Basic Rocketry FAQ

If you are thinking you might be interested in this hobby or you are a brand new rocketeer, you probably have many questions. This page will help answer some of the questions that are asked by aspiring rocketeers. See our other FAQ’s for more information.

Q. Is this hobby safe?
A. Absolutely! According to model rocket manufacturer Estes, there have been over 300 million safe launches of model rockets in the U.S. since the sport started getting popular. There are a number of factors that contribute to this excellent safety record:
You don’t have to build your own motors or handle hazardous fuel. You can buy inexpensive, reliable single-use motors that will propel your rockets to amazing heights.
Safety in materials – modern models are constructed using only lightweight materials such as balsa, cardboard, and plastic.
Safety systems – today’s electronic launch controllers use safety keys to prevent a launch when you don’t expect one. If you follow some basic procedures there is very little that can go wrong. The rockets use recovery systems, such as parachutes, so once they’ve been fired they are returned safely to the ground.
Organizations that promote safety – The National Organization of Rocketry (NAR) has created a safety code that its members agree to follow that will maximize their enjoyment and protect them. For higher power rockets both NAR and Tripoli national organizations have special safety codes for those rockets as well.

Q. How long has model rocketry hobby been around?
A. In the U.S., model rocketry really got its start in the late 1950’s. Rocketry and space travel were very much on the minds of people in the era of Sputnik and Project Mercury. Many wanted to share in this by building and flying rockets of their own. To avoid the dangers of unskilled hobbyists handling black powder or other dangerous substances, several experts got together and developed safe and reliable motors that could be purchased commercially. We now have rigorous standards that define how these motors are manufactured and used. Today’s hobby is as safe as any if you follow some basic safety guidelines in the construction and launching of your models.

Q. What does it cost to get started?
A. You can get your start in this hobby with a small investment. Most hobby shops, toy stores, and even some department stores have complete starter kits, many of which cost less than $40. A starter kit will usually have a model rocket (some are even pre-assembled), a launch pad with launch rod, the electrical ignition system (with safety key), motors, igniters, and anything else you might need to launch your first rocket.

If you fly with a club, such as ours, that already has launch pads and an ignition system, you can get started for even less money. In this case, you can go and purchase a kit, assemble it, and use the club’s launch equipment to get it off the ground. Kits start as low as $6 or $7 and a package of three motors is usually around $5 or $6. This is a good way to go if you’re not quite sure if the hobby is for you and don’t want to make too large an investment until you know more about it.

Of course, if you’re pretty sure this sport is for you, you can also spend more on your starter set to get higher quality and equipment that will work for you if you decide to build and fly larger rockets. These starter sets are priced in the range of $80 to $200 in most cases. They typically include larger rockets and the launch equipment is usually more rugged. Check our links page for vendors to get an idea of what these kits are about and how much they’ll cost you.

Q. What are the appropriate ages for someone interested in rocketry?
A. As has already been mentioned, the hobby is a safe one as long as some basic rules are observed. If you’re twelve or younger, you’ll probably want to get the help of an adult. Building a model rocket is not difficult, but you do need to follow instructions closely and it helps to have someone with some experience looking over your shoulder. If you don’t have an adult handy, you can always contact us and come to a meeting or launch and ask for some assistance. Most members will be happy to share what they know and get you off to a strong start in your new hobby.

Q. How high does a model rocket go?
A. Typical beginner rockets will travel as high as 300 to 1000 feet (100 to 330 meters). Advanced (high power) models commonly go higher than 5,000 feet (2300 meters), with some going much higher. The altitude of a flight depends mainly on the rocket design, weight and the engine used for the launch. Keep in mind that the higher a rocket goes, the larger launch site you’ll need to make sure that you get it back after it returns to earth. Which is another reason it is good to fly with a club like ours. Our launch site is a sod farm, lots of area to fly from.

Q. What do the rocket motor letters and numbers mean?
A. This is an easy code to provide complex information. Here’s the bare minimum needed to start with:

A sample engine code might be: C63

The impulse or ‘power’ range of an engine is indicated by the letter, in this case a ‘C’. Codes start with ‘A’ and keep going up the alphabet, with each letter indicating twice the impulse of the preceding letter. So B is twice as powerful as A, C is twice as powerful as B (and 4 times more powerful than A), and so on. This is overly simplified, but you’ll absorb the details as you gain experience. Bigger engines (higher letters) achieve higher altitudes, or lift heavier rockets.

The ‘6’ is the average thrust of the engine as measured in ‘newtons’. A newton is about 1/4 pound force. So 6 newtons is about a pound and a half of thrust, but don’t worry about it for now. Just keep in mind that a ‘6’ has a higher average thrust than a ‘4’.

The ‘-3’ is the delay, measured in seconds. This means that 3 seconds (more or less) after propellant burnout, the ejection charge fires. That deploys your recovery system.

There are ‘-0’ engines. These are booster engines designed for the lower stages of multi-staged rockets. As soon as burnout occurs, the hot gases from the booster engine ignite the next engine. Don’t use these on a single stage rocket or the upper stage of a multistage rocket since they have no ejection charge to deploy a recovery system.

