I have not built a two-stage rocket since I was a teenager. I am going to be trying for my NARTREK certifications, and one of the tasks to complete is a multi-stage rocket build and launch. This article will document an Estes Supernova two-stage rocket build.
It is a classic Estes rocket kit. Cardboard body and motor mount tubes; balsa fins; plastic nose cone and parachutes; and rubber shock cord. Let’s get started!
There is a minor error in the instructions for the fin preparation for this rocket. In the Fins Preparation section of the instructions, step number three; it calls for rounding off the leading edges of the fins. The problem is that the booster fins are pointed up in the final model. So for three of the fins, the rounding edge should be the “trailing” edge of the fin.
I sanded the edges of the fins marked by the yellow arrows (see picture). Again, this is not a big deal but I am a little OCD on some of this stuff. You could round off all the edges except the edge that is glued to the body tube and be done with it. A lot of builders do this for every rocket they build.
Motor Mount Construction
There are two motor mounts for this rocket, one for the booster stage and one for the sustainer (main body) stage. The mounts are slightly different for each.
One modification to this kit that I am making is using kevlar for the shock cord and chucking the elastic band. Kevlar is stronger and lighter than rubber. I purchased the cord from Apogee Rockets.
Another change is anchoring the cord on the motor mount and not using the paper connection inside the body tube as the instructions list. This makes the connection stronger and keeps the inside of the body tube clean for a good parachute ejection. Once the glue on the spacers has dried, I cut a notch in the spacer to let the cord pass through it into the body tube. I tied the cord around the motor mount tube with a square knot. The cord and knot were then tacked down with 5-minute epoxy.
Once that dried, I glued the motor mount with the shock cord into the main body tube. The booster motor mount was glued into the booster body tube.
For small rockets, I use the Estes Fin Alignment Jig to line up and attach the fins. It is well worth the price as you can attach all the fins at the same time and the jig holds them in place until the glue is dry.
The fins on the booster tube were attached first. Put a thin film of glue on the root edge of the fin and let it dry for a minute or two. Then put on a thicker bead and attach it the the booster tube. Use the jig to align the fin and clip it to the jig and wait for it to dry.
Once the fins are dry add a fillet to each side of each fin to strengthen the connection to the body tube. The fillet is simply glue placed on the joint and worked into a smooth joint with your finger.
This rocket kit has a clear payload bay. It is large enough to hold my Jolly Logic AltimeterOne altimeter which I purchased from Apogee Rockets. This will allow me to knock out two NARTREK flight requirements; conduct a two-stage rocket launch and carry a payload on a flight. To use the altimeter, I drilled an 1/8 inch hole in the clear plastic payload bay.
The Estes kits are always fine except for one item, the plastic parachute. I replaced the plastic parachute in this kit with a Top Flight Recovery nylon parachute. It is just as light but does not tear as easily. I attached the parachute to the eye bolt on the payload bay. The shock cord runs from the motor mount and is also attached to the payload bay eye bolt.
I washed the plastic nose cone. Plastic parts should be washed with soap and water to remove any material that will stop the paint from adhering. The rocket was primed with white Valspar primer. I painted it silver and black so that the paint scheme will match the included water-slide decals. Once the decals are applied, the entire rocket was sealed with a clear gloss topcoat.
Lessons Learned / Mistakes
- I forgot to seal the fins before I attached them to the body tubes. Balsa wood needs to be sealed to create a nice, aerodynamic surface. I have been building large rockets and sealing the fins after attachment is much easier.
- The body tube grooves should have been filled. I figured they were small enough that the primer would fill them. Wrong.