Tuesday, October 13, 2015

The Copperhead Rocket - Built from Scratch

This post is about a current project I'm working on. Pictures of current projects will mostly appear on The Rocket N00b Facebook page, so I can focus the blog more on informative stuff for beginning rocketeers. But I think this post has some information for rocket n00bs, so here it is. Check out the Facebook page for more rocket pictures, blog updates, and links to cool stuff.

A few months back, I designed and created a little model rocket as a thank-you for a donor to a fundraiser I was doing for the Bloomington Playwrights Project. It's called The Copperhead.

Once I'd built the rocket, I really loved it, but never got to see it fly. I decided to build one for myself. Last night, while working on about seven other rockets, I just started working on it.

The rocket has forward-swept fins and a small payload section. Look closely at the payload section - the fat upper part of the rocket. There are four tiny holes drilled into the side. That will allow me to use a barometric altimeter in the rocket, so that I can track how high it goes.

While the rocket looks really cool, it's always surprising to see how they come together. The parts alone don't look like much.

A few standard-sized tubes, a sheet of basswood, and a nose cone purchased online look kind of humble when you first begin building a rocket. The parts can come together quickly, though, and before you know it, you have a pretty great-looking rocket.

Much as I like the standard Copperhead, it suddenly hit me how easy it would be to put a booster stage on it, transforming it into a two-stage rocket. Here's what the design file looks like:

The first motor launches the rocket into the air. When the propellant is burned up, it ignites the motor inside the upper stage, and the booster is jettisoned and tumbles back to Earth.

Adding a stage to a rocket can boost its altitude - and its velocity - dramatically. Instead of launching the main part of the rocket - called the sustainer when it's part of a multistage rocket - from the ground, you're basically launching it from high in the air, already moving upwards. The results can be spectacular. Adding a booster to my Copperhead rocket will take its peak altitude of 740 feet up to over 1300 feet - nearly double!

If you understand the basics of rocket stability and model rocket staging, you could probably build a booster for just about any model rocket, adding altitude and speed. Imagine making that fat, heavy Big Bertha into a high-flyer! But beware, this increases the likelihood of losing the rocket! When launching a multistage rocket, you need a larger field, and may need to put less powerful motors in it.

But building a booster requires only a few extra parts, some knowledge of the staging process, and a little modification and care in building the rocket. I'll cover staging here more extensively in the future.

Here are all the parts I'll need to build this rocket with a booster stage, minus a shock cord and parachute:

The brown tube in the right is a tube coupler. I'll only need a 1-inch length of it.
The motor mounts are already installed in the main body tube and the booster body tube.
 Still looks like a pretty humble pile of parts, doesn't it?

That's one of the many cool things about rocketry. You start with some simple paper and plastic bits, and end up with an astonishing flying machine.

I like the forward-swept fins on this rocket, and with a booster in place, it will look even better.

OpenRocket allows you to create a kind of "artist's conception" of what the final rocket will look like in flight.
I can't wait to do a test flight!

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