Frequently Asked Questions

So just what is a model rocket?

Model rockets may be models of real military or scientific research rockets, or original designs limited only by the imagination. They are constructed of a variety of materials, the most common being cardboard, balsa wood, plastic and fibreglass. They come in all shapes and sizes, from a few inches to over twenty feet!

Can they be flown more than once?

Yes, all model rockets are equipped with some kind of recovery device to bring the rocket back to earth in a safe fashion. Some small lightweight models may use a streamer made of crepe paper or mylar foil. This is ejected from the rocket at the top of its flight and creates drag, slowing the rockets descent, and making it easier to spot in the sky. The most common recovery device is a parachute, made of plastic, mylar, or ripstop nylon, which is deployed at the top of the flight (apogee), by a small explosive charge in the motor. A flameproof tissue called recovery wadding is placed around the parachute to prevent the hot gases from the ejection charge damaging the 'chute. Once the rocket is back on the ground, it is a simple matter to repack the parachute and wadding, replace the motor, and get back to the launch pad.

What makes them fly?

Model rockets are powered by miniature rocket motors. The smaller models use a disposable motor which has black powder (like that used in fireworks) for the propellant. Larger models use a different propellant called ammonium perchlorate which is very similar to the solid rocket booster fuel used in the Space Shuttle. There are single use disposable motors in this range, but many modellers use the "Reloadable Motor System" (RMS), which consists of a metal casing into which the propellant, in the form of a solid stick, is inserted. After use, the motor casing is taken to pieces and cleaned before being re-filled and used again. This system is more expensive to purchase, but works out cheaper in the long term than buying single use motors.

Can anyone fly them?

There are few restrictions on the smaller model rockets. The black powder motors can be purchased from many model and toy shops by anyone over the age of 16. The other motors mentioned above require that you have an explosives licence, and a couple of extra bits of paperwork, but these are not difficult to obtain. See our Moving up page for details.

Are they suitable for children?

Some of the easier models could quite easily be built by any child who has ever put together an Airfix kit or the like, but we always advise that an adult be around when sharp knives may be required. The Estes motors can be purchased by anyone over 16, but again we advise that an adult be around when rockets are being launched. We have been fairly lucky as far as regulations go in this country, but if people use these things in an irresponsible way, it won't be long before the powers that be start introducing all kinds of rules. So let's keep it safe and fun for everyone. A copy of the rocketry safety code is included with all our motors......read it , and abide by it.

How high do they fly?

How high do you want to go? Altitude is limited only by the size of your pocket! The Estes models will fly from 300 - 2000 feet, and larger models will go even higher. Some UK modellers have achieved altitudes of over 14000 feet.

How fast do they go?

Most of our models will travel at several hundred miles per hour - not bad for something you can build on your kitchen table! Some small UK rockets have been modified and strengthened in order to break the sound barrier which is around 760 mph at sea level, and there are now kits on the market specially designed to travel at supersonic speeds.

Are there different sizes of motors?

Yes, there are many different motors on the market, and they are all labeled in the same way. Printed on the case of every motor is an identification code which takes the form of a letter and then two numbers. For instance, C-5-3, or D-12-5. The letter refers to the specific impulse of the motor i.e. its power. Each letter is roughly twice the power of the previous one, so a D motor will have about twice the power of a C. The first number gives the average thrust of the motor in Newtons. The second number refers to to the "delay time" of the motor in seconds. When the motor is ignited, the rocket leaves the launch pad and accelerates rapidly. The motor may only thrust for a very short time, maybe less than a second, but in that time the rocket may have accelerated to several hundred miles per hour. When the propellant is burned up, the rocket continues to coast upwards, and the motor produces a smoke trail. This is caused by the slow burning of the "delay grain" inside the motor. This smoke aids tracking of the rocket which will by now be hundreds of feet in the air, and lets the rocket slow down before the "ejection charge" is fired. This is a tiny explosive charge in the top of the motor which pressurises the rocket body, blowing off the nose cone and deploying the parachute. Choosing the right delay time is important - if the delay is too short, the rocket may still be travelling at high speed when the 'chute is deployed, and the shock of the sudden opening of the 'chute may strip the lines from it, or break its mountings inside the rocket, causing it to return to earth rather faster than planned!!

Our Estes rockets use motors in the B to D range, and the Launch Pad models use D to F motors. Higher powered rocketry is still fairly new to the UK, but very popular in the USA, where motors of M and N power are regularly used - that's serious power!

How are the motors ignited?

Model rocket motors are always fired electrically, by means of a launch controller and an ignitor. The ignitor consists of a short length of wire with a tiny blob of a pyrogenic material stuck to it. This is inserted into the nozzle of the rocket motor and secured with a small plug. The two ends of the wire are attached with crocodile clips to the wires coming from the launch controller, which has a battery and a safety switch along with the actual ignition button. When the launch button is pressed, a current passes through the ignitor causing the wire to heat up, which in turn ignites the pyrogen. This short burst of flame ignites the motor.

There are several variations on the theme, including ignitors using a small black powder charge, and even the use of photographic flashbulbs, but the main idea is to allow a safe distance between the rocket motor and the operator. You should never try to light a motor by using a lighter or matches etc.......you will regret it.

Where can you fly them?

Small to medium size rockets can be flown from grassland, playing fields or wide beaches etc, but we advise seeking the permission of the landowner if flying from private land. Show them what you are up to, offer a demonstration, get them interested, and you should have no trouble. Don't fly near power lines, next to the motorway, or next door to your local airport! And if you want to keep your rockets, don't fly when it's windy, or you will be watching them float away to the next county! Model Rocketry has enjoyed an enviable safety record - let's keep it that way.