7g. Match Rockets

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How To Build A Match Rocket V

Disclaimer: Please notice that the title is not "How To Build THE Match Rocket". This describes how I built match rockets and represents only one method of construction. Others will have different/better ideas. This should be enough to get one started. Warning: Improper construction of match rockets can cause them to explode KILLING YOU INSTANTLY; Improper firing of match rockets can cause them to penetrate your body KILLING YOU INSTANTLY. (well, probably not, but be careful anyway). Definition: Basically, a match rocket is a paper match with something wrapped over the match-head to form a combustion chamber and focus the flow of escaping gas. The match is then heated until it ignites and the escaping gases cause it to take off. Parts: You'll need the following: a book of paper matches aluminum foil cellophane tape (i.e. Scotch tape) two sewing needles scissors Constructions: This roughly how I built them... 1. Remove a match from the book. Trim off the end to remove the frayed edges from where it was ripped out. 2. Use about 1 square inch of foil and 'wrap' it around the head of the match extending between 1/4 and 1/2 inch past the head. I left 'wrap' vague since there a many ways to do it. The goals are to: a) keep weight down, b) get several layers of foil around the match head, and c) keep things neat and clean. 3. [optional] I had a lot of trouble with blow-out (the force of combustion tearing a hole in the foil), so I started wrapping the foil with a few layers of cellophane tape. It seemed to solve my blow-out problems without adding as much weight as additional foil did. 4. Add two exhaust ports, one down each side of the match. This can be done two ways: a) after step #3, push a sewing needle along the match-stick, under the foil, up to the match-head, or b) do steps #2 and #3 with the needles already in place. In either case the important thing is to get a small well-formed port. I used the smallest sewing needles I could find (the head of a regular pin caused it not to lay flat creating poor ports). In addition, I'd run my finger-nail along the side of the needle to force the foil down so that I'd have a nice clean tube rather than just a crude gap between the match-stick and the foil. I use two needles because with only one I'd always end up damaging one port while creating the other. Obviously, remove the needles when done. Example: What follows is ONE way to wrap the foil around the match head (step #2 above). This is the basic method I used, but I'm sure it can be improved: 1. Start with a one inch square piece of foil: ########## ########## foil -> ########## ########## ########## 2. Fold in half (it's now 1" x 1/2"): ########## foil -> ########## ########## 3. Fold in half again over the match head (it's now 1/2" x 1/2" with the match head in the middle (the head is now covered with a double layer of foil): ##### foil -> #####======= <- match stick ##### 4. Sort of fold/wrap the excess foil around the match as neatly as possible: After wrapping one side: foil -> #####======= <- match stick ##### After wrapping the other side: foil -> #####======= <- match stick 5. Move on to step #3 above (optional tape). Firing: Put the completed rocket in a launcher. It is often suggested that one use a bent paper-clip as a launcher. Don't waste your time. I used a short piece of 1/4 inch copper tube mounted to a hinge. The launch angle was adjustable by turning a screw. The tube was short enought that the match-head just extended enough to apply heat. The back of the tube was blocked off. Besides the obvious ease of launch-angle adjustment, the smooth tube reduced friction or hang-ups when firing, and the blocked off tube produced some back-pressure that I think helped produce higher launch velocities. Anyway, once in the launcher, aim it, and heat the match-head until it ignites. A lighter works better than a match for this as it takes a while for ignition and sometime the match would burn out first. Distances: I saved my record-breaking matches writing the distances on them. Launches inside the house became limited by the ceiling and the far wall. The longest inside launch I got (hitting the far wall) was: 29' 6" Outside shots were not so limited. The longest outside launch was: 44' 8" So, there are some target numbers to shoot for... :-) Fine-tuning: The point of building match-rockets is not to simply 'learn how to do it', but to get started and fine-tune the rockets to improve distance. Construction materials, construction techniques, launcher design, launch angle, and many other things all come into play at getting a long-distance flight. Experiment. Have fun! Things that didn't work: The following are things I tried that didn't improve my flight distance. 1. Wooden matches - they were too heavy. 2. Using two or more matches - too heavy and I couldn't get a good seal on the combustion chamber. 3. Adding extra match-heads - adding extra 'fuel' presented two problems: a) I had trouble getting a nice tight wrap of the foil with the extra material in there, b) if I did get a good one built, it would 'blow-out' at launch (adding more foil just seemed to make it too heavy). I had my best results with simple one-head rockets so I stopped trying for more fuel. Final caution: Don't play with matches. :-)

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