Space Derby Planning Guide 2
The Space Derby is
similar to the
Pinewood Derby or Raingutter Regatta except that the models are
'rockets' -- propeller-driven and powered by two or three rubber bands
travel along a heavy monofilament fishing line. The rockets are carved
boys, with the guidance of their parents or other family members. Space
Derby kits with building instructions are available at the Scout Shop.
Use the design in
the Cub Scout Leader How-To Book, pages 9-44 through 9-47, ISBN
0-8395-3832-4. Do not deviate from the measurements. The 4 lane
design fits nicely in a large van (or any vehicle that can handle a 4x8 sheet
of plywood). It is also nice to load the starting gate with 4 space derbies.
are NOT included: The upright dowels (to stabilize the space derby in the
starting gate) should be 3 inches tall and spaced about 2 inches apart.
monofilament fishing line through each eye on the gates back and forth. Do
not make separate lengths of line for each lane. This makes it easier
to make all the lanes the same tension by simply pulling the gates away from
each other. Weigh down the starting and ending gates with sand bags.
Tie several (5)
pieces of cloth at and just beyond the finish line. This acts as a
bumper stop without damaging the propellers. Carefully look at the
illustration in the Cub Scout Leader How-To Book.
Getting Things Started
100 turns, 3
rubber bands for a 45 foot run. To reduce rubber band breakage, do not wind
more than 100 turns.
There are many alternative
non-rocket designs such as: cruise missiles, boats (Titanic is always
popular), planes, jets, etc.
plastic straw MUST go over the hook (not just the shaft as the drawing
in the space derby kit illustrates) This is where the rubber bands will hook
on - the wire hook will cut the rubber bands without the plastic straw
rubber bands (spray silicon, ethylene glycol, castor oil, ...)! Stretch
them numerous times before loading, hand wind the bands numerous times before
races (20 winds, then 40 winds, then 60, 80, 100) -- this helps relax the
elastic properties of the band and makes it more pliable and durable (this is
exactly why the clowns stretch the balloons before blowing them up!).
The plastic dowel
at the rear of the space derby to hold the rubber bands MUST be kept
from rotating (groove out the back so the dowel can sit in it!) - do not glue
Do not glue the
front nose/propeller assembly into the front of the space derby. It is
pulled off to re-load new rubber bands!
Do not glue the
back dowel onto the rocket. It is pulled off to re-load new rubber
should have the rounded shaft-end pointing into (touching) the space derby
(this makes the bending of the wire easier and it reduces friction).
Hints - From a Father and Son
Lighter is definitely
There is a limited amount of force and
energy in two (2) rubber bands wound 100 times so minimizing the mass of the
unit can only help. We've seen a number of winners and the shapes of those
winners differ dramatically. One thing in common with both of them is their
weight. Both were very light and well balanced. The key is making it light
without removing so much material that the winding of the rubber bands actually
splits the ship in two or causes serious cracking. That's happened to potential
winners for both of the last two years and the kids are pretty upset when it
The shape is not the
We have seen a number of different shapes
and the winners were very different. One was cigar-like while the other was
more like a Klingon® vessel (from Star Trek©). A lot of shuttle look-a-likes
have been used and various other configurations. As long as the vehicle is
symmetrical and light then it seems to perform well.
No glue on the propeller
Never use glue on the propeller assembly.
Other than the fact that you may slip a bit and get some glue on the prop
itself or on the bushing underneath, if you break a rubber band you have to be
able to remove the propeller. During the Space Derby this year we had a number
of problems including the rubber bands breaking during the winding and the
actual propeller breaking. If that happened to a space vehicle where the
assembly were glued in place it would have much more difficult to replace.
Make sure the propeller
is on correctly.
Several Space vehicles this year had the
propellers on backwards. When looking at the hub (center) of the propeller
closely, there will be rounded end and a rougher end that is not even. The
rounded end goes towards the rocket ship and should be touching the small metal
bushing. The rougher end has a little protrusion that is designed to catch the
wire when it is bent over. Which leads to the next tip...
