hpr-knowledge-base/hpr_transcripts/hpr2254.txt

Episode: 2254
Title: HPR2254: Introduction to Model Rocketry
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2254/hpr2254.mp3
Transcribed: 2025-10-19 00:27:18

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This in HPR episode 2,254 entitled Introduction to Modelocketry.
It is hosted by SteamCainer and in about 54 minutes long and Karima Cleanflag.
The summary is, Steam talks about the hobby of Modelocketry including some of the advanced aspects of the hobby.
This episode of HPR is brought to you by An Honesthost.com.
Get 15% discount on all shared hosting with the offer code HPR15, that's HPR15.
Better web hosting that's honest and fair at An Honesthost.com.
Hello Hacker Public Radio, my name is Steve. Today I am going to talk to you about one of my hobbies.
That hobby is Modelocketry. Last spring I did my first HPR show on how I came to Linux.
In introducing myself, I mentioned that one of my hobbies is Modelocketry and that I had hoped to do a show on that subject.
By way of Ken's reckoning, I suppose that means I owe him a show.
I've been thinking about it and trying to figure out how I want to approach it and this is what I've come up with.
So I find that when I mention to people that I'm into building and flying model rockets, most people know what I'm talking about.
In the sense that they have heard of model rockets, they may have flown a few when they were kids,
or perhaps their own kids fly some, maybe they flew rockets as part of a school project or something of that sort.
But most people, while they typically know sort of what I'm talking about, I think that most people think that it is an activity that is primarily for kids.
And certainly it can be that. But it is also a hobby that is enjoyed by many adults as well.
I know some people that have been building and flying rockets for upwards of 50 years now.
So I guess what I want to try to do with this show is to introduce some of the more advanced topics and kind of show how Modelocketry goes from being a kids activity to a serious hobby.
So to do that, I'm going to start with a little bit of history. Modelocketry, as we know, it started in the 1950s.
It was a time in history when there was a lot of rocket development, both for military purposes and scientific purposes, particularly in the United States, but in other countries as well.
Russia definitely was doing rocketry development at that time too.
And so this was the precursor to what became known as the space race between the US and the Soviet Union and the eventual evolution then of sending a man to the moon.
The interest in rocketry began to bleed over into the general public, especially to the youth.
So you may have seen the movie October Sky or read the book on which it was based named Rocket Boys by Homer Hickam, Jr.
This movie and the book gives some insight into how kids of that day started experimenting with amateur rocketry.
As it turns out, Hickam and his friends were pretty lucky and that they were able to avoid serious injury and property damage.
That was not always the case. Stories of kids losing limbs or worse started surfacing. It was a dangerous hobby to be sure.
So during this time, there was a man by the name of George Harry Stein, usually it goes by the name G Harry Stein, who he was a real rocket scientist and he worked for a while at White Sands Missile Base in New Mexico.
And for other aerospace companies as well. And he in particular began to become concerned about the interest that he saw growing in amateur rocketry given the level of danger that was involved.
So he began to think about ways to make a rocketry safer and also more accessible to the public on a hobby level.
And the key to that was to develop a model rocket motor that was safe to use. And he found another man by the name of Orville Carlyle who had also been working on this and together they essentially pioneered the model rocket motor.
Of course, the next key to this was to make the motors accessible to the public and that basically meant mass production.
So he learned about a man by the name of Vern Estes, who was manufacturing fireworks in Colorado. And he talked to him and convinced him to work on the problem of producing these model rocket motors and Estes successfully built a machine that could mass produce model rocket motors.
And the rest, as I guess they say, is history. Estes industries became synonymous with model rocketry selling motors and then later rocket kits as well.
And now even today, even though it's under different ownership and has gone through several ownership transitions, Estes is still one of the most recognized names in model rocketry.
But there's also now many other manufacturers and companies that are selling model rocketry products.
So with that little bit of history, it's probably now worth describing the basic model rocket for those listening that may not be familiar with them.
So really, the most basic model rocket starts with an airframe made of a cardboard tube at one end of the tube.
You have a nose cone that's usually made of plastic or balsa wood. And at the other end, you have some fins, usually three or four of them, but sometimes more as well.
And they also are usually made of plastic or balsa wood, sometimes cardboard.
So then you add to that the motor. The motor is a self-contained unit, kind of like a cartridge. And that is something you purchase and can be put into the rocket.
