Model rocket
Overview
 
A model rocket is a small rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...

 that is commonly advertised as being able to be launched by anybody, to, in general, low altitudes (usually to around 100–500 m (300–1500 ft) for a 30 g (1 oz.) model) and recovered by a variety of means.

According to the United States National Association of Rocketry
National Association of Rocketry
The National Association of Rocketry is the governing body for the sport/hobby of model rocketry in the United States. It was established in 1957 by Orville Carlisle and G. Harry Stine and is currently headed by Trip Barber. It is the oldest and largest model rocketry governing body in the...

 (NAR) Safety Code, model rockets are constructed of paper, wood, plastic and other lightweight materials.
Encyclopedia
A model rocket is a small rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...

 that is commonly advertised as being able to be launched by anybody, to, in general, low altitudes (usually to around 100–500 m (300–1500 ft) for a 30 g (1 oz.) model) and recovered by a variety of means.

According to the United States National Association of Rocketry
National Association of Rocketry
The National Association of Rocketry is the governing body for the sport/hobby of model rocketry in the United States. It was established in 1957 by Orville Carlisle and G. Harry Stine and is currently headed by Trip Barber. It is the oldest and largest model rocketry governing body in the...

 (NAR) Safety Code, model rockets are constructed of paper, wood, plastic and other lightweight materials. The code also provides guidelines for motor use, launch site selection, launch methods, launcher placement, recovery system design and deployment and more. Since the early 1960s, a copy of the Model Rocket Safety Code has been provided with most model rocket kits and motors. Despite its inherent association with extremely flammable substances and objects with a pointed tip traveling at high speeds, model rocketry historically has proven to be a very safe hobby and has been credited as the most significant source of inspiration for children who eventually become scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...

s and engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...

s.

History of model rocketry

While there were many small rockets produced after years of research and experimentation, the first modern model rocket, and, more important, the model rocket motor, was designed in 1954 by Orville Carlisle
Orville Carlisle
Orville H. Carlisle , a shoe salesman in Norfolk, Nebraska invented the hobby that would become known as model rocketry.In 1953, Orville and his brother Robert were joint owners of a shoe store on 420 Norfolk Ave...

, a licensed pyrotechnics
Pyrotechnics
Pyrotechnics is the science of using materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...

 expert, and his brother Robert, a model airplane enthusiast. They originally designed the motor and rocket for Robert to use in lectures on the principles of rocket-powered flight. But then Orville read articles written in Popular Mechanics
Popular Mechanics
Popular Mechanics is an American magazine first published January 11, 1902 by H. H. Windsor, and has been owned since 1958 by the Hearst Corporation...

 by G. Harry Stine
G. Harry Stine
George Harry Stine was one of the founding figures of model rocketry, a science and technology writer, and a science fiction author.-Education and early career:...

 about the safety problems associated with young people trying to make their own rocket engines. With the launch of Sputnik, many young people were trying to build their own rocket motors, often with tragic results. Some of these attempts were dramatized in the fact-based movie October Sky
October Sky
October Sky is a 1999 American biographical film directed by Joe Johnston, starring Jake Gyllenhaal, Chris Cooper and Laura Dern. It is based on the true story of Homer Hickam, a coal miner's son who was inspired by the launch of Sputnik 1 to take up rocketry against his father's wishes, and who...

. The Carlisles realized their motor design could be marketed and provide a safe outlet for a new hobby. They sent samples to Mr. Stine in January 1957. Stine, a range safety officer at White Sands Missile Range
White Sands Missile Range
White Sands Missile Range is a rocket range of almost in parts of five counties in southern New Mexico. The largest military installation in the United States, WSMR includes the and the WSMR Otera Mesa bombing range...

, built and flew the models, and then devised a safety handbook for the activity based on his experience at the range.

Companies

The first American model rocket company was Model Missiles Incorporated (MMI), in Denver, Colorado
Denver, Colorado
The City and County of Denver is the capital and the most populous city of the U.S. state of Colorado. Denver is a consolidated city-county, located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains...

