The Large Rocket

Small Rocket

Many schools operate a science week within which is often a rocket day.

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These rockets are often purchased from proprietary model manufacturers.

However the technology behind the rockets is relatively simple.

You will still have to buy the chemical rocket motors as the manufacture of these items is heavily regulated.

Boxford LTD accepts no responsibility for any use or misuse of the information held here you must make your own risk assessments and adjust the project accordingly.

You can easily find a selection of suppliers by clicking these links (Estes Industries or Quest Aerospace )

The rest of the rocket is a matter of engineering and manufacture.

The first rockets designed were based on 50mm x 600mm postal tubes.

The nose cone was manufactured out of blue polystyrene foam.

Nose Cone Boxford Lathe File - Download

The motor holder comes in two sizes depending on the motor you buy.

Small Standard Motor - Download

Large Standard Motor - Download

Motors come in a number of sizes and have a coding system on the side.

 

Anatomy of a basic model rocket engine. A typical engine is about 80mm long. 1. Nozzle; 2. Case; 3. Propellant; 4. Delay charge; 5. Ejection charge; 6. End cap

 

Blackpowder motors come in impulse ranges from 1/8A to E, although a few F blackpowders motors have been made.

The physically largest blackpowder model rocket motors are typically E-class, for black powder is very brittle. If a large black powder motor is dropped, or is exposed to many heating/cooling cycles (for example, in a closed vehicle exposed to high heat), the propellant charge may develop hairline fractures. These fractures increase the surface area of the propellant, so that when the motor is ignited, the propellant burns much more quickly than it should, producing greater than normal internal chamber pressure inside the engine. This pressure may exceed the strength of the paper case, causing the motor to burst. A bursting motor can cause damage to the model rocket ranging from a simple ruptured motor tube or body tube to the violent ejection (and occasionally ignition) of the recovery system.

Rocket motors with power ratings higher than D to E, therefore, customarily use composite propellants made of ammonium perchlorate, potassium nitrate, aluminium powder, and a rubbery binder substance contained in a hard plastic case. This type of propellant is similar to that used in the solid rocket boosters of the space shuttle and is not as fragile as black powder, increasing motor reliability and resistance to fractures in the propellant. These motors range in impulse from size D to O. Composite motors produce more impulse per unit weight (specific impulse) than do black powder motors.

Reloadable composite-propellant motors are also available. These are commercially-produced motors requiring the user to assemble propellant grains, o-rings and washers (to contain the expanding gases), delay grains and ejection charges into special non-shattering aluminium motor casings with screw-on or snap-in ends (closures). The advantage of a reloadable motor is the cost: firstly, because the main casing is reusable, reloads cost significantly less than single-use motors of the same impulse. Secondly, assembly of larger composite engines is labor-intensive and difficult to automate; off-loading this task on the consumer results in a cost savings. Reloadable motors are available from D through O class.

Motor nomenclature

Rocket motors. From left, 13mm A10-0T, 18mm C6-7, 24mm D12-5, 24mm E9-4, 29mm G40-10.

Model rocket motors produced by companies like Estes Industries and Quest Aerospace are stamped with a code (such as A10-3T or B6-4) that indicates several things about the motor.

The Quest Micro Maxx engines are the smallest at a diameter of 6mm. The company Apogee Components made 10.5mm micro motors, but those were discontinued in 2001. Estes manufactures size "T" (Tiny) motors that are 13 mm in diameter by 45 mm long, while standard A, B and C motors are 18 mm in diameter by 70 mm long. Larger C, D, and E class black powder motors are also available; they are 24 mm in diameter and either 70 (C and D motors) or 95 mm long (E motors). Some motors, such as F and G single-use motors, are 29mm in diameter. High-power motors (usually reloadable) are available in 38mm, 54mm, 75mm, and 98mm diameters.

