Using Paper in Unusual Ways to
Make Unusual Rockets
by Tim Van Milligan of Apogee Components,
Paper is truly a wonderful building material
for model rockets. Did you ever really sit down and think about
its characteristics? It is light weight, strong, accepts almost
any type of glue, can be easily painted, and is both bio-degradable
When used in the construction of a rocket,
it is one of the safest materials to use, because if it hits something,
it crumples in on itself without shattering. This is the best way
to rid the kinetic energy of rocket with the least amount of damage.
The variety of paper types is immense; as
defined by its construction and material components. For example,
think of all the different types of paper products: tissue paper,
wax paper, newsprint, crepe paper, cotton rag paper, bond paper,
light cardstock, heavy cardstock, corrugated cardboard, Bristol
Board, and molded paper products; to name just a few. And papers
comes in even larger assortments of weights, colors, textures, and
finish coatings. For component materials, paper can be made from
a wide variety of organic materials: wood pulp, cotton fibers, and
the latest craze; hemp fibers.
The natural fiber paper products retain many
of the wood-like qualities. They can be cut, glued, sanded, painted,
and shaped with the same type of wood working tools. Another "wood-like"
quality is that most papers have a grain direction. To see this
for yourself, take a piece of newspaper and tear it. You'll see
that if you tear it one way, you get a fairly straight line, but
the other direction, it is very jagged. This makes it stronger in
one direction than the other; and you can use this to your advantage.
You can also see that the grain direction will make a difference
in the sharpness of a fold. If you fold perpendicular to the grain
direction, the crease isn't as sharp, and may try to straighten
And if the natural fiber-based paper products
are not enough, there is even synthetic varieties that have other
characteristics. Think of Tyvek (a polyester based paper) which
doesn't tear at all, spun woven nylon (like a Bounce fabric sheet)
which makes a great hinge material because the fibers stay springy,
and even Nomex paper that that doesn't burn. Paper is also used
in combinations with other materials too: I can think of "Foam
Core" products which are really strong and can be used to make
fins and even glider wings.
But this article is about the wood based products,
because they can be more easily used by average modelers. The characteristic
that I like about paper is that you can shape it in a variety of
ways. The best and most obvious example for rocketry is that it
is easily rolled into body tubes. You can also "roll"
it to make conical nose cones and transition sections.
There is one type of paper that is better
suited to rolled cones and transitions. It is called Bristol Board.
You can find Bristol Board in varying thicknesses at the better
artist supply stores. What makes it unique is that it is made up
of two or more layers of paper where the grain of individual layers
is placed perpendicular to each other. What this does is to make
it strong in nearly all directions, and it doesn't crease as easily.
So for rolled conic sections, like nose cones and transitions, it
yields a "better looking" part which is actually stronger
for the same weight as other types of papers.
Flat sheets, or panels of paper, can also
be used as fins on the rocket. The easiest way to do this is to
use thick cardstock. A lot of small rockets (1/4A through B) use
paper fins in this manner. A nice feature of paper fins is that
they do not chip apart from hard landings. If a paper fin is bent,
it can easily be repaired by wicking water-thin CyA glue on the
crease to increase its stiffness and strength. But since the grain
of paper isn't as strong as the grain of wood for the same weight,
for larger rockets, you typically use wood fins.
But to make these wood fins even stronger,
you can add a layer of paper to both sides! Tissue paper applied
with aircraft dope works well and adds very little weight. And at
the same time, it makes the surface smooth and can be used to colorize
the rocket. For a stronger fin, I like to use ordinary bond paper
applied with wood glue. You need to coat both the wood and the paper
with glue to assure that no air bubbles get trapped under the paper;
and you need to do both sides at the same time to lessen the warpage
of the wood.
