Build It - 2

This is a series of posts where we’re building a basic model rocket online. Each post shows part of the process step by step, including pictures and passing along tips and tricks I’ve learned along the way. To learn more about what model rocketry is about, see this Q&A.

The main part of the post is in the extended entry so you don’t have to deal with it if you don’t want to, but I hope you follow along because when we get done you’ll have built and flown your first model rocket. Questions asked from before are answered too.

If you have questions, please leave them in the comments or email me.

The instructions for most model rocket kits are wonderful. Estes has been doing this for years, and their experience shows. Let me stress one point right up front: always, Always, ALWAYS follow their suggestions for glues to use. You can sometimes use an alternate (I have almost 20 different kinds of adhesives for various situations), but their recommended glue will give you the strongest bond.

Looking at the parts

Almost everything that needs assembly tells you to lay out the parts and make sure you have everything, and also to read through the directions first to understand things. This is a simple kit, so do it if you’d like, but it won’t be a problem if you don’t. For more complicated kits, I do recommend doing it.

Lets look at the various parts, most of which are obvious. The biggest tube with the slots cut in one end is the body tube. In a simple rocket like this, it’s main purpose is to hold all of the important bits in their correct places. The nose cone is straightforward, as are the fins. The parachute is the plastic sheet with the strings attached. So much for the obvious bits.

The tiniest tube (it looks like a drinking straw) is the launch lug and it’s used to steady the rocket on the launch rod. The length of elastic is the shock cord, remember I recommended replacing it with a longer piece bought at the store. The two cardboard disks, the medium sized tube and black ring will be put together with that little metal strip and become the motor mount.

Pre-assembly

Using your x-acto knife, carefully cut the fins out of the balsa sheet. They’re die cut, and held in by just a few short bits of wood. If you want to, you can gently sand the fins (with the grain) with the fine sandpaper before freeing them. Make the same kinds of cuts to remove the smaller middle circles from the cardboard disks. Finally, you may need to open the inside of the squared-off loop at the bottom of the nose cone (see the picture). Do all of these carefully, and watch for the sharp knife.

Make sure the fins fit the slots in the body tube. Sand them lightly if needed to ensure a smooth fit.

The following steps are completely optional.

Using the sandpaper, sand the seam on the plastic nose cone until it disappears. This isn’t a quick process, but it does make for a much nicer looking end result.

Lightly sand the entire body tube until you’ve scuffed the shine off. Don’t sand too much, the purpose here is to remove the glassine layer, which will make for a stronger bond between the glue and the paper tube underneath.

Take some of the Fill’n’Finish and thin it with water until it’s about the consistency of pancake batter. Slather it on the body tube (I use my finger) and work it into the spiral groove. You won’t need much, and most of what you use will be sanded away. Let it dry – it’s fairly quick – and then lightly sand. The Fill’n’Finish sands easily, and when you get done there should be no spiral groove left. Repeat if you need to.

Use the same thinned Fill’n’Finish to fill the grain of the balsa fins. Keep the coats very very light, and sand between coats when dry. When you do the fins, do both sides at once, because the balsa will warp slightly and this will help even it out. The warp will straighten out when both sides are dry.

The reason for all this filling and sanding is because the smoother the surface, the less drag which makes for a higher flying rocket. I don’t do it for every rocket, but I do take the time for most of them. The paint job looks much nicer on the smooth finished surface too.

Questions Answered

What is a ‘fishing swivel’? Also known as snap swivels, they’re used to prevent the fishing line from twisting. They have a small loop on one end and a large loop on the other end that opens like an old fashioned safety pin. Here’s a (crappy) picture of a few, and like I said, you’ll only need one, and it’s optional. Also in the picture you can see the package of sewing elastic, the glue and Fill’n’Finish, and an x-acto knife.

Next time, we’ll build the motor mount and attach the fins.

Posted by Ted at December 1, 2003 05:18 AM | TrackBack