First letter

The letter at the beginning of the code indicates the motor's total impulse range (commonly measured in newton-seconds). Each letter in successive alphabetical order has up to twice the impulse of the letter preceding it. This does not mean that a given "C" motor has twice the total impulse of a given "B" motor, only that C motors are in the 5.01-10.0 N-s range while "B" motors are in the 2.51-5.0 N-S range. The designations "1/4 A" and "1/2 A" are also used. For a more complete discussion of the letter codes, see Model rocket motor classification.

For instance, a B6-4 motor from Estes-Cox Corporation has a total impulse rating of 5.0 N-s. A C6-3 motor from Quest Aerospace has a total impulse of 8.5 N-s.

First number

The number that comes after the letter indicates the motor's average thrust, measured in newtons. A higher thrust will result in higher liftoff acceleration, and can be used to launch a heavier model. Within the same letter class, a higher average thrust also implies a shorter burn time (e.g., a B4 motor will burn longer than a B6).

Last number

The last number is the delay in seconds between the end of the thrust phase and ignition of the ejection charge. Black Powder Motors that end in a zero have no delay or ejection charge. Such motors are typically used as first-stage motors in multistage rockets as the lack of delay element and cap permit burning material to burst forward and ignite an upper-stage motor.

A "P" indicates that the motor is "plugged". In this case, there is no ejection charge, but a cap is in place. A plugged motor is used in rockets which do not need to deploy a standard recovery system such as small rockets which tumble or R/C glider rockets. Plugged motors are also used in larger rockets, where electronic altimeters or timers are used to trigger the deployment of the recovery system.

Reloadable motors

Reloadable motor cases. From left: 24/40, 29/40-120, 29/60, 29/100, 29/180, 29/240

Reloadable motors are specified in the same manner as model rocket single-use motors as described above. However, they have an additional designation which specifies both the diameter and maximum total impulse of the motor casing in the form of diameter/impulse. A reload designed for a 29mm diameter case with a maximum total impulse of 60 newton-seconds carries the designation 29/60 in addition to its impulse specification.

Motors are electrically ignited with an electric match consisting of a short length of pyrogen-coated nichrome, copper, or aluminium bridgewire pushed into the nozzle and held in place with flameproof wadding, a rubber band, a plastic plug or masking tape. On top of the propellant is a tracking delay charge which produces smoke but essentially no thrust as the rocket slows down and arcs over. When the delay charge has burned through, it ignites an ejection charge, which is used to deploy the recovery system.

Quest have also designed a makit yourself skyscope - Download

The technical term for the Quest Skyscope is "inclinometer" - we call sometimes just call it an "altitude measurer".  Either way, it's an awesome tool for estimating the altitude of static and flying objects.  With the Skyscope Inclinometer you don't need to use a plastic protractor and string - everything is built in!  This project will enable you to be able to estimate the height of static (buildings) or flying objects by simple "direct read" or by using "tangent calculation". 

There is a series of instructions on how to use the inclinometer. - Download

With a series of student worksheets - Download

Models are normally made with a single cord holding the whole thing together. Using a system known as Nose-blow recovery.

This is where the ejection charge of the motor ejects the nose cone of the rocket (usually attached by a shock cord made of rubber, Kevlar string or another type of cord) from the body tube, destroying the rocket's aerodynamic profile, causing highly-increased drag, and reducing the rocket's airspeed to a safe rate for landing. Nose-blow recovery is generally only suitable for very light rockets.

A typical hassle with parachute recovery.

The approach used most often in small model rockets, but can be used with larger rocket models given the size of the parachute greatly increases with the size of the rocket. It uses the ejection charge of the motor to deploy, or push out, the parachute or streamer. Typically, a ball or mass of fireproof paper or material is inserted into the body before the parachute or streamer. This allows the ejection charge to propel the fire-proof material, parachute, and nose cone without damaging the recovery equipment. Air resistance slows the rocket's fall, ending in a smooth, controlled and gentle landing.

