Thursday, August 06, 2009

BT-101 rocket ideas

I had these two pieces of BT-101 lying around for a while (hat tip to EMRR) and finally decided to use one.

The cone was an issue for this tube. Standard 4" MPR/HPR cones will fit but seem heavy for this light tubing. I thought about transitioning to a smaller tube since transitions are really easy. I though about this for half a second and then decided to make a cone. You can see how I am doing this in my previous post.

I have no idea what the rocket will look like. I'd like to have some twist so it isn't just another 3/4FNC with a single motor mount. In my often-applied, backasswards method of design, I'll ponder the L/D ratio, the nose cone shape, and various on-line resources to see it might match a 'real-world' rocket or missile.

I've also thought about a design that I came up with shortly after becoming a BAR. This design has a full length motor mount that mates with a plug centered on the nose cone's base. This forms a piston that ejects the cone. No centering rings are used. Instead, the motor tube is centered using 4 strakes at the base. The 'chute resides in between the outer body and the motor tube. Here's the original rocket that used this concept.

I am shocked how often the dimensions of various seemingly random components seem to match up. A thick walled 24mm tube and two thick paint stirrers fit perfectly inside the BT-101. If I go with the design described above, I'll have my strakes with minimal cutting.

This rocket should be fairly light, but I was thinking about a 29mm mount. I'm now feeling a 24mm cluster might be in order.