Saturday, February 13, 2010

Viper IV building part V

Over the last few days, I've actually managed to get the fins on the Viper IV.

Since it's been pretty wet and humid the last few days, I knew that trying to glue each fin on with wood glue would not work, because it would take forever to dry and the bond wouldn't be that great. Instead, I spread superglue along the joint between the fins and motor tubes, forming an instant bond that holds the fin in place. Then, I used wood glue to make a fillet. They're still finishing drying and will require a second coat, but once finished all four fins will be strongly attached to the motor tubes with smooth joints.

The way that the Viper IV is built is somewhat unusual. For most mid-power rockets, one glues the motor mount inside, then attaches the fins either directly to the body tube, or through it. Every major component is glued to the body tube, which is the foundation of the rocket. With the Viper IV, the foundation is the quad motor mount. It takes a lot of work to glue the motor tubes together, add positive retention, fit the motor mount into the coupler, and glue on the fins. Only at the end is the whole subassembly added to the body tube, and the only other things glued to the body tube are the shock cord and launch lug.

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