But fairly strong paper fins can be made using
the built-up method too. This is where two skins of paper are separated
by structural spar. This method is particularly useful in making
"scale" fins - like on a Nike rocket. The fact that you
can get a sharp crease on the high point and both the leading and
trailing edges makes it easier to construct than sanding a solid
balsa wood fin. And sometimes, you don't even need a structural
spar inside the built-up fin to give it strength. I submitted an
"all paper" fin model rocket design to many newsletters
around the country. You may have seen it and even built one yourself.
Creating a cone or a transition section from
paper is pretty easy. The simple equations to begin the construction
process are found in either the book "Model Rocket Design and
Construction," or "The Handbook of Model Rocketry."
Or if you prefer, many of the rocketry software programs now have
a feature to generate patterns from dimensions you input. Once the
pattern is transferred to Bristol Board, you can begin to cut it
out using a hobby knife.
Curling the piece would be the next step in
the assembly sequence. You can do it over the edge of a table; although
this must be done carefully to get the curl in the correct direction.
The method is similar to making curly ribbons for wrapping presents;
pull down hard, and fast. The fibers will stretch slightly giving
the desired curl.
But I prefer to carefully wrap it around the
handle of a hobby knife. It is more forgiving of errors. For tight
curls, like on the point of a cone, I use a 1/8 diameter wood dowel
as a curling tool.
If you are making a pointy cone, it might
be better to make two separate cones, one out of light -weight bond
a paper, which is easier to curl, and will yield a sharper point;
the second you could construct out of a heavier weight index cardstock.
This second cone is glued inside the lightweight cone to give strength
to the piece.
Gluing the edges of the cone or shroud together
should always be done with wood or white glue. It allows you to
reposition the edges to get the correct fit before the glue dries.
It is also flexible, and can be curled itself; unlike CyA glue which
is brittle. Depending on the type of paper used, I sometimes like
to come back and saturate the paper fibers with water-thin CyA glue
(super glue). This adds incredible strength and seals the fibers
so they can be sanded down very smooth. Coated papers, such as those
with a glossy finish, don't seal well with CyA, and therefore don't
need to be sanded down later. Usually one side is un-coated and
has a dull finish; this is the side you'd apply the CyA into to
add strength. This dull side should also be oriented to the inside
of the piece.
The overlap used to aid gluing, is often an
eyesore, particularly on "scale" models. To get rid of
the seam, you have two options. First, on large diameter cones,
you can press down on the "inside" of the seam with a
fingernail. This can stretch the fibers and crease the paper so
that the overlap is less pronounced. After the cone is glued to
the rocket, you will have to come back with some filler putty and
fill any gaps. Sometimes this will deform the part, so that the
cross section isn't perfectly round, but has a point - like a teardrop.
You may need to reform it before gluing it to any tubes so it is
On cones 18mm dia and smaller, that method
doesn't work well, so you should leave off the extra glue tab when
you cut out the pattern. Use a separate piece of paper, and glue
it over the joint between the two inside edges being joined. This
should leave a very thin join line on the outside of the part which
can be filled later with putty. The drawback is that you don't have
the ability to reposition the part while the glue dries, so your
pattern has to be fairly exact when you cut it out. You can also
use this method on large cones too.
Cones or truncated cones made using this method
can be purely decorative too. I like to make "simulated"
rocket nozzles that add a lot of pizzazz to most models.
"Molded paper products" is
pretty much the only other way to make complex and compound curves
out of paper. You've probably seen molded paper in the form of egg
cartons at the supermarket. The are formed by making a thick water
slurry of paper fibers and pouring it into a two part mold. The
mold halves are brought together under a lot of pressure which squeezes
the water out of the fibers. Typically, one side of the mold has
a mesh surface which allows the water to escape. This makes one
side fairly smooth, and gives the other side a rough texture. The
part is then removed from the mold and allowed to dry. Big parts
with thin wall thicknesses can be made this way. I've seen very
large plant pots made out of this method.
I think we've all made molded paper products
as juveniles in the form of spit wads! But for rocketry, molding
paper hasn't really caught on due to the intensive set-up required
to make molds. A simpler way may be to use a papier-mache set-up.