The typical Estes motor is made from a thick cardboard tube at one end of the tube is a ceramic nozzle.
And the propellant is then pressed into the tube. The primary propellant for the small rocket motors is black powder, or it's based on black powder.
The motor then is intended to be lit or started with an electrical igniter.
You push that igniter up through the nozzle until it comes in contact with the propellant.
When electrical current is applied, the igniter heats up, and there's a little bit of pyrogen on the tip that generates a small flame.
And this lights the black powder propellant.
So then the main thrust producing propellant burns for a short time, maybe one or two seconds.
And then after that comes a delay section.
And this is a material that burns, and it produces some smoke, but essentially no thrust.
The delay will burn for maybe two to six seconds, depending on which motor it is.
And then when that's done, there's another black powder charge that lights at the other end of the motor, if you will.
And that produces a quick burst of gas in the forward direction, and this is called the ejection charge.
So this motor then is inserted into the bottom end of the rocket, and it's generally held in place, either by a metal clip,
or sometimes just friction fit or taped in with some masking tape, perhaps.
So then above the motor, inside of the airframe tube, you crumple up a bit of flame retardant material that we call wadding.
And on top of that, you pack a small parachute, or a streamer.
And the parachute is usually made of plastic sheet.
The purpose of the wadding is to protect the parachute from the hot gases and the particles of the ejection charge.
The parachute then is usually tied to the nose cone, and the nose cone is then also tied to the airframe with a shock cord of some kind, either a piece of elastic or something like a rubber band type material.
And the nose then just slides onto the upper end of the airframe tube.
It is not permanently fixed.
So now the rocket is then placed on a launch pad.
The launch pad consists of a rod that is held vertically.
Typically, we use either one eighth inch diameter or a three sixteenth inch diameter rod.
That's about three millimeters to five millimeters.
Glue onto the outside of the rocket airframe is a small piece of basically what looks like a drinking straw.
We call it a launch lug, and this is what slides over the rod.
The purpose of this launch rod is to give the rocket some guidance as it starts to fly upwards.
When it reaches the end of the rod, it should be going fast enough that the fins can then do their job of providing stability with the air moving over them.
So once you have all this set up, an electrical current is provided to the igniter, this lights the motor.
It starts producing thrust, which causes the rocket to go upwards rapidly.
After a second or two of thrust, you then have the delay grain.
And at this point in time, the rocket is basically coasting.
And as it's coasting, it's slowing down.
Near the highest point of the flight, which we call Apogee, the ejection charge in the motor fires.
And this pushes the nose cone off and pushes the parachute out of the airframe.
The whole thing then floats down to a gentle landing, hopefully.
So if all goes well, the old motor can be removed and new and put in its place.
The parachute can be repacked and the rocket can be ready to fly again.
So that's essentially what G-Harry Stein and others in the 50s invented.
And we still fly rockets today that are essentially the same flight profile and same concept.
So how do you then go about building a rocket, model rocket?
Now, most people start by purchasing kits.
And they are made by companies like Estes.
And then there's others, such as Quest and Semrock, and there's many others.
I'm going to have some links in the show notes of some rocketry manufacturers in places
where you can purchase products so you can take a look there.
The manufacturers of these kits produce all shapes and sizes,
and they typically divide them into several skill levels.
Anything from a rocket that is pretty much pre-built and ready to fly
to kits that are fairly complex and take a degree of modeling skill to put together.
The tools that you need to build most kits include a hobby knife of some sort,
like a razor knife, some sort of glue
for the small rockets, anything from just an elmer's glue to a wood glue is fine.
You probably want a ruler or a straight edge of some kind.
Most people, when they, after they built the kit, like to paint their rockets before flying them,
but you certainly don't have to do that.
So then the rocket motors, as I described them, they come in several physical dimensions.
The common sizes include a 13 millimeter in diameter motor,
an 18 millimeter, and a 24 millimeter.
And so in the bottom of the rocket, regardless of the diameter of the airframe tube,
there will be a motor mounting tube that is part of the construction
that fits one of these sizes of motors.
So these motors then have designations that specify things like how much thrust they produce,
the overall power of the motor, and the delay timing, the amount of delay that's in there.
So it's important to match the appropriate motor with the given model
so that it performs as desired.
Now, I'm not going to get into the details of the motor designations in this show,
but just for reference, they are generally grouped together by total impulse or power.
And that's indicated by letters.
So for example, you have A motors, B motors, C motors, and so on.
