Conehead

Conehead
Cone stabilized rocket

After reading Tim Van Milligan's book about model rocketry, I was inspired to build some sort of cone stabilized rocket. I'm not sure exactly how I came up with doing it in two sections, but it turned out to be a really fun flier. It seems to be extraordinarily stable. It has flown in all sorts of wind conditions and yet it always stays pointed up.

It flies great on C5-3's and C6-3's. It is so draggy, it never gets going too fast. And you get a great view of the motor's exhaust all the way up. It should also fly great on D10's .

Building the Conehead

Construction began with the upper section. It uses a plastic nosecone and a BT-20 tube. The bottom ring was made of 1/16" plywood and drilled to reduce weight. The struts were added to reinforce the shroud, which can be seen in the background.

The shroud was drawn in AutoCad, but can easily be done by hand with a ruler, protractor and compass. Poster board was the material.

The nosecone was filled with clay and sealed before being attached to the tube.

I just swagged the lower section. There were two concerns. One was getting the motor far enough forward in the rocket to keep the center of gravity ahead of the center of pressure, so the motor extends halfway out of the lower section. The other concern was setting the forward diameter of this section so that it was just narrow enough to slip inside the aft end of the forward section.

The main materials are 1/16" balsa and poster board. The forward ring is foam board with a piece of poster board in the center. The poster board was perforated with a hole punch. There were three reasons for these holes: The launch rod slides through one of them. Weight is reduced albeit slightly. And some air can flow through it during descent to help keep it stable on the way down. (At least that's my theory :)

The motor is friction fit into the lower motor tube. At ejection, the lower section separates and drops gently to earth and lands on the motor which acts as a shock absorber and slides aft when it hits.

A streamer is attached to the aft end of the upper section. It is rolled up and placed between the sections during flight prep.

In this picture, the upper section has been assembled. The motor is sticking out from its fully inserted position. It sticks in halfway with the lower half fitting in the lower section. At ejection, the motor returns with the lower section.

Conehead in Action With its slow liftoffs, the Conehead makes for great launch pics.

Photo courtesy of Tim Sapp

Here's daughter Haley and wife Paige with me in 2006. The liftoff shot below left was taken right after this picture.

Alternative uses for the Conehead

It makes a great hat

8-15-2010