Last Saturday, my 8 year old son participated in his first Space Derby with his Cub Scout pack. A lot of boys, parents, siblings, and Cub Scout leaders showed up for the event. What is a space derby? Well it is probably a little different than what you imagined.
Each Cub Scout gets a Space Derby kit through their Cub Scout pack. The kit consists of balsa wood that each participant will use to form the body of a rocket. There is also plastic material in the kit that can be cut to fashion fins for the rocket. Here is where it starts to sound a little strange. There is also a propeller in the kit. A propeller?!! I thought this was a rocket? Well, it is supposed to look like a rocket, but the propeller actually propels the rocket. The Cub Scouts race their rockets four at a time. The rockets hang horizontally from a fishing line and the propellers are powered by a rubber band that comes with the kit.
The rockets are judged in three categories; speed, beauty, and originality. It quickly becomes apparent that the primary thing that makes a rocket fast is its’ weight. Since all the rockets are powered the same and wound equally, the lighter your rocket, the faster it will go. However, if you make your rocket light, you risk structural failure when the rubber bands are wound. So there is a balancing act to having a light, but strong rocket in order to have a fast one.
My son and I decided to go for the beauty category since this was his first space derby. We wanted to get an idea how the other rockets would perform in terms of speed this time out. We followed the directions in the kit and started by gluing the two balsa wood halves together. Later we used very course sandpaper to begin making the shape of our rocket. I later found out from some of the other parents that a potato peeler works wonders for shaving wood from the body to get the rough form of the rocket. Not having this information to begin with, we used sandpaper. Once we got the basic shape we wanted, we used finer sandpaper. We switched to 400 grit sandpaper, then finally 800.
Next we sprayed the rocket with primer. Once the primer dried thoroughly, we sanded it with the 800 sandpaper. We then added another layer of primer and sanded it again. We continued this process until the rocket body was smooth enough to satisfy us. I have a friend who said I should have used sanding primer. He says it would have filled in the cracks in the balsa wood with only one or two coats. I’ll have to take his word for it. I used regular spray paint primer…the cheap stuff.
Once we were finished priming and sanding, we sprayed a coat of candy apple red on the body. When spray painting, there are a few tips that will make a huge difference in how your finished model will look. Spray paint in a well ventilated area only. It is important that you hold the spray can the correct distance from your model…about 6 inches is usually recommended. If you get it too close your paint job will have runs in it; too far away and your paint job will have an orange peel effect (it will look rough and dull). Keep the can moving while spraying… again, too much time spent in one spot will result in runs and a not-so-great paint job.
When spray painting your rocket, you can fashion a fuselage holder from a clothes hanger. This prevents you from getting spray paint all over your hands and from getting finger prints on your fresh paint job. Be sure to have a secure spot where you can place the end of your hanger, keeping your fresh paint from touching anything until it dries. Allow plenty of time for your paint to dry (30 minutes) before adding a second coat or (2 – 4 hours) before touching the rocket body, depending on humidity.
Once the first coat was dry, we added a second coat of candy apple red. We painted the fins and the propeller chrome after priming them. Since we didn’t have any decals handy, I used silver and black sharpies to draw lightning bolts on mailing labels. I then cut the lightning bolts out and stuck them on the rocket body. My wife used a fine tip black sharpie to add Capt. Justin Rodgers to one of the rockets’ tail fins.
Justin’s rocket won first place in the beauty category. He did OK in terms of speed, but we will definitely make a lighter rocket for next year. I hope you found some useful tips in this article for building your own winning space derby rocket.