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  #1  
Old 09-28-2012, 03:46 PM
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Default Estes "Renegade" instructions

I just started building an Estes "Renegade" kit, which is basically a BT60 two stage bird with a lot of goobley goop fins on the booster. I made an exact tracing of the fin locater wrap. When wrapped around the body tube the match lines would not match, no matter how tightly I wrapped it. The wrap was about 3/64" short of the full circumfrence.

So I made my own wrap and checked it against the original. Again, an error of about 3/64".

I think that Estes must have used the specified diameter (1.637") multiplied by Pi (3.142) and got 5.143454". I think they forgot to include the thickness of the paper wrap (0.004") in their calculations. The paper wrap would increase the actual outside diameter from 1.637" to 1.645" and therefore the circumfrence from 5.143454" to 5.16859", for a difference of 0.025136". (1/32" = 0.03125")

Has anyone else experienced a similar problem on this or other Estes templates?

Last edited by tmacklin : 09-28-2012 at 05:51 PM.
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  #2  
Old 09-28-2012, 03:58 PM
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I've had fin guides that were too small to fit without a slight gap on Estes kits ever since the 70's. I only made my own when the gap was pretty bad.
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  #3  
Old 09-28-2012, 04:21 PM
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Quote:
Originally Posted by tbzep
I've had fin guides that were too small to fit without a slight gap on Estes kits ever since the 70's. I only made my own when the gap was pretty bad.


I never noticed this until now, and probably would never have noticed it except for the fact that there are two fins at 60 degrees off the main 120 degree increment that should have lined up opposite each other (180 degrees) and they wouldn't if I'd stuck with the stock
"cut out" spacing guide.

It's no big deal unless one is striving for perfection. Since most airframes are either 3 or 4 fin configurations, I'll just make my own spacing wraps and save them for future builds.
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  #4  
Old 09-28-2012, 05:08 PM
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What I've done when that happens (which is most of the time) is to mark the fin locations and launch lug locations using the wrap. Then I flip it the wrap over and slide it the other way over the tube. I then line up the launch-lug mark with the line I drew for the launch lug. Then I draw the fin lines again. This results in two lines for each fin that are close to each other. I center each fin between the two lines.

-- Roger
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  #5  
Old 10-01-2012, 10:34 AM
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Quote:
Originally Posted by jadebox
What I've done when that happens (which is most of the time) is to mark the fin locations and launch lug locations using the wrap. Then I flip it the wrap over and slide it the other way over the tube. I then line up the launch-lug mark with the line I drew for the launch lug. Then I draw the fin lines again. This results in two lines for each fin that are close to each other. I center each fin between the two lines.

-- Roger



I like your solution.
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Old 10-01-2012, 11:45 PM
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I was actually going to write an article about this and submit it to th e peak of flight ezine, but figured everyone knew about this.

You can make your own body tube wrapping guides in less than five minutes and all you need is paper, pencil, ruler and a compass.

1) cut a strip of paper about an inch to two inches wide and long enough to wrap around the body tube with a little excess.

2) wrap the paper strip around the tube and overlap it to make sure the paper is perpendicular to the longitudinal axis .

3) draw a line across the paper strip using the end of the strip as a guide.

4) unwrap the strip and measure from the end of the strip used to draw the guide to the line drawn.

5) divide this distance by three for a three fin equally spaced fin rocket or four for a four finned rocket. for odd angled fins you will need to compute some percentages and I won't get into that here.

6) Use the compass (or if you have then, dividers) to mark off the distances along the strip of paper you have. Start at the end and measure back along the long edge toward your line.

7) Observe the difference between your last compass mark and the line drawn across the strip. adjust the compass larger or smaller to correct for the error. (Remember you are correcting the compass for 1/3 of the error for three fins.)

8) repeat steps 6 & 7 until your last compass mark comes out right on the original line you drew across the paper strip.

9 re-wrap the strip around the body tube and mark the fin locations as usual. Make sure when the strip is re-wrapped that the end of the strip lines up again with your original line.

That's it in a nutshell. If you can't follow or understand the procedure, you will have to wait till I get off my lazy rear and write the article with pictures.

Not only can printing processes change the distance between the lines, but other climate issues (humidity being the most common cause) can also make a big difference.
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  #7  
Old 10-02-2012, 02:20 AM
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Quote:
Originally Posted by bernomatic
You can make your own body tube wrapping guides in less than five minutes and all you need is paper, pencil, ruler and a compass.



I'll see your less than five minutes and raise you less than one.

All you need is a pencil or pen, a ruler, your favorite means of drawing a straight line on your body tube, whether a piece of angle iron, door jamb or drawer and the key item, a sheet of paper with two perpendicular edges; a standard piece of printer paper works fine.

