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1 week ago

ExposeExciteIgniteMay2012

• Glue gun or masking

• Glue gun or masking tape • Wooden skewer sticks • Thin metal tube used as launching guide • Sparkler (used as fuse) & lighter or nichrome resistance wire, speaker wire and 9V battery or commercial hobby model rocket igniters with battery Preparing the dowel stick: Sand the ends of the dowel stick with sand paper and smooth the sharp edges. (Figure 9.1). Mark one end as “hammer”. This is the end to which you will apply the hammer. 1. How to Make the Rocket Body The rocket design Figure 9.1 As mentioned before, our propellant is a low-impulse type and in order to create enough thrust for a lift-off, we need to ignite as much of the propellant as possible, as quick as possible. This can only be facilitated by introducing a hollow core through 80% of the propellant charge (Figure 9.2). Figure 9.2: Cross-section through rocket body We could cast or compact the propellant with a hollow core by inserting a coring tool into the body casing, but that asks for more sophisticated tooling and preparations. There is a much simpler way . . . If you have cardboard tubes available with an inner diameter of approximately 9 to 10 mm (0.4”) and the dowel fitting inside them, then you can cut them to size (" 70 mm long (2.8”)) and follow from point (e): a. The rocket body tube is prepared from ordinary white paper and bonded with white paper glue. b. Cut one sheet into three strips of paper, 70 mm wide and 297 mm in 97

70 mm length - the length of the A4 paper (Figure 9.3). (If you are using US Letter size, make the strips 2.8” wide and 11” long). Draw a line 50 mm (2”) from the one end. Each sheet thus produces three body tubes. " " A4 or US letter 50 mm Figure 9.3 c. Cover the grey area on each strip with a thin layer of white paper glue. An icy-pole / ice-cream stick is handy here. d. Place the 10 mm dowel on the glue-less end and roll the paper tightly around the dowel to form a paper tube (Figure 9.4). Finish off the outside of the tube with a layer of white glue. Put aside for 2 hours to cure. e. When the body tubes are dry, insert a plug into each tube: • Cut a small piece or approximately 2 g from the epoxy putty and mix well. Insert the mix into one end of the body tube and place this end down on a piece of waxed baking paper or smooth hard surface; • Wet the hammer-end of the dowel stick and insert it down into the body tube. Compact the putty into position by pressing down on the dowel stick (Figure 9.5). 98 Figure 9.4