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  #1  
Old 12-30-2011, 04:28 PM
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Gus Gus is offline
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Default Applying Sticky-Paper Body Tube Wraps

Applying wraps to body tubes is fairly easy to do if you remember one guiding principle: Start from the middle, not from the edge!

I am going to try to make this photo essay as generic as possible, but I am going to use as my example the full tube body wrap included in the new Falcon 9 kit being sold by SpaceX.

The wrap in this kit is beautiful (pic below), very high quality paper, great detail in the printing. But the otherwise outstanding instructions suggest you line up the wrap beginning at its edge. In my experience, trying to wrap a tube starting at one edge and working your way around almost never results in a good wrap. Not only is any tiny imperfection in alignment on the starting side hugely magnified by the time you get around to the back, but rocket body tubes are fairly pliable and trying to run a wrap all the way around a tube often results in bubbles or wrinkles.

So, instead, you need to apply the wrap from its middle. That immediately cuts in half both the magnitude of any alignment error and the likeliehood of getting bubbles or wrinkles.

But how do you apply a sticky-paper wrap from its middle?
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Last edited by Gus : 12-30-2011 at 07:52 PM.
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Old 12-30-2011, 04:47 PM
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The first thing you need to do is prepare your body tube.

The body tube will need a nice straight line down its side.

The Falcon 9 kit comes with a line already drawn on the tube. This is a wonderful convenience, but I used my straight edge to double check the line just in case. Why? Because this line is critical to getting a good wrap. It must be absolutely straight from top to bottom.

Actually, the only parts of the line that really matter are the very top and very bottom. The paper wrap on the Falcon 9 kit is of such nice quality that the pencil line will not show through from the back. But when I make my own wraps on full sheet label paper (much thinner than the Falcon wrap) I always erase almost all of the pencil line on the body tube. I erase everything except ~ 1mm at the top and bottom. Otherwise, once you spray clear coat on the wrap the paper becomes somewhat translucent and the line will show through.

But as I said, on the Falcon kit not to worry. Just double check that the line is really straight.

In order to draw, or check, the line it is important to have a good tool. A door jamb won't do. You need something much straighter. The best tools I've found are aluminum angle iron from Home Depot or Loews. Very cheap and very straight. I have both a full quarter and a half-quarter (see 1st pic below) because the full quarter is too big to use on BT-5 tubes.

Use the angle iron to draw a straight line from the top to the bottom of the tube (2nd pic). Be careful not to press the angle iron too firmly on the tube as that sometimes causes the tube to deform a little resulting in a slightly off-kilter line. Once you verify that the line is straight, erase all but the very top and bottom 1mm of the line.
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Last edited by Gus : 12-30-2011 at 08:25 PM.
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Old 12-30-2011, 05:04 PM
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Next up is preparing the wrap.

I love paper wraps because they allow you to do such amazing designs. I can do way more complicated designs on my computer than I can by masking and painting. Whatever my design, I always start by creating a box with a hairline outline the appropriate size to wrap all the way around the body tube. I always try to make one edge of the wrap end alongside or under a conduit or be part of the design that has a long colored line along its edge. But most importantly, in the middle of the top and bottom of the outline boxes I put small tic-marks to indicate their middles. These are the marks that will line up with the line I draw on the body tube.

An example of what I am talking about can be seen in the pics below of a model I did of India's first satellite launcher, the SLV3. First pic below shows the completed model and the second pic shows the layout I printed onto a full sheet of label paper. Note how the layouts of both the upper and lower body tube wraps seem off center. That's because I set them up so the edge of the wrap would be under a conduit running the length of the upper and lower tubes.

More importantly, though, note the tic marks at the top and bottom of each wrap which will be used to align the wraps on the rocket.

When you design your own wraps, putting these marks on your design is very easy. When you are putting on pre-printed wraps you have to put these marks on yourself.
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Last edited by Gus : 12-30-2011 at 07:55 PM.
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Old 12-30-2011, 05:24 PM
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When using a pre-printed wrap like the one on the Falcon 9, you have to put your alignment marks on yourself. The hardest part about using wraps printed by someone else is that you never really know whether the paper was precisely aligned when the wrap was printed. Fortunately, the wraps on the Falcon 9 were beautifully done.

The top of the wrap is scored so it could be folded over to fit in the box. Although I could have just torn along the scoring and used that as my top edge, I chose instead to use a straight edge to cut off the top of the wrap right at the cut line where the wrap itself would be peeled off its backing (1st pic). I did this to be absolutely sure the top edge of the wrap was straight for my T-square to rest against.

Once I cut off that top piece, I lined up the top edge of the wrap against the cross-piece of my T-square and I put marks at the top and bottom of the wrap approximately in its middle (pics 2 & 3 below). Being absolutely in the middle of the wrap is not at all crucial, but making sure the wrap is properly aligned in the T-square is critical.

Superfluous note: I find it much easier to make very fine pencil marks if I use an official Yuri's Night commemorative pencil which has been sharpened in a rocket-shaped pencil sharpener (pics 4 & 5).
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Last edited by Gus : 12-30-2011 at 07:57 PM.
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Old 12-30-2011, 05:42 PM
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Next up is preparing the back of the wrap.

If you peel off the entire back of the wrap and try to apply it, or just peel it off half way, you are almost guaranteed to have part of the wrap stick where you don't want it. So the key is to expose just a narrow strip of sticky surface along the back of the wrap right where your tic marks are on the front side of the wrap.

Because it is a little hard to see white on white in photos, I prepared the back of the Falcon wrap with a squiggly line (pic 1). You don't have to draw the squiggly line, I only did this to better illustrate what you are going to do. At the top of that same pic, however, you will notice a tic mark. I do (and you should) put tic marks at the top and bottom of the backing at the same location they appear on the front. This shows you where you will be exposing a sticky strip.

Once you have your tic marks in place put the wrap face down on a table and put a straight edge a couple of millimeters to one side of the tic marks (2nd pic). Remove the backing from one side of the wrap using your straight edge as a surface to tear against (2nd and 3rd pics).

Once removed, replace the backing back on the wrap but repositioned so it leaves a narrow strip of adhesive exposed (pics 4 & 5). Leave maybe 1/8" of exposed adhesive. You want just enough so that you can really stick it down but not so much that its going to grab where you don't want it.
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Old 12-30-2011, 06:30 PM
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Now you are going to place your wrap on the body tube.

Align the top of your wrap so the top edge of the wrap is right at the top edge of the tube with your tic marks aligned. In the first photo below I show the top edge of the wrap slightly down from the top edge, just to illustrate aligning the marks. Honestly, when you put the top edge of the wrap at the top of the tube it usually covers up the upper tic mark. So I usually extend the tic marks on the top and bottom of the tube out onto the upper and lower edge of the tube.

While aligning the top edge I try to hold the lower edge up off the tube. Once I have the top edge aligned, I pinch that end between my thumb and forefinger and pivot the wrap so the bottom end is precisely aligned. I then pinch that end down and recheck the top. If everything is still precisely aligned, I then start in the middle of the wrap and press the exposed strip into place working my way first toward one edge, then back from the middle out to the other edge (pic 3).
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