Building Model Rockets

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Building model rockets weather from a kit or from scratch is not a difficult undertaking. Some of the newer kits come with all parts precut, and only have to be glued together to to fly. More traditional kits come as a bag of tubes, balsa sheets, a nosecone, and a parachute. We suggest that you start with a kit, such as one of the simpler Estes kits, to get the feel for what is involved when building rockets. After you are comfortable with building kits, you should consider designing your own.

Model rocket building is a good evening hobby as many of the steps are short but you have to let glue and paint dry before going on to the next step. Unlike plastic model airplanes and cars, a model rocket is not something that you completely build in a single sitting. If you try to work too fast, you will either end up with a mess or your rocket will not be strong and will disassemble itself at the first launch. For example, a paint job needs to dry overnight before applying the next coat. If you don't let it dry, the new coat may soften the previous coat and cause it to sag or run.

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Building Kits

Model rocket kits are probably the easiest way to get started in modelrocketry. While there are some kits that require no or little assembly before flight, you are really not in the hobby until you spend the time to build a rocket that starts as a bag of tubes, balsa sheets, and a nose cone. Part of the thrill of the hobby is spending a lot of time building that perfect rocket and then risking it all by launching it.

A simple kit consists of a paper tube, balsa, plastic, or paper fins, a nosecone, a parachute, a shock cord, an engine block, and a launch lug.
A kit of parts.

Kits may differ in whether the balsa fins are precut or not or whether the fins are balsa, paper, or plastic. If you must cut out your own fins from a balsa sheet you will have a paper pattern to use to mark the balsa for your cuts. Pay attention to the direction of the grain of the balsa. Most fin patterns have the grain direction marked. The reason for this is that you do not want the grain of the balsa to be parallel to the body tube of the rocket. Balsa breaks easily along the grain but is very strong for breaks across the grain. Because of this, you want the side of the fin that is glued to the body tube to be end grain so that the attachment to the body tube helps to strengthen the balsa and prevent splits along the grain.
Fins should be cut so that the grain of the balsa extends away from the body tube.

Lay the pattern on the balsa and draw around it with a pencil or a ball point pen. Use a ruler if necessary to get the straight edges straight. Cut the fin with a hobby knife or scalpel. Use a metal edged ruler to help you cut straight lines.

Sand the fins to shape before you glue them to the body tube. First stack the fins and pin them together with a couple of straight pins. Sand the edges of the fins bundled together like this to get the shape of the fins identical. Remove the pins and separate the fins. Sand the fins to shape, either sharpening or rounding the edges, depending on the model.

Mark the fin locations on the body tube. Most kits come with a fin marking guide. If you do not have a marking guide, wrap a strip of paper around the body tube and mark where the end crosses. Divide the parer into multiple equal sections, depending on how many fins your model has. Put the body tube in the crack of a partially open drawer or in a door frame and extend the fin marks down the side of the rocket.

Lightly sand along the fin marks where the fin attaches to the body tube. This makes the glue adhere much stronger to the body tube. Apply white glue to the edge of the fin and align it along the fin alignment marks. Hold it in place until the fin can hold itself up. Do the same for the rest of the fins. When the glue has hardened run a fillet of glue down the intersection of the fin and the body tube. Smooth it with the tip of a finger. Let the glue dry before rotating the rocket and filleting another fin. If you don't let it dry it will run down the fin when you turn it over.

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Kit Manufacturers

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Local Kit Distributers

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Designing Your Own

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Stability Criteria

Testing Stability

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Last modified on Tuesday, 31-Mar-2009 17:00:00 PDT