Indoor
(Alka-Fuji)
Rocketry!

Objective

This activity is a lot of fun, and a wonderful recruiting tool.  The cadets get to take home something neat to show their friends, and the cost is only a few pennies per cadet.  (Consider doing this at a recruiting booth, too.)  The objective is to build and launch a simple rocket powered by a combination of liquid and solid fuel (just like the space shuttle!)

Time Requirement

About half an hour to an hour, depending on the size of the group.

Materials

Each cadet will need:

• One sheet of 8 1/2 x 11 paper (colored paper is good)
• One Fuji 35mm film can
• One half of an Alka-seltzer tablet

Common supplies for the group to share:

• A small amount of water
• Scotch Tape (the "magic" kind is more water resistant!)
• Scissors
• A circular object to trace (like a roll of masking tape)
• A pencil for tracing the round shape
• A towel to be used as a launch pad (indoors)

Background

The basic principle of rocketry is Newton's Third Law: For every action there is an equal an opposite reaction.  Big rockets use chemicals to produce a stream of gas out the tail end of the rocket to propel the rocket upwards.  Sometimes the fuel is liquid, sometimes the fuel is solid.  But, in all cases, a gas is ejected from the tail of the rocket.

In our rockets, we will produce a very safe gas - carbon dioxide.  Our fuels will be water and Alka-Seltzer.  There will be no flames, and no toxic chemicals.  If the cadets decide to drink the rocket fuel, they might even soothe an upset stomach!

Procedure

This may look complicated, but once you have done it once it's really obvious and simple.  Trust me, it's worth the time to learn to do this - see the discussion below.

1	Start with a single sheet of letter size (8.5 x 11) paper for each participant.  (An assortment of brightly colored sheets distributed among the class makes the rockets look more interesting, and the kids get to choose their favorite color.) Fold the paper not quite evenly in half the long way.  There should be about an inch between the two edges.
2	Unfold the paper, and cut along the fold.  This leaves one sheet slightly larger than the other one.
3	Draw a circle at one end of the smaller sheet.  (A large cup, or the inside diameter of a roll of masking tape works perfectly.  You want it to be just a little smaller than the width of the smaller sheet.  Cut out the circle, and square off the end of the remaining paper.   Discard the "ring" illustrated in red to the right.
4	Now fold the smaller rectangle in half the wide way, so that it looks more or less square.
5	Unfold the rectangle, and cut along the fold, leaving two squares...
6	Now, line up the two small squares, and fold them in half to make a mini "book" out of the two sheets.   Keep the fold of the book to the right, and the open edges to the left.
7	Cut up along the fold.   When you get about halfway up, take a shortcut to the top, opposite corner.   (See diagram at right.)  Discard the red shape.  (You might want to show younger kids that if you unfold the scrap, it looks sort of like a rocket.  They like that.)
8	You now have six pieces of paper in various shapes.
9	Take the circle, and cut out a slice.  I like to say "have a piece of pie that is so big that Mom would be really mad and call you a pig if you did it to a real pie.  (They like that, too.)   You are left with a Pac Man (which only us old geezers know about.)
10	Your six pieces should look something like this...
11	Now, for fun, have them trade with others to get a variety of colors if they like.  Multi-colored rockets look better than solid ones.  And they'll make these diagrams a little easier to follow...
12	Time for the film can, which will serve as the combustion chamber.  A Fuji can is clear, and looks like the one illustrated to the right.  These work really well.  Flat-lidded black and gray Kodak cans work too, but sometimes they just dribble instead of popping really good... The lid of the film can will serve as the launch pad...  You can remove it for now.
13	Take the film can, and wrap the paper in a tube about halfway up the can.  Make sure the open end of the can sticks out the bottom of the rocket!  Now, take a large piece of tape, and go all the way around the tube, taping the paper to the film can in the process.  Have the film can stick out about an inch from the end of the tube, and make sure it's taped down really well.  (It's gonna get slippery!)  Take two small pieces of tape and tack down the seam, too.
14	Have the kids tape down all four fins on the long edge to the desktop.  Have them have four pieces of tape standing by in reserve...
15	Line up a fin with the end of the body tube paper, going right down the middle of the tube.  Press down the tape to stick it down.  Then, flip it over, and fold it back.  Place the extra piece of tape on the other side of the fin.  If you do it right, the fin will spring back and stick straight out from the body tube!
16	You now have a fin with a piece of tape on each side, as shown at right.  It works best to then have them do the second fin directly opposite from the first one...  Once they have the two opposite fins locked down, add the two other fins exactly halfway between the first two, and opposite from each other.
17	Your fins will now look as at right.  Notice the large amount of the film can sticking out the bottom of the rocket, and the ring of tape going all the way around taping the paper to the film can...
18	Now line up the two straight edges on Pac Man and make the two edges touch.  You now have a cone, but it will be too big.  So overlap the two edges  somewhat until the ring at the at the bottom of the cone is about the same size as the diameter of the film can and rocket body tube...   Secure the seam in the cone with a single piece of tape.  Then, add "ears" to the side of the Samurai helmet, and place it on the top of the rocket and secure it.
19	To launch your rocket, do the following: Insert a small amount of water (like a tablespoon, or 1/2 an inch in the bottom of the film can - a small amount works best!) When you say "GO!" have the cadet drop in half an Alka-Seltzer tablet that was previously issued to them. Have them snap the lid (the launch pad) onto the film can.  MAKE SURE IT GOES "CLICK!"
20	Then it gets exciting... Have them set the rocket on the ground and step back. When sufficient pressure has built up, the rocket will launch!
Note	I like to go in groups of about five at first.  Hand out all the tablets, then pour  the water into each rocket.   Say "Go!" hand have the group of five drop in the tablets and snap on the lids.  Some go quickly, and some go slow (the longer the delay, usually the more powerful the thrust!)  After everybody has gone once, end with a final salvo of ALL of 'em.  Great photo op...  I have done about forty at a time to much amusement of the participants! Another hint - once the rocket is built, have them test-snap the film can lids in place.  Have them practice until they are good at it, and can make it click every time without crushing the paper rocket.  (It's always harder once the rocket is slippery, and there is the "bomb ticking" nervousness kicking in...)

