Introduction: Awesome Model Rocket Scratch Built From Readily-Available Materials
Believe it or not, You can build an awesome, two-stage, model rocket just from parts you can find in your average home and some materials available online and at a regular hardware store. Why buy an model rocket kit when you can experience the thrill of designing a rocket the way you want to and then actually being able to build it? All it takes is doing some research, gathering some materials, and spending some hours using your hands.
Step 1: Planning and Designing Your Model Rocket
Before you start planning you rocket, you must obviously have an idea of what you are going to make it out of and what it is going to look like. Before creating any attempts at model rocketry, I highly recommend reading G. Harry Stine's Handbook of Model Rocketry. It will enlighten you in many of the variables surrounding the flight of a model rocket as well as safety criteria and building strategy. This is the book that got me into building model rockets after picking it up out of pure interest at my local library. Again, I highly recommend giving this book a good read, as it is a nice thick piece of writing containing all the details surrounding model rocketry that I cannot pack into this Instructable. Anyway, a good material for building your model rocket out of is cardboard. It has a good structural integrity for its lightness and availability. I knew that I had empty Christmas present wrapping rolls (all that was left was the cardboard cylinder that the wrapping was coiled around. I took measurements of the cardboard tube and then created a model of the cylinder on Google's SketchUp 8. I decided that I wanted my rocket to be multi-stage, meaning that it would have more than one set of motors. I decided that the long cylinder from the Christmas wrapping would be the core of my rocket, which meant that it would be the part of the rocket that would be carrying the payload. I then realized that I wanted some boosters for the first stage (the first set of motors to fire) so I found some small cardboard cylinders from empty toilet paper rolls in the recycling bin. Thus, I figured out what I was going to make my rocket out of and how it was going to look like.
Step 2: The Nose Cone
To begin building my rocket I first began by creating the nose cone. I found some cone-shaped paper cups I used for picnics and smothered it in regular Elmer's white glue to make it more rigid. Although it is paper, the cup will not get crushed due to air resistance because it is shaped like cone. You can very well make a paper cone yourself by rolling up some copy paper. I do not recommend using construction paper because it will get wet and soft when you apply the white glue. Once you have done that, place the cone on top of rocket. Cone will most likely be to big in diameter and your rocket might look like it has a dunce hat on top of it. If this is true, as it was for me, just feel where the cone contacts the edge of top of the rocket. Trace that spot with a pencil and then take of the cone, fold it in half, and cut off the excess. I recommend folding it in half so that at least both halves will be pretty consistent with each other. Once that is done, put the cone back on, making sure that is fits perfectly and there is no overlap, and then smother the joint in more white glue. Let it dry and you will have a pretty good nose cone.
Once you have put on the nose cone, you must cut the rocket to separate the nose cone from it. I recommend cutting 1-2 inches down from the actual cone a.) so you'll have more space for a hefty payload and b.) so it looks more like a real capsule carrying astronauts or the like. The reason I said that you need a hefty payload is because if you read that book i mentioned previously, the rocket's first test before actual launch is if it is balanced. Of course, you test if it is balanced after it is complete, but you have got to insure that the nose cone is very heavy so when you tie a string at the middle of the rocket and swing it around in a circle, the rocket is mostly horizontal and the engines at the bottom are not making the tip go up (which is called yawing). That can be catastrophic in flight.
Anyway, as I was saying, cut the rocket 1-2 inches down from the actual cone. I don't recommend a scroll saw or band saw because they are so powerful they might rip up the whole operation. Just use a regular, thin-bladed hand saw and cut very gently, preferably in as straight a line as possible.
Once you have cut off the nose cone, you might want to start securing the payload. You want to find the balance between too heavy and too light. If the payload is too heavy, the rocket won't go far. If the payload is too light, the rocket will yaw. If you are making a rocket like mine, I suggest creating a heavy weight astronaut. The way to do this is to find a bouncy ball about the size of a strawberry. The dense rubber used to make it bounce will be quite heavy, so you've already got some weight for the rocket to carry. All you need to do to make it astronaut is to create a body out of thick steel wire so it will kind of look like a bobble head stickman and then wrap the arms and legs in electrical tape to beef them up. A paint job will bring it to life.
To secure the astronaut to the nose cone I devised a pretty cool locking device. I cut out a piece of cardboard to the circumference of the nose cone and at its middle glued on another vertical slab of cardboard with gorilla glue. I drilled a hole through the vertical slab and then right through the nose cone. I then cut a piece of thin dowel a little longer than the diameter of the nose cone. The way this works is that you sit the astronaut down on the little circular piece of cardboard so that the vertical piece of cardboard was between his legs. Then pushed him into the nose cone and stuck the dowel through one hole in the nose cone, through the hole in the vertical piece of cardboard, and out the other hole in the nose cone. The inspiration for this came from when I sat down in a roller coaster and the safety bar was lowered.
