Building a Lightweight Rocket

When we learned that our VBS theme for this year centered around space, we immediately decided to find a way to hang a rocket from our loft area.  We wanted to make it one of the showstoppers of our lobby design.  But, in order to make it something we could hang, it had to be lightweight.  Every design component was considered in light of the weight (and the distribution of weight) it would add to the overall feature.  

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Materials Needed for the Project

Building the Body of the Rocket

We modeled our design of the rocket off the Saturn V Rocket.  The main body of the rocket is 8′ long and about 21″ in diameter.  We wanted to have good internal structure that would not buckle when we added the top half of the rocket or the booster engines.  We started by making five 20″ foam circles.  The best way we found to do this was to use a dull pencil and ruler to draw a circle around a central point.  While we were drawing the circle, we pressed the pencil into the foam to create a groove.  We then used a small hot knife to follow the groove.  In one of the circles, draw another smaller circle with a 5″ radius in the middle and cut it out so that you are left with a donut shape.  This will be the topmost disk in the body of the rocket.  

In order to make the walls of the rocket, we scored vertical lines into a full sheet of foam.  The lines were 1.5″ apart and measured from the long edge.  Using the drywall T-square, we marked the lines with a marker.  Then, using the straight edge again, we scored the lines, being careful not to cut through the foil backing.  We found that holding the boxcutter at a slight angle so that the tip of the blade was slightly under the straight edge and the blade itself was at the correct angle for the sharpened edge made the easiest and cleanest cut.  Once the lines were scored, we carefully bent the sections back to complete the cut without going through the foil.  

Now the full sheet of foam can easily wrap around the round disks.  We put a spacer between the floor and the disk (just a box of screws that was on hand). Then we wrapped the scored sheet of foam around the disk so that it was flush with the floor all the way around.  Note that the  sheet of foam does not completely wrap the disk.  We tied some rope around the the unit where the disk was to keep tension.  We repeated the process with the other end using the donut shaped disk.  We used small 2×4 boards as the spacers for the top disk.  Now we had the scored foam sheet secured around both ends of the body.  At that point we sprayed spray foam around the disks (top and bottom) where it meets the wall and let it completely dry.  

Using a 5-gal bucket, we added a second set of disks inward.  We still used the brace under the first disk to give support to the weight of the bucket.  We positioned and glued the second set of disks the same way as the first set of disks.  When those were dry, we added one more disk in the center of the body.  We found that we did not need any support to hold that in place other than the tension from the rope tied around the out side.  Using more spray foam, we glued that into place.   

Once everything was dry, we measured the length of the gap that remained to be covered.  We cut and scored a piece of foam board to the the gap and glued it into place.  

We made the middle and top sections much the same way.  For the middle section we cut three disks that were 9.5″ in diameter.  In one of those disks we cut a 7″ whole out of the middle.  We scored a 48″x48″ square piece of foam at 1.5″ intervals.  We cut off any excess when we wrapped it around the disks.  We put one disk at the bottom (using a 2×4 spacer), the donut disk at the top, and the third disk about 6-8″ below the top disk.  We did not put the third disk in the true middle because that disk will act as a shelf to hold the top section when it is all assembled and the top section is inserted through the donut hole.  

The top section was made with three 6.5″ diameter disks and a piece of foam board that measured 20″ x 24″  (24″ being the height of the section and 20″ being the circumference).  The size of the donut hole that is cut out of the top disk is determined by the diameter of your cardboard tube.  Again, the first disk is glued to the bottom, the donut disk is glued the to top, and the third disk is glued about 6-8″ below the top disk.  

This is the top of the upper section, I didn’t have the tube with me, so I cut the hole later. 

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Covering and Collars

With the individual sections complete, we moved on to covering the foam with paper so the rocket would have a finished look.  To start, we measured lengths of the fadeless bulletin board paper to fit around the circumference of each section. We used the white side of brown paper because that is what we had on hand, but other colors should be fine.  We just didn’t want the lined to show through.  

We lined up one edge of the paper with the top edge of the foam.  Using spray adhesive as we worked, we rolled the paper onto the cylinder.  We did this for each section of rocket.  