Don't cut the bent over
wire too short.
We were guilty of this one. In the
attempt to be neat I cut it too short and then during the winding, the
propeller can slip and spin around. Leave a little more than you think is
necessary and you should be fine. Just bend it over to form an inverted 'U',
with plenty to grab the prop, and then there should be no trouble.
Make sure the red
plastic liner covers the entire hook.
The red plastic sleeve that slips over
the metal hook (on the inside of the propeller assembly) MUST be put in place.
That is there to prevent the metal hook from cutting through the rubber bands
during the winding. It sometimes takes a little effort to pull it all the way
on but it can be done. You can always grab the end of the wire with some pliers
and work it on slowly, but make sure it goes all the way to the end of the
Don't glue in the tail
unit that holds the rubber bands in place.
Basically for the same reason. The
rubbers bands can't be altered in any way without disassembling the unit. This
actually happened to one Scout's vehicles and repairs were difficult.
The tail unit needs
notches to prevent spinning.
After you are all done with your space
ship make sure there are two depressions, of 'V's cut into the tail to prevent
the end unit from spinning during the winding or once the rubber bands start to
unwind. It may wind up okay but when the pressure is released slightly it may
start to spin. If you cut them to deep you will be essentially shortening the
spaceship and decreasing the pull on the rubber bands. It's more of a trial and
error type thing. Start shallow and increase as needed.
Various fin/wing sizes
and configurations work.
We personally haven't had a lot of luck
in this department - I guess I have to read up on my aerodynamics. What I've
seen is winners with small fins all over the ship and winners with just two big
wings and a tail like the space shuttle. The bigger wings seem to cause less
spinning when the ship is released for a more level flight, while the smaller
fins seem to allow the ship to carry its speed a bit better. The bottom line is
they both seem to work if everything else is done right. My personal opinion is
that the bigger wings seem a bit better but you'll have to figure that one out
on your own. Why we keep using the small fins is a mystery to me.
Remember, it's only a game and this is
How to Run the Space Derby
and Operating Rockets
Space Derby Events
- Plan an opening ceremony, such as a ribbon-cutting.
- Handle all aspects of awards (decorated platform, signs,
tables, trophies, ribbons, medals, etc.)
- Plan for crowd control.
- String pennants for decoration.
- Secure public-address system or bull horns, if needed.
- Check entries for use of official materials.
- Mark a number on each rocket.
- Act as judges for craftsmanship award and other special
awards. Report winners to program committee.
- Enter rocket numbers and boys' name on a preliminary heat
- List heat winners on semifinal sheets.
- Determine final standing of each rocket and report results
to program committee for presentation of awards.
Flight Operations Team
- Have two starters with green flags.
- Have two judges with checkered flags.
- Have two gatekeepers to line up boys.
- Set up the space derby raceway.
- Report preliminary winners and final winners to
Constructing and Operating Rockets
The official space derby kit includes all necessary materials and
instructions for building. Decorate the rocket with bright colors. Apply decals
furnished in the kit.
Tips for rocket builders:
- Reduce air friction or "drag" by making all
surfaces as smooth as possible. A blunt, rounded nose causes less drag
than a sharp nose. A good design has all leading edges rounded and
trailing edges tapered to reduce the drag.
- Rubber bands should be lubricated before the race. They
are the "motor" and must be strong and flexible.
- Use a sharp knife for cutting the grooves for the hanger
fitting and fins. A dull knife will crush and splinter the balsa wood.
- When you start to carve, remember that the end with the
small hose is the rocket nose.
- A potato peeler is good for carving the shape.
- To help increase the rocket's spped reduce the wall
thikcness to a minimum of 1/8 inch. Do not weaken the area around the
hanger (carrier) or carve away the nose button circle.
- Do not apply too much apint to the outside unless you sand
between each coat.
- Be careful not to get glue on the plastic carrier,
especially in the holes through which the monofilament line runs. Glue can
interfere with smooth operation.