And each letter designates a certain amount, basically a certain power range.
And the maximum power for a B motor is double the maximum power of an A motor.
Maximum power for a C motor is double that of a B motor, and so on.
So then you also have, in addition to this letter, you have an average thrust designation,
which is a number measured in Newton's.
And then finally, you have another number representing the delay time in seconds.
So some typical model rocket motors are, say, the A-8-3.
And that's usually written as an A, capital A, the number eight, a dash, and a three.
Or a B64, or a C65, and so on.
So that is a description of the basic model rocket, how it flies, how you go about building it.
So where do you go from there?
And this is what I mentioned before.
How does this activity develop into a full-fledged hobby?
So I said a bit ago that most people start by building model rocket kits.
And there's many people that are content to do that only.
I mean, they only build kits.
But one of the ways you can expand your model rocket experience is to start designing your own rockets
and building them from scratch.
So most of the kit manufacturers also make general parts available for purchase as well.
So generic body tubes, nose cones, centering rings, fin material, and so on.
And you can purchase those parts and build your own designs using them.
Or you can learn to fabricate some of your own parts.
And this can conclude any of the following.
It is possible to roll your own airframe tubes using a variety of techniques and materials.
If you have access to a wood-turning lathe, for example, you can make your own nose cones
from balsa wood stock.
You can also start scavenging for rocket parts.
Many a model rocket has been made from a cardboard mailing tube or even the tubes that make
up the middle of a roll of paper towels.
In fact, I just ordered some blueprints to something completely unrelated to rocketry.
And they came rolled up in a cardboard tube.
And I told my wife, hey, I got my blueprints today and they came inside of a rocket.
Because when I'm done with it, I will probably use it to build a rocket.
So if you start getting into this, you will find that you start looking at almost any
old piece of trash and imagine how you can make a rocket out of that.
But then you can get into using higher tech tools as well.
Many people today through maker spaces and the like have access to laser cutters.
These are great for cutting out fins, centering rings, and bulkheads.
Many people today also own or have access to 3D printers.
And certainly people will make rocket parts using 3D printers.
Add to that things like CNC machines, injection molding techniques, and the options really
are endless.
Now to design your own rocket, you do need to have some basic understanding of some aerodynamic
principles so that the rocket will be stable in flight.
And there's many rules of thumbs and techniques and calculations that have been developed
over the years and you can find those to help with that.
But in today's world, software exists as well.
And there's software that includes a computer aided design component that lets you draw
your design similar to just a generic CAD program.
But then it also includes built-in simulation algorithms.
And you can then put your design through an entire flight profile simulation.
And it will tell you what to expect in terms of velocity, acceleration, stability, various
things like that.
The two most popular software products for design and simulation of model rockets are
RockSim, which is a commercial product and it's available for Windows and OS10.
And then there's Open Rocket, which is an open source application written in Java.
And it's a Java application and it can run on Windows, OS10, Linux, and basically anything
where you have a Java runtime environment available.
And I'll have links in the show notes to both of those.
I've used both of those.
I prefer Open Rocket because it's open source and I can also run it on my Linux computers.
I also think it's actually more actively developed and overall a better product, but it hasn't
been around as long.
So a lot of people still use RockSim and swear by it.
So designing your own rockets, building them from scratch, perhaps fabricating your own
parts, is one of the ways that you can take the next step and develop the hobby of model
rocketry.
So what's another thing?
Another way to expand the hobby is to focus on craftsmanship.
And this is related, but a little bit different to what I just talked about.
As whether you're building a kit or scratch building, there are people that spend a great
deal of time and effort to make their rockets works of art as well as flyable.
And this includes adding realistic looking details.
It includes the development of painting and finishing techniques that make the rockets
beautiful as well as flightworthy.
Now related, in some ways, to craftsmanship is scale modeling.
Now, this is where the model rocket is actually a scale model of a real rocket.
And there are kits available as well as people scratch build scale models of military missiles,
sounding rockets, manned space flight rockets, and even science fiction spacecraft.
There's a lot of research available that documents the details of hundreds of rockets from
all ends of the globe and all ends of the spectrum.
And that information can be gleaned to get scale details just right.
And there's books written on the subject.
There's websites available.
If you're into that, the research of the scale data is for many people as much fun as actually
building.
I mean, it's part of the entire package.
And so then when you combine quality craftsmanship with scale modeling, you can end up with some
truly remarkable pieces of work as a result.