1. Materials. I will use only lightweight, non-metal parts for the nose, body, and fins of my rocket.
2. Motors. I will use only certified, commercially-made model rocket motors, and will not tamper with these motors or use them for any purposes except those recommended by the manufacturer.
3. Ignition System. I will launch my rockets with an electrical launch system and electrical motor igniters. My launch system will have a safety interlock in series with the launch switch, and will use a launch switch that returns to the "off" position when released.
4. Misfires. If my rocket does not launch when I press the button of my electrical launch system, I will remove the launcher's safety interlock or disconnect its battery, and will wait 60 seconds after the last launch attempt before allowing anyone to approach the rocket.
5. Launch Safety. I will use a countdown before launch, and will ensure that everyone is paying attention and is a safe distance of at least 15 feet away when I launch rockets with D motors or smaller, and 30 feet when I launch larger rockets. If I am uncertain about the safety or stability of an untested rocket, I will check the stability before flight and will fly it only after warning spectators and clearing them away to a safe distance.
6. Launcher. I will launch my rocket from a launch rod, tower, or rail that is pointed to within 30 degrees of the vertical to ensure that the rocket flies nearly straight up, and I will use a blast deflector to prevent the motor's exhaust from hitting the ground. To prevent accidental eye injury, I will place launchers so that the end of the launch rod is above eye level or will cap the end of the rod when it is not in use.
7. Size. My model rocket will not weigh more than 1,500 grams (53 ounces) at liftoff and will not contain more than 125 grams (4.4 ounces) of propellant or 320 N-sec (71.9 pound-seconds) of total impulse.
8. Flight Safety. I will not launch my rocket at targets, into clouds, or near airplanes, and will not put any flammable or explosive payload in my rocket.
9. Launch Site. I will launch my rocket outdoors, in an open area at least as large as shown in the accompanying table, and in safe weather conditions with wind speeds no greater than 20 miles per hour. I will ensure that there is no dry grass close to the launch pad, and that the launch site does not present risk of grass fires.
10. Recovery System. I will use a recovery system such as a streamer or parachute in my rocket so that it returns safely and undamaged and can be flown again, and I will use only flame-resistant or fireproof recovery system wadding in my rocket.
11. Recovery Safety. I will not attempt to recover my rocket from power lines, tall trees, or other dangerous places.

The large rocket was designed based on 50mm x 600mm postal tubes.

Whilst the small rocket was based on the A3 postal tubes. 23mm x 300mm tubes.

The nose cone was manufactured out of blue polystyrene foam.

Large Nose Cone Boxford Lathe File - Download

Small Nose Cone Boxford Lathe Files - Download

The motor holder comes in two sizes depending on the motor you buy.

Small Standard Motor - Download

Large Standard Motor - Download

The parachute or drone is made form a bin liner (Get the cheap thin ones). Cut a single bin liner into six squares.

Using a glue gun and two pieces of 1m long string, glue the string diagonally across the corners). (Shock cord or kevlar string would be a good safety precaution if the string breaks or melts the rocket may return to the ground with speed).

Whole Chute

Attach the sting to the top of the motor housing.

The attach the wire retaining clip to the rocket motor housing (Stops motor falling back out on launch pad.)

Thread the wire through the tube and push the motor housing home.

Attach the Nose Cone. Fire proof wadding may be a better safety precaution (Available from Rocket Motor Suppliers).

Then push some wadding (Paper Towel) down the tube. This is to help stop the heat melting the chute as the motor pops the nose cone off.

Finally tie the chute to the shock cord. and fold and insert it into the tube end then fit the nose cone with all the loose string placed inside the rocket.

Build the launching system

Launchpad In 2D Draw - Download

First Steps and Testing :-

The Flash Gordon Prototype (Flew about as well as the stage models too).

The flash gordon space rocket amazed the children

in the 1940's and 50's shot in black and white (Colour Film was yet to be invented)

and watched all over the country on saturday mornings

in local cinemas. (Pre-Television) - The original low budget

theatre.