From ROCINews - Volume 1, Issue 1
A dazzling Code Red rocket zooms skyward at speeds of more than a hundred miles per hour. A few seconds later it deploys a parachute and returns gently to earth. Within minutes of touchdown, the rocket is ready to fly again. Best of all, that scenario can become as routine as it is undeniably exciting. All it takes is a basic knowledge of the fundamentals or rocket flight.
To be sure, launching a beginning model rocket like the Code Red doesn't require a graduate degree in physics, hundreds of dollars or hours of practice. Here are a few basics to help you get started in model rocketry.
Buying Your First Rocket
Model rockets range in size from a quarter inch in diameter and only a few inches long to more than six feet tall. Some rockets come already assembled Ready To Fly (RTF). Others are built from kits that you assemble using wood glue or plastic cement. Designs vary from the basic "three fins and a nose cone" (3FNC) to futuristic science-fiction space ships. There are even realistic scale models of your favorite missiles and space boosters. Many different model rocket motors power these models. Some deploy parachutes for recovery while others glide back to earth and land on a dime like the Space Shuttle.
For beginners the best value is a starter set that contains one or more model rockets, a launch pad, an electrical launch controller, recovery wadding, several model rocket motors, igniters and instructions. Starter sets often feature a rocket that is Ready To Fly, Almost Ready To Fly or a kit that requires some assembly. Starter sets can also include a basic 3FNC or a "payload" model, like an egglofter that launches a raw egg or a real working aerial camera.
Most starter sets cost from $10 to $40. All require either a 9-volt alkaline battery or four AA batteries to power the launch controller.
Model rockets are generally recommended for kids 10 years old and up; adult supervision is vital for anyone under 12. Some states have a slightly higher age limit requirement for purchase of model rocket motors (usually 14) and simple launch site permission/permit requirements (from the local fire authority).
Open up your starter set at home and read all of the instructions to learn how your particular launch system and model works. Some instructions are on the box itself – be sure to keep it! The instructions will also tell you how to prepare your recovery system properly so you can fly over and over.
Once you are familiar with your system, you are ready to pick a launch site as indicated in your instructions. Make sure you have permission from the landowner and the local fire authority, if necessary. You may want to locate a local NAR model rocket club and launch with them. They will enjoy having you join them and they'll help you when questions arise.
Make Your First Flight A Success
* Read and follow the NAR Model Rocket Safety Code and follow all state and local laws and regulations.
* Familiarize yourself with all of the launching instructions that came with your model and the motors.
* Practice folding your recovery system neatly -- never crumple it in a wad. It should fit easily into your model without forcing it.
* Parachutes open a little easier if dusted with talcum powder.
* Use enough flameproof recovery wadding to fill up a length of body tube equal in length to two or three times the rocket's diameter. It should be fluffy, not crammed in tight.
* If your launch controller instructions say to use alkaline batteries, always use fresh ones. Other batteries will not produce enough power to fire your igniters reliably.
Learn What Makes The Model Rocket Fly Straight
NASA-type rockets use moveable rocket engines or moveable fins to steer and stay on Top UK Casinos course. Model rockets do not use an active guidance system. They are designed to be stable and keep going in the direction they are pointed. They do this because they have fins at the back end, like the feathers on an arrow, which guide the fast-moving model through the air.
All objects tend to spin around their center of gravity or balance point. The fins create more surface area behind the center of gravity than in front for the air rushing by to hit. This forces the rear of the rocket to stay in the rear. A model with fins that are too small will not be stable and will fly all over the place. You can fix this by adding larger fins or by adding clay to the inside of the hollow plastic nose cone.
Because the rocket is not moving at the instant of ignition, we have to guide the model during the first few feet of flight as it builds up air speed. The launch pad has a launch rod or guide and the rocket has a launch lug that slides along the rod or guide.
How the Model Rocket Motor Works
Model rocket motors are real miniature solid-propellant rocket motors that are commercially made and tested for reliability. They contain the following parts:
* A casing to hold everything inside
* A nozzle to direct the flow of gasses produced
* Propellant (fuel, pre-mixed with oxidizer and pressed into a solid "grain"), which burns to produce huge amounts of gas.
* A delay that burns slowly after the propellant is used up, allowing the rocket to coast upward
* An ejection charge to activate the recovery system. The ejection charge blows the nose cone off of the top of the body tube in a typical model rocket and ejects a recovery system, such as a parachute or long streamer. The nose cone is connected to the body tube with a shock absorbing cord (the shock cord). Flameproof recovery wadding is installed for each flight to protect the recovery system from scorching.
* Model rockets are ignited from a safe distance using electrical igniters and a remote electrical launch controller with a removable safety key. The igniter heats up when enough electricity passes through it and this, in turn, ignites the propellant in the rocket motor.
Types of Motors
As a beginner you will want to begin with the simple disposable motors and become familiar with their characteristics before you decide if you wish to progress to more complex motor types.
Your kit instructions will list several recommended motors as well as the motor for your first flight. Use that first flight motor, which is usually lower power, to help you recover the model easily the first time and learn its flight characteristics.
Motor Designation Code
The motor designation code consists of a letter, a number, a dash and another number (and occasionally another letter that indicates special features provided by that manufacturer like small size or colored effects). Don't be confused by some motors that also have a secret manufacturing code that identifies the day they were produced (it is usually printed much smaller than the motor designation anyway).
Power Class: The letter indicates the total amount of power available in the motor class. Every time the letter increases, the power class doubles. Example: a "B" motor has twice the total power of an "A" motor, and a "C" is twice as powerful as a "B" and four times as powerful as an "A." Model rocket motors are classified from "1/4A" through "G" class.
Average Thrust: The number directly after the letter indicates the average thrust in newtons (the metric unit of force). The higher the number, the more average thrust in newtons (and the shorter the burn time of the propellant). For example, a B4 motor will thrust for twice as long as a B8 motor but it will have half the thrust.
Delay Duration: The number following the dash indicates the duration of the delay, or coast time, of the rocket. This is the time in seconds the rocket will coast without power before the recovery system is deployed.
After Launch: You will find that as soon as you use up the motors that came with your starter set you will want to buy more motors and more rockets to launch! After you've learned the basics of model rocketry, you'll be primed to scale new, greater heights.
Fred Shecter has written articles and model rocket plans for Sport Rocketry, the official magazine of the National Association of Rocketry (NAR), and Estes Model Rocket News. He has been active in model rocketry since 1970 and a NAR member since 1971. While in college studying aeronautical and astronautical engineering, Fred was a member of the MIT Rocket Society. After graduation he moved to the Los Angeles area to work for Rockwell as a structural designer for the Space Shuttle orbiters. He was a founder and is currently senior advisor with the Los Angeles Rocket Society, now known as the Southern California Rocket Association of the NAR.