Now that you have your capsule fitted with an airhead-astronaut, you need to secure the capsule to the rest of your rocket. What I did was I cut off the end of a cardboard tube from a toilet paper roll and then glued that ring of cardboard to the inside of the end of the core so that the capsule would fit tightly on top of it. If the ring of cardboard isn't thick enough to insure tightness, you can add masking tap to it to make it thicker. But don't make it too tight!
The reason that all model rockets need a capsule that is separate from the rest of the rocket is that the way core engines (which will be touched upon in a later step) is that they burn and when they stop burning they create a little explosion. The pressure from this explosion pops off the nose cone and lets out the parachute, which allows the rocket to descend safely back to Earth. But the parachute must be secured to the rocket, and the traditional way to do this is to tie an elastic band between the capsule and the rocket so you don't lose the capsule and tie the parachute to that elastic band. The way to do this is to anchor the band to the core by making a hole in a small piece of cardboard and the pulling the band through the hole. Tie a stopper knot at the end of the band and then smother the side of cardboard that has the stopper knot pulling against it with gorilla glue. Then press the stopper knot side against the inside of the core and let it dry. Then you will have a secure anchor. To secure the elastic band to the capsule all you need to do is drill a small hole in the bottom of the circular piece of cardboard upon which the astronaut is sitting on and then pull through the band and tie a stopper knot. Attach the parachute, which you can buy online, at a hobby store, or cut out of polyethylene, buy tying a loop in its strings and threading the elastic band through that loop before you make the stopper knot in the capsule floor. Thus, your nose cone is complete.
Step 3: The Boosters
When you are making the boosters, you are essentially just putting a paper cone on top of the cardboard tubes from the toilet paper rolls exactly the way you put the nose cone on top of the core. Then all you need to do is secure the boosters to the first stage core by first applying gorilla glue on both sides and then sticking on the boosters. Clamp the boosters to the core gently using rubber bands and let the glue dry. If you are wondering why I glued the boosters to the first stage core instead of attaching them in a way where they can fall off after they finish burning, I'll tell you that when you put boosters on the first stage of a model rocket, you are doing it just to add engines and essentially thrust and height. It is only with real rockets that the boosters must fall off because they have a different burn time than the core.
Step 4: The Inter-stage Divide
If you are making a stage rocket, you must cut the rocket to divide the first stage (the first set of engines to fire) and the second stage (the second set of engines of fire). To do this, I recommend cutting the core as far down as possible but not to far down as to not interfere with the second stage engines (see steps 6 and 7). Again, use a thin bladed saw to make the cut. As with the nose cone, insert a cardboard ring cut from a a toilet paper roll tube, but I recommend using a longer ring (cutting the cardboard tube at its middle). As you can see, on my model rocket, the inter stage divide ring was not tight enough, so I put on a little duct tape to add thickness. Although the ring is thicker, the divide is still loose, looser than the nose cone at least. It must be because there should be no delay when the second stage fires or it will set the first stage on fire. On smaller multistage rockets people don't even put the cardboard ring on the inside. Some just wrap some scotch tape around the outside of the divide. Be careful to note that you want to have the first stage core engine as high up in the rocket (before the divide) as possible and the second stage and low in the core on the other side of the divide as possible. The reason for this is that if you buy model rocket engines that are production made by a well-known and reputable manufacturer (which I highly recommend; building your own engines is very dangerous) then the booster engine that you will put in the first stage core will make a little explosion when it is done burning which must funnel up the core to light the second stage. The farther apart you space the first and second stages will decrease the chances of the second stage's lighting.
Step 5: Fireproofing
Due to the fact that the booster engine in the first stage core must create an explosion that funnels up the core to light the second stage, there must be some fireproofing done to the inside of the core. After all, you're going to want to launch your rocket more than once, right? I recommend gluing some aluminum foil to the inside of the core between the first and second stage engines just to be safe.