 

Discussion

A good expansion of this activity is to have the cadets suggest design modifications.  One group punched a hole in the body tube to allow the film can to be pinched close.  Another group taped the Alka-Seltzer to the lid of the film can, keeping the tablet dry until the film can was inverted.  You can also experiment with varying the amount of water, the size of the tablet, the number of fins, the length of the body tube, etc.

Alka-Seltzer (or a generic equivalent) can be purchased in bulk cheaply.  And the Fuji 35mm film cans are FREE.  Really.   I lived in a very small town, and I went to about half a dozen photo labs.  I asked to go through their empty film can bins and sort out the clear Fuji containers, and they all said "help yourself!"  Some said "Here, take them all.   Sort them out at home."  And that works, too.

The Fuji film cans seem to seal the best, although the black and gray Kodak cans can work in a pinch.  If you want to know what a Fuji film can looks like, ask your photo development shop - they should know which are which if they have been doing this for a while.

One other hint - make an Alka-Fuji rocket for the film shop, and demonstrate for them how it works.  They LOVE 'em.  You might even get them to leave it on display, along side a few recruiting brochures...

I had great success making Alka-Fuji rockets at a recruiting booth.  Kids were walking around carrying brightly colored rockets, and telling passers by "Hey, they're giving away free rockets over there!"   That got the kids to come and talk to us in droves.  Our cadets supervised the construction and launching, leaving the seniors time to talk to the parents.  The parents saw their kids getting excited and having fun, and saw very sharp and polite cadets leading the way.  The seniors explained that this was just a small part of the CAP cadet program - leadership and aerospace - but that there was also physical training and moral leadership and a lot more.  It works really, really well.  As a final kicker, have some larger rockets around, like the Estes type.  The visitors in the recruiting booth will ask "Can I make one of those???"  A reply of, "Sure, our cadets make and launch rockets like that all the time.  But you'll have to join up..." slams the deal home.

 

Safety Concerns

This is very safe and non-toxic.  When doing this activity indoors, be careful about slippery floors.  And, have the cadets stand back and not try to get a "top view" once the rockets are primed to go - during on event we had a rocket pop off into a face that was in the wrong place at the wrong time.  (No permanent damage - more embarrassment than anything else!)

Adapted from: Aerospace 2000, Volume 1
Published by the Aerospace Education Training Directorate
National Headquarters, Civil Air Patrol.