- Make the propeller shaft as short as possible by bending
it close to the prop. Cut off the excess wire with wire cutters.
- Test the rocket's balance by hanging it from a string
through the hole of the hanger fitting. If the rocket is nose-heavy, carve
or sand a little wood off of the end. It it's tail-heavy, remove wood from
the tail area.
Dens may wish to secure a 100-foot length of 50-pound monofilament fishing
line for test runs in the backyard before the derby. Tie the line to a tree or
post and string the rocket carrier on it. Tie the other end to a tree about 100
feet away. Make the line as tight as possible.
Sample Space Derby Program
- 7:00 Inspection and registration of rockets.
- 7:30 Opening ceremony.
- 7:45 Cut ribbon and start heats. Award ribbons and
other prizes to heat winners during the running of the derby.
- 8:30 Recognition ceremony. Recognize champions;
then make advancement awards.
- 8:45 Closing ceremony.
Sample Space Derby Rules
all rockets must pass the following inspection to qualify for the race:
- Only basic materials supplied in the kit may be used.
- The rocket body may be no longer than 7 inches, not
including the propeller and fins.
- There are no restrictions on the weight or design of the
Space Derby Procedure
- Every boy brings his rocket to the inspection table to
have his entry checked and numbered.
- Then he goes to the registration table where his name and
rocket's number are entered on a heat sheet.
- Contestants report to the gatekeepers, who line them up in
the order in which they will compete. At this point, each boy starts to
wind the rubber-band motor of his ship.
- As his name is called, the boy hooks his rocket on the
guideline assigned to him, centering the rocket between the vertical
dowels and locking the propeller behind the horizontal dowel on the
- The gatekeeper starts the countdown and fires at zero by
lifting the starting gate frame, which releases the rockets.
- The race is run in heats, up to four contestants at a
time. Each boy gets to try at least twice instead of being eliminated from
competition from after the first race. For example, in a six-boy den, try
heats of three boys each. The winner of each heat goes into the den
finals. Then race the other four again with the winner competing with the
other heat winners for the den championship and entry into the pack
- The winner takes his rocket to the registration table for
recording, then to the awards platform for recognition. He then returns to
the spectator area to wait until his name is called again.
- Run as many quarter-final and semifinal heats a necessary
to determine the contestants for the final.
- As ships are eliminated, make sure the contestants are
applauded for their efforts.
Tips for Preparing for Flight
- Lubricate the rubber bands before the derby. This prolongs
the bands' life and power and will help reduce the possibility of breaking
during the competition. They can be soaked overnight in castor oil. Or mix
two parts green soap, one part glycerin, and one part water and rub the
mixture on the rubber band about an hour before racing.
- Have extra boxes of rubber bands on hand. Remember, it
takes three rubber bands to fly each ship properly.
- Experienced rocket racers "warm up" their space
ships by gradually winding the rubber band motor to its full
capacity-first 50 turns, then 100, then 200, etc. Release the propeller
between each winding.
- A small hand drill is excellent for winding rubber bands.
It also helps speed up the event. Check the ratio of the drill by making
one revolution of the crank handle and cout the number of times the chuck
turns. Most drills average a one-to-four ratio, thus it would take 40
turns of the crank to give 160 winds on the rubber-band motor. When using
the hand drill winder, it's best for one person to hold the rocket and
propeller while another stretches the bands about 12 to 15 inches beyond
the rocket tail and turns the rubber bands, he gradually shortens the
distance between him and the rocket.
- For a more evenly matched race, wind all rocket motors the
same number of turns. For 100-foot launch lines, 150 to 170 winds should
Special Space Derby Events
- Speed. First rocket to reach the finish line wins.
- Endurance. Last rocket to reach the finish line
- Relay. Use two or more guidelines. Boys form teams of
twos. The first boy releases his rocket, and as soon as it reaches the
other end of the line, his teammate removes it, rewinds it, puts it back
on the guideline, and releases it. The first rocket to return wins.
- Altitude. String a guideline which is about 12
inches from the ground at the starting line and 5 feet at the finsh line.
