Well, a parachute can be made out of pretty much anything that is
lightweight and doesn't allow air to pass through. A plastic bag (like
the ones they use at the supermarket) would probably be a pretty good
material to use. You would want to cut out a circle of plastic about 12
to 14 inches in diameter, and fasten strings to points around the edge
of the circle using something that would hold them there securely.
Attach these strings to your rocket, and you now have a parachute!
As far as getting the parachute to come out of the rocket at the
appropriate time, that isn't very easy. My best advice would to buy a
model rocket kit, available at many toy stores or hobby stores. Not
only do these kits have a parachute included, but they also have a
system that gets the parachute out of the rocket.
The parachute system works like this: When the "thrust" stage of
the rocket engine has burned up, a "timer" stage ignites, which burns
for 3 or 4 seconds. After that, a small explosive charge is ignited,
which doesn't blow up the rocket, but instead pushes out the nosecone
of the rocket, allowing the parachute to soften its landing. A VERY
important part of this is having someting inside the rocket to absorb
the blast so the parachute doesn't burn. It's sold (and sometimes
included) in most kits as "recovery wadding", and it makes sure that
the parachute is protected from the explosive charge.
I used to be into model rocketry myself, and this is how it worked back when I did it. I hope this helps!
(republished on 07/30/06)