And indeed, there are competitions that exist for scale and craftsmanship.
And the competitors are judged on a combination of attention to scale details, quality of
craftsmanship, reproduction of specific mission details, and then finally the actual flight
of the rocket.
So speaking of competition, that's another way to expand interest in the hobby.
So in the United States, there are regional and national meets that are available, where
participants come and compete against each other in a variety of events.
There's also an international level of competition where teams from all over the world get together
and compete.
So the events that are held at these competitions include some of the following.
There's altitude events where the goal is to make your rocket fly the highest possible.
Highest you possibly can.
Usually that's for a given motor size class.
So for like A rockets using A motors, you're trying to maximize altitude, for example.
There are also duration events where the goal is to maximize the time from lift-off
to landing.
These events usually also specify a motor class and a recovery method such as B parachute.
So a rocket with a B motor using a parachute maximize the duration of the flight.
But then there's also more advanced recovery methods such as gliders, where the rocket
goes up using a regular model rocket motor like a rocket.
But then it glides down like an airplane.
There's also helicopter recovery, where at Apogee the rocket deploys some kind of propeller
like blades and auto-rotates down like a helicopter.
You also have payload events where the goal is to carry some standardized payload and
maximize either altitude or duration.
One of the most interesting competition events is egg loft.
This is where you put one or more raw chicken eggs in the rocket and the goal is to either
maximize altitude or duration depending on how the event is written up.
But also you must protect the egg from breaking.
If your egg breaks, you're disqualified.
And so that event is intended to simulate the design challenges that one faces when launching
a fragile payload such as in a manned space flight program.
So it sort of simulates that idea.
So you can use a typical model rocket kit to participate in these competition events.
But most serious competitors will design their own rockets.
And they're very carefully engineered to maximize performance, which means minimizing
weight, minimizing drag, maximizing parachute size for the given size of the rocket in
order to get the maximum amount of duration, things of that sort.
The competition is definitely a big area in model rocketry.
And it's a way to turn a simple activity into more of a serious hobby.
So then the next major category that I want to talk about is referred to as high power
rocketry.
Now high power has probably been the fastest growing aspect of model rocketry for the
last 10 to 20 years or so.
And there's a big spectrum of what high power rockets are.
In terms of definition, a high power rocket is one that uses a motor over a certain threshold
of total impulse or power.
And typically at least in the US, that means an H motor or bigger.
I told you that motors have the letter designations and each letter represents a range of power.
And the maximum of each letter is double that of the previous letter.
So you get to an H motor and that you crossed into what's generally called high power
rocketry.
So there's a spectrum of high power rockets.
One end of the spectrum, you have large rockets.
High power rockets can be upwards of one foot or more in diameter.
They can be tens of feet long and weigh in at hundreds of pounds.
In some cases, you can actually do full scale models for some of the sounding rockets or
some of the smaller missiles.
I have personally seen a one-ninth scale Saturn V. No, one-ninth scale Saturn 1B.
I think it was.
I've personally seen one of those fly.
The rocket stood, I think, 25 feet tall.
I believe it was on the order of 900 pounds that lift off.
So some people build some remarkably huge rockets.
But then at the other end of the high power spectrum are rockets that fly to very high altitudes.
There's an excess of 30 to 50,000 feet.
For reference, 50,000 feet is something like 15 kilometers.
So you have high power rockets flying to extreme altitudes.
But then in addition to high altitudes, some of them can fly supersonic as well, faster
than the speed of sound.
And rockets that will fly at speeds ranging from Mach 1 to say Mach 3 are not uncommon
at all, and sometimes even faster than that.
So the secret to any of these high power rockets is the development of composite propellant
motors.
You'll remember that I said that the basic model rocket motor uses a propellant made
from black powder.
And that works great for small motors.
The problem is, however, the black powder is pretty heavy relative to the amount of
thrust it can produce.
And at some point, to build a bigger black powder motor gets quite unwieldy.
And so you enter in the composite propellant.
These propellants are made from a combination of materials, and the most common kind of
base, if you will, is ammonium per chlorate.
Now an interesting thing about that is that that is essentially the same propellant that
was used in the solid fuel boosters for the space shuttle.
And so that's what we use in these composite motors.
Now there's additives and things that are added to the motors and the mixes are adjusted
and so on to give different thrust profiles and so on.
But composite propellant produces a lot more thrust for a given weight.