At this point, the rocket can be assembled and covered, or you can cover individual sections for easy transport later.  Each smaller section should fit inside the hole of the section lower than it.  When you are ready to assemble the rocket, fit each of the sections into the one larger than it, then use spray foam to glue them into place.  Paint the tube black and fit it into the top of the smallest section.  You might need to brace them so that the sections stay plumb with each other.  

Making the collars (the transitions from one diameter cylinder to another) was a little finicky, but luckly, they did not have to be perfect.  We started by calculating the radius of circles we would need to draw on the foam and paper using this cone pattern calculatorNOTE:  This is a UK website, so be sure to convert your measurements to the correct units!  We drew those arcs onto the foam and cut them out.  Then, working from the middle outward (if you try to work from an end, you might find that your score lines twist), we scored the foam into strips similarly to how we wrapped the disks with the sheet of foam.  The biggest difference was, we had to start with a narrow slit at the top and gradually get wider at the bottom.  Our score lines were 1″ apart at the top and 1.5″ apart at the bottom.  However, your measurements might change,  it will depend on how high up the section you decided to make the collar (I think we used 10″ for our height).  Before gluing the cone collar to the rocket body, we used it as a guide to cut out paper with the same shape.  We purposefully went a little large so that we would have extra to work with.  We glued it into place with spray foam.  Cut off any dried spray foam before gluing the paper into place.  

Repeat the same process for the second section transition.  With the larger diameter base, we had to make the collars in two seperate pieces so it would fit on the foam board. That actually made it easier to glue into place, so that was a benefit.  

For the transition from the foam body to the cardboard tube nose, we cut a cone pattern from silver posterboard. 

Adding the Details

Whenever possible, we like to model our decorations after real-life or historical items.  So, we decided to follow the markings of the Saturn V Rocket for the Apollo 11 Mission as much as possible. 

We added the thick black stripes at the bottom and the middle of the body.  We also painted a large checkerboard marking on the large collar.  We deviated from the true rocket by painting the smaller collar and everything above it  black (except the silver posterboard) to hide the tape that would be needed and some imperfections.  

We covered each of the seams with a couple lines of black duct tape.  The duct tape made a nice transition, and  it will help protect the model from the pressure of the fishing line we will use to hang it.   

Finally, we attached red U-S-A letter and an American Flag to lower part of the rocket.  

https://history.nasa.gov/ap11ann/kippsphotos/saturn5.html

We made the booster engines from a plastic flower pot that was painted black and carpet tubed cut into 5-inch lengths also painted black.  We painted one of the circles leftover from cutting donut holes black.  We attached the flower pot to the bottom of the rocket with zip ties and spray foam.  We hot glued the carpet tubes to the black foam circle.  When the flower pot was set, we used spray foam to glue the foam circle with carpet tubes attached into the flower pot.  We filled the carpet tubes with orange cellophane.  

Hanging the Rocket

Our goal from the beginning was to hang the rocket in our lobby.  We have a loft area that overlooks the lobby, and there is a sturdy railing from whick we hung our rocket.  We used this heavy duty fishing line.  We hung the rocket from 7 anchor points on the body and 1 anchor point on the booster engines.  This was probably overkill given the strength of the fishing line, but this was our first time hanging a major decorating feature, and we didn’t want anything to go wrong, 

Using a slip knot, we tied the fishing line around the rocket body at each of the intersections (top and bottom of each foam collar), at the very bottom of the body and two locations in the large trunk, and one at the end of the boster engine. We tried to make sure that at least one of those trunk points lined up with the interior disk support.  When we had the oppotunity to do so (at the intersections and the bottom of the body) we added a few strips of black duct tape to make sure the fishing line did not roll out of place.  

If you don’t have a loft from which to hang the rocket, you could investigate the possibility of hanging it from the ceiling using more anchor points to distrubute the weigh across many points.  This would be determined by the weight of the rocket and the load capacity of your ceiling.  It would be a good idea to get the input of someone knowledgable in engineering and codes (don’t interfere with the sprinkler system, etc) to help.  

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