‘-P’ engines are plugged, and also have no ejection charge. They’re made for gliders or rockets that have some other means of deploying the recovery system. Since they are plugged they cannot be used as a lower stage of a multistage rocket unless you have provided some other means of igniting the upper stage.

Some engines have letters following the delay time, for example, A10-3T or G33-4J. This is a code that is manufacturer dependent. Some use it to indicate the diameter of the motor, others use it to indicate a different type of fuel.

We have a on-line demonstration of how a rocket motor works, if you would like to learn more.

Q. How do the recovery systems work?
A. If you spend time to get your rocket looking good, and to fly well, you’d hate to lose it! Recovery is one thing that keeps this hobby from being glorified fireworks. There are many ways to recover a rocket. Here are the most common:

Featherweight – for the lightest rockets. They have such a high surface area compared to their weight that they almost ‘float’ to the ground, like the name says.

Tumble – for very light rockets that are too stable for featherweight recovery. Usually the nose cone is ejected (it’s connected to the rest of the rocket by a shock cord), and the whole thing comes down. If something wasn’t done to ruin the stability, it might come down like a dart. At best, hitting the ground like that could damage or destroy the rocket. At worst, it could hit and hurt someone. There are terms for rockets that accidentally come down hard, they’re called Prangs or Lawn-Darts. No fun, and very hard on the rocket.

Streamer – this is a long, thin piece of plastic or crepe paper. It creates enough drag to bring the rocket down gently. These are good for days when the wind causes too much drift in a parachute. But also note that if it is a heavy rocket, a streamer will not slow it down enough to keep it from causing damage.

Parachute – these range in size from 8″ up to 24″ for model rockets, considerably larger for high power rockets. To minimize drift, you can cut a spill hole in the center of the canopy. This will help the rocket come down faster, but it hits harder when it reaches the ground. If you cut a spill hole, don’t cut it too small because a small hole can actually increase the lift the parachute generates as it descends. Estes parachutes have a spill hole marked with dotted lines, just cut it out if needed. Another technique to minimize time in the air is to ‘reef’ the shroud lines. Take a piece of masking tape and wrap it around all the parachute lines about halfway between the rocket and the canopy. This prevents the parachute from opening fully.

Glider – It goes up like a rocket, and comes down like a airplane. Really cool.

Helicopter – Ever see a maple seed fall? Spinning on one wing is one method of helicopter recovery. Another is to have rotors deploy at ejection, causing the whole rocket to rotate.

Q. What is the difference between Model Rocketry and High Power Rocketry?
A. ‘Model’ and ‘high power’ are terms which have many definitions, depending to whom you are speaking. In this case, we will use the definitions accepted by the National Association of Rocketry, and Tripoli High Power Rocketry Association.

‘Model rockets’ are rockets that weigh less than 1500 grams (3.3 pounds), contain less than 125 grams (4.4 ounces) of total fuel, have no individual motor with more than 62.5 grams (2.2 ounces) of fuel or more than 160Ns (36lbs) of total impulse. (Basically motors up through the G range.) They use only pre-manufactured, solid propellant motors, and do not use metal body tubes, nose cones or fins. Typically these would be Estes type rockets.  Sometimes you will hear the term ‘Mid-power rockets’.  This usually refers to rockets powered by E, F, and G engines.

‘Large Model Rockets’ is a term used by the FAA. It refers to model rockets that are between 454 and 1500 grams (1 to 3.3 pounds) total liftoff weight and contain more than 113 grams (4 ounces) but less than 125 grams (4.4 ounces) of total fuel. Few rocketeers use this term.

‘High power rockets’ are rockets that exceed the total weight, total propellant or single motor total impulse restrictions of model rockets, but otherwise conform to the same guidelines for construction materials and pre-manufactured, commercially made rocket motors. (In a nutshell, any motor of H power or above.) High power rockets also allow the use of metal structural components where such a material is necessary to insure structural integrity of the rocket. High power rockets have no total weight limits, but do have a single motor limit of no more than O power (40,960NS [9200lbs] maximum total impulse) and have a total power limitation of 81,920NS (18,400lbs) total impulse.

‘Amateur’ rockets covers all other non-professional rockets that do not meet the criteria for model or high power rockets. This includes metal bodied rockets, liquid fueled rockets, and rockets with any type of homemade rocket motor. Our club does not fly any ‘Amateur’ rockets at club launches.

Another term that has no formal definition but is more and more being used today is ‘hobby rocketry’. This term includes both model and high power rockets, but excludes amateur rockets. The term ‘consumer rocketry’ has also been used, and means the same thing.

The term ‘non-professional rocketry’ encompasses all forms of model, high power and amateur rocketry.

Q. Could you recommend a book or something to learn more?
A. Some very good books are:

The Handbook of Model Rocketry by G. Harry Stine.
Model Rocket Design and Construction by Tim Van Milligan.

They can be usually be found in your local library.  The first book is also sold by the NAR. The second book is available from Apogee Components. Apogee has a complete line of educational rocketry publications, including 69 Science Fair Projects with Model Rockets: Aeronautics.

A good website to learn more is Apogee Components.