I think a neat use of molded paper would be to make a shroud for
a Delta Clipper type model that is a big flying shroud with a rounded
nose. It could be made both light and strong with this method.
Flat sheets of paper can be folded into very
complex shapes; which is where the title "Rocket Origami"
comes from. Cutting, folding, and gluing paper is an art-form that
I think can be taught to most modelers. But before this can happen,
you have to have a desire or need for the shaped part. So what types
of items can be made?
As mentioned before, the obvious ones are
tubes, nose cones, transition sections, and simulated nozzles. If
you look in some old rocketry catalogs, you can find some others
too: cockpits, and simulated jet engine inlet ducts. The variation
of designs is only limited by the imagination of the builder.
Making 3-D parts this way using flat sheet
stock is called "pattern development." The easiest pattern
development to make is the cube. If you unfold a corrugated box,
you'll see how this method works.
What makes pattern development challenging
and fun is making two different 3-D objects mate to each other.
This is where textbooks that teach engineering-type "drafting"
come into play. If you are really interested in doing complex rocket
origami, the books will show you "step-by-step" how this
For a simple start, I'd suggest designing
a paper cockpit. Basically you could start with a cube and see how
to mate it to a tube. If you leave one end open, now your cockpit
becomes a jet engine intake duct. Then you could start changing
the cockpit or intake duct by making one side an angled piece (now
the cube becomes a prism). By continuing to stretch the shape of
the prism, you could turn the cockpit into a long shroud -- like
the conformal tanks on a NASA X-15 rocket plane.
A variation of the conical transition piece
would one that transitions from a circular tube to a rectangular
or triangular tube. I first used this method on a rotaroc style
helicopter; I needed a triangular tube to give me a flat area to
mount the hinges for the blades.
You can add even more challenge to the pattern
development process by mating two curved pieces together. I'd start
by changing the simple right angle nose cone to a "oblique"
cone; where the point is not over the center of the cone base, but
off to one side. This could give you a nose cone for a Ariane or
Proton scale model.
For modelers who want to go to the extreme,
how about trying to mate two tubes together at an odd angle? This
could be used to duct the ejection charges of side pod motors into
the core tube of a model. You could use the same piece to create
another type of simulated jet intake duct, but with a circular opening.
I've used this same method to make tube fins that jutted out into
the airstream and that looked like thick dowels.
And other combinations are possible too. I've
made "cone fins" and transitions that make it possible
to mate together a cluster of two tubes down to one single tube.
To date, the most complex part I've made is an oblique cone which
mates with two tubes; that allows ejection charge gases to vent
into the core tube from a pod tube. This is one method that could
be used for the NAR 6-C cluster altitude competition model. A copy
of that very complex pattern has been printed in many club newsletters.
For modelers that would like to 'cheat' and
see what other finished parts might look like, you can purchase
Apogee's "Designer's Resource Pak" which includes all
of these different pieces listed above. A nice feature of the parts
is that with a photocopy machine, you can change their size so they
even can be used on big model rockets!
Finally, you can even make entire rockets
out of large shaped shrouds. The classic examples are some of the
kits produced by Quest. The "Space Clipper" and their
version of the NASP are excellent examples of the types of rockets
that we can all create ourselves. The added advantage is that all
types of surface decorations (panel lines, heat protection tiles,
insignia, etc.) can be printed on the outside of the paper, so that
the finished model looks really complex, even though it is simple.
Oh... I just remembered the most important
characteristic of paper that makes it a great choice for rocket
builders. It is cheap! Most times, it is even FREE! So if you are
limited by your rocketry budget, it is the "best" material
to use for construction. So get to know it; find out its advantages,
its limitations, and ways to shape it. Then you'll develop a great
appreciation of its many great qualities.
For further information on Apogee's "Designer's
Resource Pak" or any other Apogee products, you can download
a catalog from the Apogee web site or send $1 for a catalog to:
Tim Van Milligan
Apogee Components, Inc.
630 Elkton Dr.
Colorado Springs, CO 80907-3514