Make Rockets Down-to-Earth Rocket Science

2014·114.35 MB·English

by  Mike Westerfield

Make: Rockets
Down-to-Earth Rocket Science
Mike Westerfield
Sebastopol
Preface
Model rocketry has had a profound impact on my life, and I hope it does
on yours, too. If you are associated with education, you’ve probably
heard the term STEM tossed around. It stands for Science, Technology,
Engineering, and Math—all those skills we as a nation are trying to
promote. Model rocketry is the perfect STEM hobby. Let me share how it
changed me.
While I have always been bright, some might argue precocious, I was a
more or less average student through most of my early education. I did
well enough in science and math to be placed in the advanced classes,
but generally didn’t work hard enough to excel. The classes simply didn’t
interest me much. Who cared that a screw was an example of a wedge,
one of the basic tools? Seriously? That was science? Why would I
bother?
Around the time I turned 14, I started building and flying model rockets. I
read everything I could find on how they flew and how to make them fly
higher and faster. As a sophomore in high school, I was cruising along
with a 2.3 or 2.4 grade point average. I got interested in what I thought
was a simple problem: how high would my rockets go?
That summer I took an algebra book home. I came back the next fall and
tested out of second-year algebra. I enrolled in physics, devouring the
book, working every problem, not just the ones that were assigned. My
GPA that year was 3.7. It was 4.0 my senior year. I won an appointment
to the United States Air Force Academy, where I majored in physics.
Upon graduation, my first assignment was as the resident physicist for a
classified satellite program. I was, quite literally, a rocket scientist. Four
years later I earned an MS in physics, and finally felt I had answered that
problem I started on when I was a sophomore in high school. I could
determine how high my rockets would go to my satisfaction.
Now I’m not saying model rockets will turn every underachieving
Now I’m not saying model rockets will turn every underachieving
sophomore into a rocket scientist. Even if it would, we don’t need that
many rocket scientists! I introduced both of my daughters to model
rocketry, along with about a dozen fifth-grade classes over the years.
Neither of my daughters is a rocket scientist. One is a special education
teacher; the other is a research scientist working on cancer vaccines. My
granddaughter is seven; she has been flying rockets on and off since she
was two, and could push the launch button. She may not end up being a
rocket scientist, either, but she will still see a little more about what all
those math and science classes can be used for. At the very least, she
still likes science, and comes over to play with the toys regularly. Her
current specialty is polymers—she loves learning how they mix and react,
especially the ones that change state or swell with water.
Taking a look at my life and those of many of my friends, we got different
things from rocketry at different times in our lives. This book is written to
let you get different things out of it, too, whether you are reading it for
yourself, as a teacher or parent helping out an interested child, or as an
adult taking up a new hobby.
For younger children, say ages 8 to 15, most of the math and a lot of the
science in this book will be too advanced. Skip it. You can build and fly all
of the rockets and launchers without digging into any of the math, and
with little or no understanding of the science. After all, rockets are fun to
build and fly. This book will show you how to build solid propellant
rockets, water rockets, and air rockets. You’ll see how to build launchers
for each type of rocket and how to track them to see how high they go.
You’ll learn to build high-performance rockets that can hit 500 mph and
fly a half mile into the sky, and experience the thrill of seeing a rocket
glider roar into the air and glide safely back to earth.
As children become young adults, say ages 14 to 18, they rapidly pick up
new skills in math and science. While some of the math may still be a bit
too advanced, most isn’t. Very simple trigonometry shows how to track
the altitude of a rocket. Basic principles of physics and aeronautical
engineering explain how rockets fly and what makes them stable—or
unstable! Simple computer programs or free rocket simulators let budding
scientists safely design and build their own rockets, showing which
designs will fly well. They also do a great job of telling you how high a
designs will fly well. They also do a great job of telling you how high a
rocket will go. Most of the math, most of the science, and all of the
computer programs are well within reach for high school students. This is
the stage when browsing through the book will either answer your
questions or give you a good start on finding the answers.
Model rocketry is a hobby for a lot of adults, too. As you make your way
into college and take ever more advanced classes in calculus, physics,
electrical engineering, and aeronautical engineering, you will find fun
projects in this book. That’s when you’ll dive into the more advanced
parts of the book. Basic electrical engineering explains why launchers are
designed as they are. Computer programs and simulations combined
with aeronautical engineering help you coax the most from a particular
model rocket design. You will push beyond some of the information in
this book. Perhaps you will design your own GPS device, use high-
powered rockets to explore trans-sonic flight, build sensor packages to
track the speed and altitude of a rocket, or design control mechanisms to
keep a rocket from twisting so it is a better platform for photography—all
projects that have been worked on by members of the local rocketry club