Also, I mentioned that the second stage engine in the core also creates a little explosion after it is done burning to make the capsule pop off and the parachute deploy. In the picture below, you can some yellow stuff near the second stage core engine. That is recovery wadding, which is pretty much fireproof paper. The picture was taken after a launch and I had removed most of the charred wadding, but you would obviously have about five to ten pieces of it in their, depending on the size of your engine. The paper will absorb the fire and just let the force through, so don't worry about putting too much in. TTh
Step 6: The Vertical Stabilizers
The vertical stabilizers are necessary to insure that your rocket flies straight. They must be, in scale terms, bigger on model rockets than on real ones because model rockets do not go into space and are more affected by the air because they are substantially smaller. You can have fun with the shape of your vertical stabilizers, but vertical stabilizers that are parallel to each other must be the same shape and size, and they must be perfectly aligned. I recommend drawing a circle the circumference of your rocket's core on a piece of paper and the using a protractor so you can draw lines where you need to put vertical stabilizers at the correct angles (ex: if you want three stabilizers, draw a line ever 120 degrees). To make a vertical stabilizer, first draw out the shape on a piece of basswood or balsa that is about 1/8 and 1/16 inches and cut it out using a carving knife or X-acto knife. Attach the vertical stabilizer to the rocket with some gorilla glue and duct tape it to clamp. I left the duct tape on my rocket and just covered it up with tape because I didn't want to destroy the bond by ripping it off.
Step 7: The Core Engines
For the first core's first stage I used Estes's B6-0 booster engine and then for the second stage I used Estes's B6-4 engine. Because the engines are quite small and do not fit tightly into the rocket by themselves, I created a technique where I can center an engine inside a booster or core and be able to switch it out easily. Basically, I slide on two cardboard rings onto the booster. These rings are the diameter of the of the core and/or booster. I found that I had two different types of cardboard tubes from toilet paper rolls: one was thicker, the other was thinner. The thinner could fit inside the core and the thicker tube, so then I shaved a little more cardboard off the rings on the booster engine and slid it, completely centered, into the thin tube. I then capped tube with more cardboard and then put another cap on the the bottom with a small hole in it so there would be a hole for the exhaust to come out the engine. I then simple slid the tube into the core and it fit. For more on this technique, see the next step.
Step 8: The Booster Engines
I used the same technique for the boosters as I did for the core engines. For the boosters I used the Estes B6-0
Step 9: Decoration
To decorate my rocket I used pink spray paint and simply applied three thin coats. I created decals by going onto Microsoft word and posting images and text in text boxes that were the same color as the rocket. I then printed the decals out and glued them. Note that the image with the red decals was for mt launch pad, which I painted red. I do not recommend applying lacquer or a spray-on enamel because it will probably way down the rocket, but I have never
Step 10: The Launch Pad
The easiest way to build a launch pad is to just get a piece of 2 inch by 4 inch pine and cut two-24 inch pieces off of it. Then put one piece of 2x4 against the other at its middle so it looks like a capital T. Secure the bond with two screws through the middle of the top part of the T and into the other piece of wood. Then drill a 3/4 inch hole in the bottom of each tip of the T and stick into each hole a 3 inch long piece of 3/4 inch dowel. Then drill a 1/4 inch hole in the top of one of the pieces of 2x4 near the joint. Stick in a 3 to 4 foot long piece of 1/4 inch metal dowel into the hole. Then bend a piece of 12 inch by 12 inch piece of sheet metal into a kind of capital W and secure it to the T with a couple of nails.
The piece of sheet metal will act as an exhaust deflector at launch time. The metal dowel, meanwhile, will set the rocket on its course. The way it works is you must have at least two guides in your rocket. The guides are basically rings that you can shape out of steel wire and stick into your rocket. Secure them with globs of gorilla glue. Make sure that the rings are aligned with each other and will not interfere with vertical stabilizers. When launching, slide the dowel through the guides and set the rocket on top of the crest of the exhaust deflector.
Step 11: Ignition
Rocket engines come with instructions and spark plugs and all that good stuff, so I'm not going to go into much detail on that. You can. procure a launcher for a multistage rocket online and at a hobby store from a reputable and well-known manufacturer. I recommend doing this over what I did.
What I did was I had a launcher from a single-stage rocket kit that was meant for starting only one engine at time. But I because I needed to start three engines at the same time, I decided to divide up its power. Since the launcher is really just a battery pack with a switch and wires tipped with alligator clips that clip onto the starter plugs, I cut six pieces of insulated copper wire and soldered alligator clips on the ends of all of them. Then I took three and soldered them together and then soldered the other three together. All I had to do was clip those two bunches to the launcher's alligator clips and then I could start three engines at the same time. It worked, just not well. Because the launcher was designed for starting only one engine, it kind of killed the battery starting three. On launch day it took a couple of tries to start the rocket.
Step 12: Launch
At launch, make sure you are in an open field with favorable conditions. I recommend having a fire extinguisher on hand, just in case. Take all safety precautions seriously and don't forget to have fun!