And there are several manufacturers to produce these kind of motors.
Interestingly enough, Estes is not one of those.
Estes is like king when it comes to black powder motors, but they don't do composite
motors.
The biggest names in composite motors is Arotech and Cessaroni.
Arotech is an American company, Cessaroni is a Canadian company actually.
But there are some others as well.
Now another interesting aspect of composite motors is that they come in several different
configurations.
You have single use motors that are available and they're similar to the small black powder
motors in the sense that you buy the motor as a unit, you fly it and then you throw it
away.
Usually the casings are made from plastic or fiberglass, but they're just single use one
time motors.
But then there's also what's called reloadable motor systems.
And for the reloadable motors, you purchase an aluminum casing and you use that casing
again and again.
You then purchase a propellant kit that includes the actual propellant grains, some O rings
and some seals and various things.
And you assemble that motor inside of the aluminum casing.
And once you burn it, then you have to get a new propellant kit, but you use the casing
over and over.
Now if you want to get into high power rocketry, you also have to be aware of more rules
and regulations.
And in the United States, the Federal Aviation Administration, which is the Federal Organization
or branch that regulates the airspace, there are regulations and that those regulations
require that you have a waiver filed when flying high power rockets.
And I assume that there's similar things probably in other countries as well.
But to be honest, I'm not terribly familiar with the rules in other countries.
So you definitely would want to look at what those are.
Also in the US, in order to purchase and use high power motors, you have to go through
a certification process.
And in the US, we have three levels of certification.
Each level allows you to fly larger motors.
So as you might imagine when building a high power rocket, the materials that the rocket
is built from change.
You have thicker cardboard and heavier duty plastic, as well as more advanced materials,
such as fiberglass and carbon fiber.
Plywood is often used in place of balsa wood for things like fins and other components.
So the next advancement I want to talk about in model rocketry is what I'm going to call
complex rocketry.
Now complex techniques can be found in both low and mid-powered rockets, as well as high
power rockets.
And this is where the flight profile is a bit more complex than the basic model rocket.
So one of those complexities, first thing to mention, is motor clustering.
This is where you put multiple rocket motors in the rocket at the same time and light
them all at once.
And getting all of the motors to light at once can be a bit of a challenge, especially
for the composite motors.
Black powder is a little bit easier to do that with, but it can be done on both.
The next form of complex rocketry would be staging.
This is where you light one or more motors on the launch pad, and then after they have
finished producing thrust, you light another motor or set of motors.
Two stage rockets are fairly common, but you also see three stages and more as well.
So you can get into complex motor configurations, both clusters and staging.
There's also complexities that you can add in terms of recovery.
So we talked about the basic rocket profile.
You go up to Apigee, you deploy a parachute, and it floats down.
If your rocket is going to fly to a pretty high altitude, one of the problems you run
into is that if you deploy a parachute at Apigee, it will tend to float with the wind and
drift with the wind.
And higher altitude rockets can drift for miles, which makes them hard to find.
So a concept that is often employed is something we call dual deployment.
This is where at Apigee, you deploy a small drogue parachute, and this allows the rocket
to fall rapidly and not drift very much.
And at some lower set altitude, you deploy a second, larger, main parachute.
And then this allows the rocket to land safely, but not have enough time to drift very far.
Well you might wonder how you go about doing that.
Well that brings in the next major topic of how you might advance in model rocketry,
and that is the addition of electronics.
So at the basic level, we have altimeters.
And these are available for all sizes of rockets.
They will tell you if nothing else, how high your rocket flew.
And there are a variety of commercially produced altimeters out there.
Most of them have a barometric pressure sensor and a small microcontroller, and it calculates
the altitude based on the change in atmospheric pressure as the rocket goes up.
Now some of these simply tell you how high the rocket went.
Others will also record data throughout the duration of the flight and calculate things
such as velocity and acceleration.
And this data can then generally be downloaded to a computer and displayed in one way or another.
So then in addition to altimeter, you also have flight computers that have additional sensors
that can measure things like temperature, acceleration, and even orientation.
And then these devices can also initiate one or more events.
So I described how the basic model rocket motor has a delay in it that allows the rocket
to coast to apogee before the ejection charge is fired to deploy the parachute.
When you have bigger rockets flying to higher altitudes, it becomes really difficult to rely
on a delay grain built into the motor because there's just too many variables involved.
