, measured on the angle, the distance was 8.00"
Along this diagonal, I marked dots at A1, A2 and A3, every 2.00". I then repeated this on a second diagonal line to find B1, B2 and B3.
The last step is to connect A1 to B1, A2 to B2 and A3 to B3 - and this divides the original strip into exactly 4 even sections.

If I had wanted to put 3 fins on this rocket instead, I would have angled the line a bit more so the angled distance was 9" instead of 8" and I would have put my marks at 3.00" and 6.00".

Thanks for sharing the idea.
-Kerry

wrapguide.jpg.jpg
 

UhClem

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Hey UhClem -
I like your idea a lot. I tried it out just to make sure that I understood what you were talking about. See the attached scan.

In my example, my "wrap-around strip" was 6.45" long so, instead of trying to divide 6.45/4 and then carefully measuring and marking those distances off, I extended the end lines (see my picture) and angled my ruler diagonally across the endlines so that, measured on the angle, the distance was 8.00"
Along this diagonal, I marked dots at A1, A2 and A3, every 2.00". I then repeated this on a second diagonal line to find B1, B2 and B3.
The last step is to connect A1 to B1, A2 to B2 and A3 to B3 - and this divides the original strip into exactly 4 even sections.
Not my idea but I use it every time I need to mark fin locations. Even if a guide came with the kit.

You can save yourself the trouble of constructing that second line. Just wrap the paper around the tube again and grab your piece of angle iron (or equivalent) and extend a line from each point.
 
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