7g. Match Rockets (Pyrotechnics)
Description
This article is from the Pyrotechnics FAQ, by Hans Josef Wagemueller zoz@cs.adelaide.edu.au with numerous contributions by others.
7g. Match Rockets (Pyrotechnics)
How To Build A Match Rocket
Version 1.5
7/14/95 [Slightly edited for FAQ 28JUL95]
Brett K. Carver
brett@sr.hp.com
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. :-)
Continue to:
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