, opened by Stine and others. Stine had model rocket engines made by a local fireworks company recommended by Carlisle, but reliability and delivery problems forced Stine to approach others. Stine eventually approached Vernon Estes
Vernon Estes
Vernon Estes , born January 4, 1930, is the founder and namesake of Estes Industries, the highly-recognized model rocket production company, headquartered in Penrose, Colorado....

, the son of a local fireworks
Fireworks
Fireworks are a class of explosive pyrotechnic devices used for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...

 maker, but Model Missiles closed due to unwise business discussions. Estes founded Estes Industries
Estes Industries
Estes Industries is a company based in Penrose, Colorado, USA that designs and builds model rocket and model aircraft engines and kits. They were the best known model rocket company during the "golden age of rocketry" in the 1970s and early 1980s, competing primarily with Centuri Engineering and a...

 in 1958 in Denver, Colorado and developed a high-speed automated machine for manufacturing solid model rocket motors for MMIk. The machine, nicknamed "Mabel", made low-cost motors with great reliability, and did so in quantities much greater than Stine needed. Stine's business faltered and this enabled Estes to market the motors separately. Subsequently, he began marketing model rocket kits in 1960, and eventually, Estes dominated the market. Estes moved his company to Penrose, Colorado
Penrose, Colorado
Penrose is a census-designated place in Fremont County, Colorado, United States. The population was 4,070 at the 2000 census. The Penrose Post Office has the ZIP Code 81240.-Geography:Penrose is located at ....

 in 1961. Estes Industries was acquired by Damon Industries in 1970. It continues to operate in Penrose today.

Competitors like Centuri and Cox came and went in America during the 1960s, 1970s, and 1980s, but Estes continued to control the American market, offering discounts to schools and clubs like Boy Scouts of America
Boy Scouts of America
The Boy Scouts of America is one of the largest youth organizations in the United States, with over 4.5 million youth members in its age-related divisions...

 to help grow the hobby. In recent years, companies like Quest Aerospace
Quest Aerospace
Quest Aerospace is a company based in Pagosa Springs, CO, USA that designs and produces model rocket kits.Quest Aerospace was founded in 1992 by Bill Stine , and produces model rocket kits for various skill levels of modelers, from the beginner to the most highly skilled. In 1995, ToyBiz acquired...

 have taken a small portion of the market, but Estes continues to be the main source of rockets, motors, and launch equipment for the low- to medium-power rocketry hobby today. Estes produces and sells Black Powder Rocket Motors

Since the advent of High-Power Rocketry, which began in the mid-1980s with the availability of G- through J-class motors (each letter designation has twice the energy of the one before), a number of companies have shared the market for larger and more powerful rockets. By the early 1990s, Aerotech Consumer Aerospace
Aerotech Consumer Aerospace
Aerotech Consumer Aerospace, established in 1982, is a company that supplies motors, kits and components for mid and high power rocketry.The company's headquarters are located in Cedar City, Utah and its products are sold mainly through US and international dealers...

, LOC/Precision, and Public Missiles Limited (PML) had taken up leadership positions, while a host of engine manufacturers provided ever larger motors, and at much higher costs. Companies like Aerotech, Vulcan, and Kosdon were widely popular at launches during this time as high-power rockets routinely broke Mach 1
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...

 and reached heights over 3,000 m (10,000 ft). In a span of about five years, the largest regularly made production motors available reached N, which had the equivalent power of over 1,000 D engines combined, and could lift rockets weighing 100 kg (221 lb.) with ease. Custom motor builders continue to operate on the periphery of the market today, often creating propellants that produce colored flame
Pyrotechnic colorant
A pyrotechnic colorant is a chemical compound which causes a flame to burn with a particular color. These are used to create the colors in pyrotechnic compositions like fireworks and colored fires. The color-producing species are usually created from other chemicals during the reaction. Metal salts...

 (red, blue, and green being common), black smoke and sparking combinations, as well as occasionally building enormous motors of P, Q, and even R class for special projects such as extreme-altitude attempts over 17,000 m (50,000 ft).