I belong to. By now, you can handle anything in this book. It will give you
a basic understanding, although you’ll almost certainly jump off to more
advanced material in physics, math, electrical engineering, mechanical
engineering, computer science, and aeronautical engineering to satisfy
the particular projects you find interesting.
So whether you are just getting started with model rocketry or are an
experienced hobbyist looking for ways to sharpen your skills for a
contest, this book will help you reach your goals. Whether you end up
with a career in space exploration or not, you’re about to become a
rocket scientist!
Conventions Used in This Book
The following typographical conventions are used in this book:
Italic
Indicates new terms, URLs, email addresses, filenames, and file
extensions.
Constant width
Used for program listings, as well as within paragraphs to refer to
program elements such as variable or function names.
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Acknowledgments
There are a lot more people involved in writing a book than you might
expect. The author does the writing—most of it, anyway—and gets
almost all of the credit, but lots of other people contribute to the finished
book. This is my chance to thank those people for helping me look like a
literate professional who knows what he’s talking about.
Brian Jepson started off as the editor for this book, and was most
Brian Jepson started off as the editor for this book, and was most
responsible for making it happen. As with my last book, though, he
moved on. I’d check my deodorant, but we’ve never met in person. Still,
he kept up with the book despite his many other obligations, helping me
with several issues. When his time was stretched too thin by the new
Maker books label, he also found a great new editor to take over. Patrick
Di Justo patiently went through the entire book, offering sage advice,
encouragement, and more than a few helpful edits.
I also got to work with Rachel Head again, a great copyeditor who turns
my prose into consistent, grammatically correct English. She lives in
France, world famous for great cooking, and also contributed in another
way, with a slight tweak to the recipe for rocket eggs in Chapter 9. You
can thank her when your eggs are just a tad creamier.
I got to work with an amazing set of reviewers for this book. Several were
from the rocket club I belong to. Todd Kerns helped check my math and
made great suggestions throughout the book, particularly in the launcher
chapter, which went through a major revision because of his excellent
suggestions. He also built the beautiful minimum-diameter rocket that
appears in Figure 15-9. Bob Finch is one of the old hands at the club. He
reviewed a number of sections and made suggestions in several long
conversations at launches, at club meetings, and in phone calls. Tony
Lazzaro helped with several issues, especially in the launcher chapter.
Steve Lubliner, the chair of the NAR safety committee, helped improve
the book in a number of places, especially Chapters 2, 4, and 5.
The Ryan family holds an annual rocket day where they get together to
fly all sorts of rockets, including water rockets and air rockets. I’ve been
very fortunate to be invited to the recent events. The extended Ryan
family of Kenny Moreland, Kevin Ryan, and Jess Ryan Finley offered
suggestions and clarifications throughout the book. In particular, Kenny
helped get a nasty terminology error fixed, and Kevin made some great
suggestions that simplified the presentation of the electronics theory in
the launcher chapter. Both went through the entire book to find numerous
other small glitches. It’s a tedious task, but they did it well!
I was certainly no expert on water rockets or air rockets when I started
this book. Fortunately, I could lean on the expertise of several people
who were. Mike Sinclair from US Water Rockets did a careful review of
the water rocket chapters. I suppose that’s only fitting, since both the
water rocket launcher and water rocket parachute deployment system
were based on designs from the US Water Rockets website. The team of
Keith Violette and Rick Schertle developed the air rocket launcher and air
rocket glider you see in Chapter 6 and Chapter 21, and reviewed my
version to offer advice from their vast experience.
My wife Patty was amazing. She let me take over the living room with
launchers and rockets as I developed the projects for the book; went with
me to fly, photograph, and recover the rockets; and was the first person
to review each chapter—sometimes multiple times. I know a lot of you
have very happy marriages, but sorry—I have the best wife there is.
Photo Credits
Most of the photographs of space vehicles and real airplanes are from
Wikimedia Commons’s vast photo library.
Roger Smith of JonRocket.com kindly gave permission to use two photos
from his collection, Figures 20-28 and 23-48.
Marc Bonem built the flying Tardis shown in Figure 23-47, and kindly
supplied the photo of his creation.
Jim Jewell is the unofficial photographer for the Albuquerque Rocket
Society. He kindly gave me permission to use any of his photos, and I did
so on several occasions, including Figures 15-9 and 22-3..
Chapter 1. Let’s Fly Some
Rockets!
There are three basic kinds of rockets in hobby rocketry, and we’re going
to start right off by building small examples of each. Part of the reason is
for you to learn some basic concepts before moving on to bigger rockets.
Part is just to have some fun with matches, balloons, and projectiles.
The first kind of hobby rocket is the one you may have seen in hobby
stores or the local park. Solid propellant rockets burn some sort of
chemical, usually black powder in model rocketry. We’ll take a look at
solid propellant rockets using a match head as rocket fuel.
Figure 1-1. Match head, balloon, and straw rockets are simple examples of the three kinds of hobby
rocketry.