So especially in high power rockets, you start to see altimeter systems that are used to detect
when the rocket has reached apogee and have it fire an ejection charge to deploy the recovery gear
rather than the motor.
So when the motor burns out, it's done.
And do you then rely on electronics to deploy your recovery gear?
So then that same device often has the capability to fire a second ejection charge at a lower altitude.
And that's one of the ways you implement dual deployment.
So electronics have become a huge part of rocketry, especially for things like dual deployment
and altimeters and so on.
But the next step that you get to with electronics is tracking.
And this is especially important for the high altitude flights, where the rocket is definitely
going to go out of sight.
You want to be able to track it so you can find it again.
Now tracking can be done with a simple radio beacon that you can put in the rocket.
And it can be picked up on some kind of radio using a directional antenna to determine where
the signal is coming from.
And some people definitely use those.
More sophisticated systems, however, now have GPS receivers on them.
And RF transmitters that can transmit telemetry data to a ground station.
So you can still use direction finding if you want to, but you can also pick up this data stream
and feed it into either a computer or a smartphone.
And it will tell you where your rocket is in terms of altitude, bearing, elevation, et cetera.
So then there's another aspect of electronics that a lot of people like to get into and
that involves cameras.
It's become pretty common for people to attach video cameras to their rockets to be able
to document the flight from the perspective of a passenger.
And you can find many such videos on YouTube if you go searching for them.
So that's the electronics aspect.
And like I said, there's many commercial products available that you can purchase.
You can also build your own.
People have built flight computers out of our dweenos, other microcontrollers.
It's a wide open aspect.
So the last of the advanced rocketry things I'm going to talk about today is experimental
motors.
Now, everything I've talked about so far with respect to rocket motors has been assuming
commercially produced motors that you purchase.
Many of them are single use.
Some of them require some assembly and some of them, as I said, are reloadable.
You have parts that you use again and again.
It is possible to get involved in building your own motors.
And by this, I mean actually mixing your own propellants and pouring the propellants into
molds and producing motors.
There are several different kinds of propellants that are typically used for this, but I'm not
getting into the detail of that.
It should be noted that making your own rocket motor propellant does add a layer of risk.
It can be dangerous if you don't know what you're doing.
So if you're going to do this, it's best to learn from someone else that has experience.
But beyond the danger, there's other risks as well.
Homemade motors are generally not as reliable as commercial motors.
And so the chance of a motor failing and damaging your rocket is definitely somewhat
greater.
Generally speaking, a lot of times people think that, well, if I make my own motors, I can
save money by not having to buy the motors, I can buy the components in bulk cheaper.
In the long run, I don't know that it's really any cheaper because you probably lose
more rockets, which they're expensive to, so it can go both ways.
Experimental motors are, in some ways, a departure from the fundamental problem that people
like G. Harry Stein were trying to solve back in the 50s.
He was trying to make model rocketry safer, and that meant producing a safer, reliable,
commercially-produced motor.
And so there's been controversy over the years in the community over what support should
be given to experimental motors, nonetheless, it is available for those that are interested.
So now a few other things I want people to be aware of, and that is some of the national
organizations that support the hobby.
In the United States, we have two such organizations.
We have the National Association of Rocketry, and it is the oldest of the two.
It was started in 1957 by none other than G. Harry Stein himself.
The NAR supports pretty much all aspects of model rocketry with the exception of experimental
motors.
The NAR does not support experimental motors in part because of the history coming from
G. Harry Stein.
The other US National Organization is the Tripoli Rocketry Association.
The Tripoli is focused primarily on the high-power rocketry, and it was started at least in part
due to a dissatisfaction among some people with the NAR's slow acceptance of high-power.
And so basically, as high-power motors were becoming available, the NAR, the National
Association of Rocketry, was somewhat reluctant to support that, and they kind of drug their
feet on the high-power stuff, and people got impatient with it, and that is kind of where
Tripoli came from.
Today, NAR definitely does support high-power, but not the experimental motors, and so Tripoli
focuses primarily on high-power and does support experimental motors as well.
Now one of the functions of these national associations is to develop safety codes for
model rocket flying, and they also function as an advocate for their members with regulators,
and they consult in the writing of regulation.
Part of their role is also to produce the structure for high-power certification.
So if you wish to fly high-power rockets, you must maintain a membership with one or
both of those associations, and you must follow their procedures for getting certified.
Now an important aspect of all of these roles is that the associations also provide to
their members liability insurance.