Gradually, raise the high end of the line until all rockets have been
eliminated. The one which climbed the highest wins.
- Just For Fun. Have rockets break balloons at the
finsh line. Do this by inserting several straight pins through a piece of
cardboard. suspend the cardboard from the finish line and place a balloon
in front of the pins. The rocket will drive the balloon into the pins.
Space Derby Rocket Assembly Tips
- Glue the two halves of the rocket body together, shape
with a potato peeler, then sand. Carefully align and glue the
two halves of the rocket body with Elmer's glue, or something similar.
After the glue dries for 15 minutes, shape the body with a potato-peeler until
it looks roughly like a rocket. Then sand it into its final shape with
medium grit sandpaper. Wrap sandpaper around the body, holding it with one
hand while you twist the fuselage with your other hand. Design tips: Fast
rockets are smooth, aerodynamically shaped, and lightweight. Make the
shell of the rocket thin, but thick enough to hold the hanger that will be
attached in step 4 and thick enough to support the pressure of a tightly
wound rubber band.
- Cut notches for the plastic dowel. The rubber bands
will slip without these notches. Do NOT glue the dowel onto the
body! The dowel will be held in the notches by the rubber bands - and must
be removable so that broken rubber bands can be replaced.
- Hold the body upright on a nail when you paint. Tap
a long nail a few millimeters into a block of wood. Set the block on a
newspaper-covered floor or table with the nail pointing straight up. Slide
the rocket onto the nail, inserting the nail into the rocket’s hollow
center. Paint with a couple coats of primer, sanding lightly with fine
sandpaper after each coat. Next spray on a topcoat. Don't use too much
paint, you want a light rocket.
- (TAKE SPECIAL CARE WITH THIS STEP!) Attach the hanger,
making sure that the rounded end points forward and that the hanger
doesn't protrude into the rocket’s hollow center chamber. Glue it on with
generous amounts of glue. Cut a grove for the hanger in the top-center
of the rocket body. This 1" grove should be centered, 3" from
the front and 3" from the rear of the body. Press the hanger into
this groove, rounded end forward. The hanger must not protrude into the
hollow chamber in the center of the body or it will interfere with the rubber
band. The hanger must be firmly glued in place or it may detach during
launch with disastrous consequence. Use a generous amount of glue to affix
the hanger to the rocket body and allow the glue to dry overnight; a
couple hours dry time may not be enough for Elmer's glue. Warning:
the rocket pictured on the front of the space derby kit box has an
incorrectly attached hanger. Don’t use it as a guide.
hanger’s rounded end must point forward.
hanger must not protrude into the rubber-band chamber.
hanger must be very firmly glued on.
- Cut and attach the fins. Shape the fins with
scissors, then cut slits in the rocket and press the fins into the slits.
Glue in place. Design tip: some claim that the fins should be angled
upward very slightly. In theory this lifts the rocket slightly off
the line during flight, reducing friction.
- Trim and balance the propeller. Sand loose pieces
of plastic from the propeller. If the propeller is unbalanced, one side
will swing to the floor when it is placed in a horizontal position. Sand
the edges of the propeller to balance it.
- Don't tighten the cable tie. The rubber bands have
already been attached to the dowel and a loop made from a cable tie has
been added. Well use this loop to wind rockets at the races. Don't tighten
it. (Don't panic. This pre-assembly and the cable-tie are
NOT part of the standard kit. Some packs/troops add this before kits
are handed out.)
- Pull rubber bands through with a wire hook. You can
make a hook from coat hanger wire.
- Fine tune. Test the rocket's balance. Hold it
lightly by the hanger with your fingers. If the rocket is nose-heavy,
carve or sand a little wood off that end. If it's tail-heavy, remove wood
from the tail area or from the fins. You may be able to unobtrusively take
wood from the rocket's hollow center chamber. Some advocate lubricating
the propeller with a touch of graphite at the point where it touches the
bushing. Other lubricants may melt the plastic.