These tutorials show you how to build some of the components
we use on our rockets. While it may not always be possible to
reproduce these components exactly, many of the designs can be
customized based on the materials you have available.
This tutorial describes a simple parachute deployment
mechanism for multi-stage rockets or rockets with boosters. This
mechanism is activated by the staging event and
therefore only appropriate for the lower stages and boosters.
This mechanism can be used with virtually any staging mechanism.
For a parachute deployment mechanism for the upper most stage
see the side deploy mechanism.
How it works
The parachute on the lower stage is held in place by two
doors made of PET plastic. The doors are kept locked with a pin
in a similar way a hinge pin holds the two halves of a hinge
together. A wire connected to the upper stage is threaded into
the doors and holds them together. When staging occurs the wire is
pulled out and the doors are free to open and release the
Tools and Materials
- 1 x PET bottle
- Paper clip
- Tape - Craft knife
- Scissors - Long nose pliers
Wash out a PET bottle and remove the label.
You can remove the label glue with a little bit of
Cut about a 5 cm wide strip from the
section of the bottle. Discard the top and bottom of the
bottle. The width of the strip is not really important,
it just needs to be wide enough for your parachute.
Cut it into two halves. The length of
these again isn't very important and will depend on the
size of your parachute.
Straighten the strips out by bending
them backwards. This will help them spring open
when released. They don't have to be perfectly straight.
You can also reverse them so that they will spring open
Bend the end of each of the strips back about 90
degrees about 1 cm from the end.
Now bend the ends over to make a small
loop. The tighter you make this loop the better. It can
be a little tricky so take your time. Using pliers to
shape the plastic makes this a lot easier.
ends down temporarily and mark out a set of points near
the loop. Also mark out where to make the cuts in the
loops. How many cuts you have will depend on the width
of your strip, but the cuts should be about 1cm apart.
The points next to the loop should be about 5mm apart.
Straighten out a paperclip and then
heat the end over a flame. Make sure you use pliers when
you do this as the paperclip will get too hot.
Now use it to drill holes in the marked
positions near the loop. Don't make the paperclip too
hot otherwise it will make the holes too big. The
paperclip cools down quickly so you have to heat it
Now tightly weave a piece of wire
through the holes and twist the ends together. This will
secure the loops well and prevent them from coming
apart. Usually the tape itself is not strong enough to
Do this to both strips. You can remove the tape at
this point if you like.
Use a Stanley knife to cut through the
loop at the marked positions. Carefully cut away every
alternating loop. Also be careful not to slice too far
when cutting in between the loops.
When you cut out the loops make sure
they alternate on each of the strips. This allows them
to mesh together. Make sure they can come apart freely.
Attach the parachute to the lower
stage. Where you attach it will depend on your design.
Tape one strip to the bottle where you
would like to position the parachute. Use a strong piece
of tape either side of the join. The tape will act as a
hinge for the door to open.
In the photos on the left
you can see how the tape is attached to both sides of
Insert the paperclip into the loops
between the two strips to keep them aligned. Now tuck the parachute under the
to make sure it will fit snugly. You can pack the
parachute flat to make it more streamlined.
holding the parachute down with the strips, tape on the other
strip down with another piece of tape. Again add tape to
both the inside and outside of the strip.
Fit the upper stage/sustainer to the
booster and tie a piece of wire around the nozzle of the
sustainer. A piece of solid core copper telephone wire
Pack the parachute and insert it under
the two strips, and bring the loops together. Now thread
the wire from the sustainer through the loops. This will
hold the parachute in place. The wire should poke out
about an inch on the other side. Make sure the wire is
nice and smooth and that there aren't any kinks in it so
it slides out of the loops freely.
When the staging mechanism activates
and the sustainer flies off, it will pull the wire out
of the loops and the strips will spring open to release
The mechanism is now ready to fly.
Although the parachute above is fitted
to the side of the rocket, there are other places where
it can be mounted.
On the left is an example of the mechanism used on a
bigger booster. The parachute is recessed into the space
between the bottles which reduces the drag on the
We have used this design on close to 50 flights so far
with successful deploys on all of them.
Because this mechanism deploys the parachute at the
staging event and hence the rocket can be travelling fairly
fast it can be a less than ideal time to deploy a parachute.
However, the staging event will usually slow down the
lower stage considerably and by the time the parachute is
fully inflated, the stage has also slowed down considerably.
Lower stages also don't tend to fly very high, so you want
to deploy the parachute fairly soon after staging anyway.
This method can be applied to multi-staged rockets with
each successive stage pulling out the parachute on the stage