If you're a member of the NAR or Tripoli, and your rocketry activities happen to cause
damage or harm, and you're found liable, so long as you are operating within the bounds
of the relevant safety codes, your liability can be covered with that insurance.
Another role of the national organizations is to provide a framework for the establishment
of local clubs or sections, and I definitely recommend joining a local club if you're
interested in pursuing the hobby, or if there's none in your area you could even start
one.
One of the benefits of membership in a local club is simply the opportunity to learn from
other people's experiences, and it can also add to the enjoyment of the hobby to have
like-minded friends and to share those experiences.
But there's also some practical benefits to being part of a club.
One of those is that finding a place to fly your rockets can sometimes be difficult, and
often a club, particularly one that is backed by a national organization, can be more successful
in securing permission from a landowner to hold rocket launches compared to what an
individual can do.
This is also true when getting into the high-power flying.
I mentioned that the FAA in the United States requires a waiver for high-power rocket flights.
It is much easier for an organization to secure the FAA waivers necessary for a club
launch than it would be for an individual to do that.
So as I wrap up this overview, I do want to say just a little bit more about safety.
The hobby of model rocketry has an excellent safety record, despite the fact that we're
dealing with fire and herlling projectiles into the air at very high rates of speed.
There have been remarkably few incidents of serious injury or property damage.
And this is due in large part to the emphasis that is placed on adopting and adhering to
safety rules.
It's also a fulfillment of the desires of people like G. Harry Stein who wanted to make
the hobby safe and accessible to the public.
So it's in your own best interest as well as the best interest of the hobby to learn
the safety codes and to follow them.
So I hope that I've been able to show that model rocketry is more than just an activity
for kids.
And it certainly is that, but it can be so much more.
And the spectrum is wide.
There are so many different things to focus your attention on.
And you can participate in the hobby with relatively small financial or time commitment
or you can spend a great deal of time and money if you so desire.
So I'll finish by answering the question, what are my favorite aspects of the hobby?
So I have a background in engineering and computer science.
As a result, I tend to enjoy the design process almost as much as the flying part.
I tend to do more scratch building than I do kit building, although I do build some
kits.
I also enjoy fabricating as many of the rocket parts by hand as I can.
I have a wood lathe, I make nose cones.
I have gotten into doing quite a bit of fiberglassing work.
I make fiberglass nose cones.
I've laminated plywood fins with fiberglass.
I've wrapped body tubes in fiberglass.
I currently hold a level two high power rocketry certification through the National Association
of Rocketry.
And in a sense, most of my focus is probably on high power rockets, but not exclusively
so.
So I am a member of the NAR, that's where my certification is through.
I'm also a member of a local NAR chartered section or club.
And our club holds around six or seven launches each year, usually from about March through
November during the spring, summer, and fall time here.
Some of those launches are limited to low power rockets on a smaller field.
And then some of those are also at a larger field that supports high power flying.
The highest altitude I've reached with a rocket is just over 6,800 feet, which is about
2,000 meters or about 1 1 1 1 1 1 1 1 1.
The largest motor I've flown is a K motor, which produce about 500 newtons of thrust,
which is around 120 pounds of thrust or about 54 kilograms.
The rocket that I flew that in weighed about 24 pounds at liftoff.
I use a couple of different altimeters and flight computers.
One of those does have tracking features and a telemetry data link to a ground station.
So I'm currently, as I'm recording this, I'm currently preparing a project that I hope
to fly sometime in March.
And it may actually be very close to when this episode is released.
It will be, if it all goes well, it will be the largest and most complex rocket that
I have personally flown to date.
And I'm hoping to document that flight and be able to produce a show about that.
So stay tuned.
It'll probably take me a month or so after you hear this to get to that, but we'll see.
So in the show notes, I've included a number of links to manufacturers, organizations and
products that I've mentioned.
If you have any further questions, please comment or send me an email.
You will find that one common attribute of model rocketeers is we love to talk about
our hobby.
So I'd be happy to answer any questions.
You will probably recognize that a lot of what I said was United States specific in terms
of organizations and regulations and so on.
I'm just not familiar with what is out there in other parts of the world.
So if there is somebody out there that knows something about the hobby, particularly from
a different country perspective, do a follow-up show and let us know.
What things look like where you're at.
So thank you for listening.
I hope it was interesting and informative to some.
And as always, tune in next time for another exciting episode of Hacker Public Radio.
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