As a DIY guy, I couldn't resist the challenge of building a model rocket from scratch. The idea of building each piece with my bare hands and mental creativity was too much for me to shy away from. And as a kid, I built several rockets from kits, and enjoyed taking them down to the local park and sending them towards the sky - so I kind of wanted to relive those moments as well.
Turns out, it's easier than I thought to build a model rocket from scratch. And if chances are, it's easier than you're thinking, too. That's mostly because model rocketry is a pretty basic science: Use a straight body tube with a symmetric nose cone, make sure the fins are flat and are perfectly vertical (up and down along the body tube - preferably at or very near the bottom), put together a parachute or bright streamers and throw some flame retardant material between them and the engine and, well, you're ready to go.
Keep in mind that you'll still need to buy some parts at a hobby shop, such as the engine and probably a nose cone and parachute as well. That's not to say that you can't go the extra step and make these yourself, but it will be much harder and time consuming. Personally, I wouldn't recommend building your own model rocket engines because, well, it's very dangerous. If you're confident in what you're doing and have the materials on hand, then I guess you can make that judgement call for yourself. But personally, I like where I live, so I don't want to blow it up in a horrible chemistry accident. Just saying.
What You'll Need To Build A Model Rocket Without A Kit
- A body tube. You can go pure DIY and use a cardboard tube you have laying around the house, such as a paper towel tube or a wrapping paper tube. OR you can buy various sizes of body tube material at most hobby shops.
- A nose cone. If you've got an engineering mind you could, theoretically, design and build your own nose cone. That seems like too much math for me, so I'd just buy one. Besides, you can find them for about a buck.
- A parachute. I've experimented with all sorts of DIY parachutes, and nothing works as well as the ones you'll find at a hobby shop. If you do create one yourself, remember that it needs to be fire retardant, light enough not to make the rocket top heavy, and big enough to work properly.
- Tail fin material. The kits use balsa wood for its light weight, so that's always a good choice. You should be able to find thin sheets of it at most hobby stores. Or you can do what I've done several times and use thick-pressed cardboard from items around the house. Some people have used metals, but personally they seem a bit heavy, and weight is the enemy of maximum altitude.
- Wadding. This will go between the engine and the parachute. When the engine burns all its solid fuel, it will send a big blast up through the rocket and blow off the nose cone, allowing the parachute to come out, open and safely glide the rocket back to the ground. You don't want the hot gasses from that engine "pop" to burn or melt anything.
- Engine. These are available at hobby shops and even department stores. I've heard you can order them online, but I've never tried, because I'm not sure if they'd qualify as a "hazardous material" and require more expensive shipping. You can check for yourself if you'd like.
- Metal Engine Brace. This is a simply piece of metal that holds the engine in place. You can buy them or build one yourself from nearly any metal, a vise and a pair of needle nose pliers.
- Paint. What's the point in building your own model rocket if you're not going to make it look cool? Spray paint is great for base colors, and model paints work well for details. You can even use decals if you like.
Building The Body
What I'd do before even starting is make sure there's an engine that will fit the material I'm going to use. You'd be surprised to learn that there isn't a "standard" size amongst paper towel, toilet paper and wrapping paper rolls. If you're going to use one of these, take it down to the hobby shop and make sure there's an engine that will fit.
Same with the nose cone.
Once you're squared away, simply cut the tube to your desired length. Be sure to leave plenty of space for the engine, the parachute, wadding material and the back of the nose cone.
At the bottom, glue in the engine brace. These are basically long, flat pieces of metal with a small "L" bend at the end. That small bend should bend around the bottom of the engine and keep it from falling out backwards. I'm sure there are specific instructions on size somewhere online, but I personally build mine to allow about 10% to 20% of the engine to sit outside the body tube.
As for the top, you'll need to put together a safety line to keep the nose cone attached to the body once the engine blows the top, otherwise the cone could end up anywhere. You can use stretch rubber band material, twine or even rubber bands themselves. You'll need to glue one end to the inside of the body, but set it back far enough so that it won't interfere with the nose cone itself.
Building The Fins
I'm no engineer, so I'm not going to say that I know what I'm doing here. I'm sure there is an instruction book somewhere that gives some very detailed math equations for the size, shape, weight and general look of tail fins based on the rockets overall size, weight and who knows what else. So, for legal purposes, find that book and disregard what I'm about to tell you.
Still with me? Okay. First off, don't sue me if something goes catastrophically wrong!
What I usually do is get really creative with the fins. That's because it's about the only way to differentiate your handy work from that of a kit. I mean, if you want triangle fins, why not buy a kit and call it good?
I only use three fins, but I'm sure you could go with four or more. Just make sure to use at least three, as any less than that will make the rocket unstable in flight. Oh, and if you want to build a rocket without tail fins, check yourself into an asylum before your hurt yourself or others. It's not a smart move.
I like making pretty abstract fin designs. I sketch them out on paper first.
Then I'll stack all three pieces of fin material together and make sure they can't move independently of one another, put the paper design on top, and carefull saw the shape. I do them all at once so that they are perfect replicas of one another.
Then all you'll need to do is glue them to the body. Elmer's glue works fine, but I've never tried metal fins, so if that's your cup of tea you'll want to ask a pro what kind of epoxy to use. Make sure the fins stay perfectly vertical, and that they don't wobble left or right during the drying process. You should be able to look down the body tube and see the imaginary line where the fins meet right in the direct center of the body.
It gets pretty easy from here.
Attach the nose cone to the rope or rubber band stuff that you glue in to the top earlier.
This model rocket is all yours, from the design to the construction, so why not make it look as awesome as possible? I'm not going to go into the details of painting (quite frankly because I'm a horrible painter myself).
Or, you could always do what I do every once in a while and leave it unfinished. Kind of has a "rat rod" look that way. I would recommend going over it with some clear coat just for protection.
And I should mention that it's okay to paint the rocket with the nose cone in place, especially if you want an even look. But - and this is a BIG BUT - remove it once you're done painting. The last thing you'll want is the nose cone "glued" in place when the paint dries.
So there you have it, a simple guide for building your own model rocket from scratch.