Advanced Model Rocketry

You may be wondering how far you can take this sport. The answer is "a long, long ways." This page will give you a taste of some advanced techniques and enhancements to the sport. Once you've mastered the basics, you may want to take it further with some of these ideas.


Physics and Performance 

If you're mathematically inclined, you may become interested in the physics of rocket flight performance. You can delve into the calculations that take a rocket's weight, coefficient of drag, motor total impulse and thrust duration to derive the expected altitude of a given launch. You can get software that helps you with the calculations and if you have a big enough rocket to send an altimeter up, you can see how close your calculations were to reality. If that's not enough math for you, you can dust off your trigonometry tables and use them to calculate the altitude based on the angle from horizontal at known distance from the launch site.

One software package (that runs on Windows) that you can download is the Rocket Altitude Simulation Program for Windows (wRASP). This software is very powerful, allowing you to enter the key parameters for your rocket and its engine and then calculating its flight profile. It comes with specs for a few popular rockets and you can add your own by entering a few performance numbers.

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High Power Rocketry (HPR)

Model rocket engines are ranked in terms of their absolute impulse power (usually measured in Newton-seconds). The table below shows the engines and their power ratings. Once you exceed 160 N-s of total impulse in your rocket engines, you have entered the realm of high-power rocketry.

Engine Size
Total impulse (N-s) max.
Propellant mass (typical, grams)
 Certification Requirement
A
2.5
 3.5 None
B
5
 6 None
C
10
 11 None
D
20
22 None
E
40
 30 None
F
80
 46 None
G
160
 72 None
H
 320   Level 1
I
 640   Level 1
J
 1280   Level 2
K
 2560   Level 2

High power rocketry is defined as the use of models using engines larger than the "G" size. You must be at least 18 years old to purchase G-size engines or larger. Furthermore, you must have a certification to buy H engines or larger models. Thought they are not shown in the table, engine sizes actually go up to a gargantuan O size with 40,960 Newton-seconds of total impulse power. You'll need a lot more information than you'll find on this site before you launch anything close to an O-size motor.

Additionally, the Federal Aviation Administration (FAA) places restrictions on the use of model rocket engines with more than 113 grams (about four ounces) of propellant. When using engines over the limit, you must obtain an FAA waiver for the launch. These typically specify a maximum altitude for any launches covered by the waiver.

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Scale Models

A good percentage of model rocket kits you'll see are designed to be easy to build or fly incredibly well. They usually are not modeled after any particular full-size rocket. Many advanced rocketeers, looking for a new challenge, start to build scaled-down versions of real rockets and missiles. Maybe you've seen scale versions of a Saturn V or a German V-2 rocket. If you're lucky, you've even seen them launched.

A scale model of a V-2 rocket (used without permission from LOC Precision)

Scale rocketry is more challenging in a number of ways. First, the scale models tend to be more detailed than most sport rockets. This means more time in construction. It also tends to mean that research must be done, unless you're working from a pre-packaged kit. Another challenge is that the dynamics of a miniaturized model may be different than that of the full size model. It may even cause the scaled-down version to be unstable. These, and other, issues must be dealt with regularly by scale model rocketeers.

Scale rocketry is more involved than can be covered here. See the links on the resources page for more information.

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Specialties

Once rocketeers have mastered the basics of building and flying, they often are looking for the next level of challenge. Here are a few areas that offer such challenges and also some very real rewards.

Aerial photography

On mid- and large-size rockets, you often have the capability to carry a fair sized payload on the flight. Cameras are one such payload that are sometimes used to enhance a launch. These range from simple still cameras (110 sized, for example) all the way up to motion picture and even video cameras. Some video systems are capable of transmitting their image over a radio link to monitors on the ground. Go here to see a very detailed project using a video camera and transmitter system.

Payloads

Besides cameras and video equipment, there are a number of other payloads that can be sent aloft on your model rockets. Once you've gotten over the urge to launch your hamster into space (and this is highly discouraged by the NAR Safety Code) you will find that there are a number of other payloads that can be used. Many of these are electronics packages such as altimeters and location transmitters. Electronic altimeters are often used to calculate the point of apogee and to deploy the recovery system at that time.

Night launches

A few hardy hobbyists enjoy the visual effects of a night-time launch. The brightness of the flames and smoke from the engine are amplified many times in the dark. This makes for a spectacular sight (and a challenging recovery).

 Your night launch will look kind of like this, only smaller (NASA)

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