The Rocket Formerly Known as Black
Step Two
Nose Cone Fabrication
I enlisted the help of a couple of friends to make the nose cone components, since they had both the tools and expertise to do the job properly. Brett McFarland helped turn the aft part of the nose cone out of poplar. I have Tom McGann to thank for producing the front part of the nose cone (the 'stinger') out of steel.
Making the stinger out of steel accomplishes two things: One, it moves the weight as far forward as possible, reducing the amount of added weight necessary to balance the rocket, and; Two, it obviously makes the stinger more rugged.
We attached a 3/8 inch Lucite plate at the base of the wood section to make the sharp corners of the nose base less susceptible to chipping. We attached the plate to the wood block during turning and shaped the entire aft section at once.
So after spending days bent over a wood lathe and spitting out poplar chips, then finally getting the perfect profile, what comes next? Naturally, you want to start drilling holes in it.
The launch lug runs alongside the four-inch center tube, so a hole needs to be drilled through the exaggerated shoulder of the nose cone. I made a wood fixture to clamp the nose assembly to the platform of my drill press. It is shown here, along with the 5/8 inch Forstner bit used to bore out the lug hole. Aligning the bit to the hole location was meticulous and nervewracking.
Running through the center of the aft section is 1/2-inch hollow aluminum shaft The 3/8-inch threaded rod that connects the stinger to the aft eye bolt and holds the assembly together runs through the tubing.
The advantage will be that the pressure of the tightened assembly will be born by the aluminum shaft and not the wood (which is pretty thin at the front) and will withstand impacts better. The center hole was bored out after the turning was complete.
AFT VIEW shows the hollow for balancing weight. The Masonite ring forms the top of the fuselage, attaching to the center tube.
A view of the Lucite aft cone plate against the Masonite forward fuselage ring. This will make a smooth transition!
The shoulder is 3.9-inches wide and 4.0-inches long. It is bored out 2.5-inches so the balancing weight can be moved forward in the nose assembly.
The steel stinger is estimated to weigh about 2 lbs. The wood portion is estimated to weigh about a 1.5 lbs, and the threaded rod and eye bolt should weigh another 0.5 lbs, bringing the total to about 4 lbs before any additional balancing weight is added. The total weight of the nose of the Napkin Rocket was 5.5 lbs, but this rocket should require less -- most of the weight, including the motor, will be further forward here.
A close-up of the 'stinger'. It's so pretty, I almost hate to paint it! This is just over 4 inches long.
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The full nose cone assembly. Over 10 inches long tip to shoulder, 14 inches long total.
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TRFKAB Index
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