Wrap the paper around your body tube so that one of the perpendicular edges follows the circumference of the tube. Mark where it overlaps.

Remove the paper and put it down on your table. With your ruler, draw a line from the mark you have made at the overlap to the other perpendicular edge so that the line is x units long, where X in the number of fins you will be using. The size of the unit is not critical, but I find it convenient to pick it such that the line is around a 45 degree angle across the perpendicular corner.

Mark the diagonal line at each of the units. Wrap the paper back around the tube the way you had it in the first step and tape it into place.

Draw a line along the length of the body tube at each unit mark you made on that diagonal line.

Now you have x lines on the tube evenly spaced.

If you want a launch lug line between two fins, it is trivial to halve a segment by folding the paper in half to bisect one of the units of the diagonal.

I did not come up with this; David Schultz (UhClem) told me this one.


Bill
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  #8  
Old 10-02-2012, 02:21 AM
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Then there's the old draftsman's trick...

wrap a strip of paper around the tube and mark where it overlaps... draw a little arrow pointing back the direction that the wrap started so you measure the correct direction...

I do this on BOTH edges of the paper strip... that way you establish a line SQUARE to the edge of the paper by connecting the two edge markings with a ruler, once you've unwrapped it from the tube.

Lay the paper out flat, connect the two hash marks at the overlap using a ruler and pencil to draw a line. Measure the circumference of the tube in inches or millimeters (I usually prefer millimeters because it's a larger number and smaller, more even increment that's easier to work with in this instance, but it's entirely up to you...

Once you have this measured, divide by the number of fins you're putting on, if you want them EVENLY SPACED... (which 99% of rockets are made this way). You'll probably come out with a number and a fraction or decimal "leftover" since rarely do tubes come out with even multiples when divided by 3 or 4, the most typical number of fins...

Now, you CAN measure out the fraction of a millimeter and call it good, or you can do it more accurately and easier with the draftsman's trick... choose a number GREATER than the cirumference you measured, which IS an even multiple of the number of fins you're putting on... say your tube measured 7.5 inches around, and you want to put 4 fins on it... 8 is a good number, because it's greater than 7.5 and an even multiple of four (2). If you were doing three fins, 9 would be a good choice-- it's greater than 7.5 and an even multiple of 3 (3).

Now, put the end point of the ruler on the corner of the paper that was overlapped, and then TILT the ruler across the paper until the "8" (for four fins) or "9" (for three fins) is on the overlap square line you drew earlier. Ensure both the start point and the desired number line are EXACTLY on the beginning point and square circumference line. Draw a line down the length of the ruler at an angle across the paper from the edge to the square line. Make a tick mark at the 2, 4, and 6 inch marks for 4 fins, or the 3 and 6 inch marks for 3 fins... or whatever multiple of the original fin number you chose, depending on your tube size...

Flip the paper and repeat... this will establish two precisely parallel lines, each of equal length (the multiple of the fin number you chose earlier) and ensure the marks are square to the paper and each other.

Connect the hash marks on the two lines with each other using the ruler, and extend them to the top and bottom edge of the paper strip... this will give you precisely evenly spaced fin lines to mark the tube with, at the appropriate fractions, without all the busy measuring down in the fractions and decimals...

Wrap the paper around the tube again. Mark the fin lines onto the tube. One fin will fall on the overlap/edge of the paper where it overlaps itself... the others will be equally spaced...

To cut an accurate strip of paper for this method, just cut a strip off the edge of a sheet of printer paper by carefully aligning your ruler with the edge of the sheet, and then running a hobby knife down the back edge of the ruler... instant square, even strip of paper ready to go...

Works like a champ on ANY tube, ANY size, and ANY number of fins...

Later! OL JR
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  #9  
Old 10-03-2012, 01:41 AM
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Quote:
Originally Posted by luke strawwalker
Then there's the old draftsman's trick...
Later! OL JR


If you're going to use the old draftsman's trick, you really need to use the sliding triangles when doing it the way you mentioned.

The best part of what OL and Bill have described is that it doesn't rely on pre-printed strips which may not exactly work due to myriad ways the strip and the tube may be different from each other.

However that all being said, I have never seen a strip from a manufacturer's instructions that was so terrible that it couldn't be used at all.
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  #10  
Old 10-03-2012, 01:52 AM
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Quote:
Originally Posted by bernomatic
If you're going to use the old draftsman's trick, you really need to use the sliding triangles when doing it the way you mentioned.

The best part of what OL and Bill have described is that it doesn't rely on pre-printed strips which may not exactly work due to myriad ways the strip and the tube may be different from each other.

However that all being said, I have never seen a strip from a manufacturer's instructions that was so terrible that it couldn't be used at all.


Meh... works for me...

Later! OL JR
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