Friday, May 29, 2009
D-Fusion Bomb - named, and built
I finally got around to building a rocket form the D-Fusion Denny's drinking cup. The background can be found by following the tag at the bottom of this post.
I had previously ground the threads off the lid (aka the nose cone). This left a short shoulder so I was happy when I found 54mm tubing fit snugly in the lid's inside shoulder. This provided more support and an inside body. An inside tube will keep the ejection gassed from crudding up the clear outer body and will help with 'chute deployment.
It has a 24mm motor mount held in place with an upper centering ring and the bored-out base of the plastic cup.
The nose weight and 'chute attachment point are embedded in tip of the lid. A 1/4" lug (will want to fly from an HPR pad!) is CAed to the body. The launch rod also slides through a hole drilled in one fin.
Specs: 6 oz less chute; static margin of 0.56 with a D12; 300 ft altitude with that D12; need a -3 delay!!!
I may try to add some positive retention so I can use a 24mm reload since I don't have a D12-3 or an E15-4 in stock. I hope adding a 'phantom cone' to account for base drag was the right thing to do. The only way to tell is to push the button :)