High-power engine reliability was a significant issue in the late 1980s and early 1990s, with catastrophic engine failures occurring relatively frequently (est. 1 in 20) in motors of L class or higher. At costs exceeding $300 per motor, the need to find a cheaper and more reliable alternative was apparent. Reloadable motor designs (metal sleeves with screwed-on end caps and filled with cast propellant slugs) were introduced by Aerotech and became very popular over the span of a few years. These metal containers needed only to be cleaned and refilled with propellant and a few throw-away components after each launch. The cost of a "reload" was typically half of a comparable single use motor. While catastrophes at take-off (CATOs) still occur occasionally with reloadable motors (mostly due to poor assembly techniques by the user), the reliability of launches has risen significantly. In addition, it is possible to change the thrust profile of reloadable motors by selecting different propellant designs. Since thrust is proportional to burning surface area, propellant slugs can be shaped to produce very high thrust for a second or two, or to have a lower thrust that continues for an extended time. Depending on the weight of the rocket and the maximum speed threshold of the airframe and fins, appropriate motor choices can be used to maximize performance and the chance of successful recovery.
Aerotech, Pro-38, Rouse-Tech, Loki and others have standardized around a set of common reload sizes such that customers have great flexibility in their hardware and reload selections, while there continues to be an avid group of custom engine builders who create unique designs and occasionally offer them for sale.

Precaution

Model rocketry is a safe and widespread hobby. Individuals such as G. Harry Stine
G. Harry Stine
George Harry Stine was one of the founding figures of model rocketry, a science and technology writer, and a science fiction author.-Education and early career:...

 and Vernon Estes
Vernon Estes
Vernon Estes , born January 4, 1930, is the founder and namesake of Estes Industries, the highly-recognized model rocket production company, headquartered in Penrose, Colorado....

 helped ensure this by developing and publishing the NAR Model Rocket Safety Codes and by commercially producing safe, professionally designed and manufactured model rocket motors.

One of the main motivations for the development of the hobby in the 1950s and 1960s was to provide young people the opportunity to construct flying rocket models without having to engage in dangerous construction of motor units and direct handling of explosive propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...

s.

Model rocket motors



Most small model rocket motors
Rocket engine
A rocket engine, or simply "rocket", is a jet engineRocket Propulsion Elements; 7th edition- chapter 1 that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...

 are single-use engines, with cardboard bodies and lightweight molded ceramic nozzles, ranging in impulse class
Model rocket motor classification
Motors for model rockets and high powered rockets are classified by total impulse into a set of letter-designated ranges, from A , up to O as the largest...

 from fractional A to G. Model rockets generally use commercially manufactured black powder motors. These motors are tested and certified by the National Association of Rocketry
National Association of Rocketry
The National Association of Rocketry is the governing body for the sport/hobby of model rocketry in the United States. It was established in 1957 by Orville Carlisle and G. Harry Stine and is currently headed by Trip Barber. It is the oldest and largest model rocketry governing body in the...

, the Tripoli Rocketry Association
Tripoli Rocketry Association
The Tripoli Rocketry Association is one of the two major organizing bodies for high power rocketry in the United States. It was founded in 1964 in the Pittsburgh, PA region as a high school science club, integrating both rocketry and space science...

(TRA) or the Canadian Association of Rocketry
Canadian Association of Rocketry
The Canadian Association of Rocketry - L'Association Canadienne De Fuséologie is a Canadian federal not for profit self-supporting association and governing body representing amateur/model rocketeers across Canada...

(CAR). 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
Ammonium perchlorate
Ammonium perchlorate is an inorganic compound with the formula NH4ClO4. It is the salt of perchloric acid and ammonia. It is a powerful oxidizer, which is why its main use is in solid propellants...

, potassium nitrate
Potassium nitrate
Potassium nitrate is a chemical compound with the formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−.It occurs as a mineral niter and is a natural solid source of nitrogen. Its common names include saltpetre , from medieval Latin sal petræ: "stone salt" or possibly "Salt...

, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 powder, and a rubbery binder
Binder (material)
-See also:*Adhesive or Glue*Cement*Paint...

 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
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 and is not as fragile as black powder, increasing motor reliability and resistance to fractures in the propellant. These motors range in impulse
Model rocket motor classification
Motors for model rockets and high powered rockets are classified by total impulse into a set of letter-designated ranges, from A , up to O as the largest...

 from size D to O. Composite motors produce more impulse per unit weight (specific impulse
Specific impulse
Specific impulse is a way to describe the efficiency of rocket and jet engines. It represents the derivative of the impulse with respect to amount of propellant used, i.e., the thrust divided by the amount of propellant used per unit time. If the "amount" of propellant is given in terms of mass ,...

) 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-ring
O-ring
An O-ring, also known as a packing, or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a disc-shaped cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.The O-ring...

s and washer
Washer
Washer may refer to:People*Mal Washer, an Australian politician*Paul Washer, a Christian preacherOther*Washing machine*Washer *Washer Method, a mathematical formula for finding volume*Washer pitching, an outdoor game...

s (to contain the expanding gases), delay grains and ejection charge
Ejection charge
Ejection charge, also called expelling charge, is a pyrotechnic composition, a type of a pyrotechnic gas generator designed to produce a small short-term amount of thrust to burst open a container and eject its content....

s into special non-shattering aluminum 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.

Motors are electrically ignited with an electric match
Electric match
An electric match is a device that uses an externally applied electric current to ignite a combustible compound.-Use:Electric matches can be used in any application where source of heat is needed at a precisely controlled point in time, typically to ignite a propellant or explosive...

 consisting of a short length of pyrogen-coated nichrome
Nichrome
Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various...

, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, or aluminum bridgewire
Bridgewire
A bridgewire, bridge wire, or hot bridge wire is a relatively thin resistance wire used to set off a pyrotechnic composition serving as pyrotechnic initiator. By passing of electric current it is heated to a high temperature that starts the exothermic chemical reaction of the attached composition...

 pushed into the nozzle
Nozzle
A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....

 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
Smoke composition
A smoke composition is a pyrotechnic composition designed primarily to generate smoke. Smoke compositions are used as obscurants or for generation of signaling smokes. Some are used as a payload of smoke bombs and smoke grenades.-Obscurants:...

 but in essence no thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....

, as the rocket slows down and arcs over. When the delay charge has burned through, it ignites an ejection charge
Ejection charge
Ejection charge, also called expelling charge, is a pyrotechnic composition, a type of a pyrotechnic gas generator designed to produce a small short-term amount of thrust to burst open a container and eject its content....

, which is used to deploy the recovery system.

Motor nomenclature

Model rocket motors produced by companies like Estes Industries
Estes Industries
Estes Industries is a company based in Penrose, Colorado, USA that designs and builds model rocket and model aircraft engines and kits. They were the best known model rocket company during the "golden age of rocketry" in the 1970s and early 1980s, competing primarily with Centuri Engineering and a...

 and Quest Aerospace
Quest Aerospace
Quest Aerospace is a company based in Pagosa Springs, CO, USA that designs and produces model rocket kits.Quest Aerospace was founded in 1992 by Bill Stine , and produces model rocket kits for various skill levels of modelers, from the beginner to the most highly skilled. In 1995, ToyBiz acquired...

 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 "¼A" and "½A" are also used. For a more complete discussion of the letter codes, see Model rocket motor classification
Model rocket motor classification
Motors for model rockets and high powered rockets are classified by total impulse into a set of letter-designated ranges, from A , up to O as the largest...

.

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 B6 motor will not burn as long as - but will have more initial thrust than - a B4). Motors within the same letter class that have different first numbers are usually for rockets with different weights. For example, a heavier rocket would require a engine with more initial thrust to get it off of the launch pad, whereas a lighter rocket would need less initial thrust and would sustain a longer burn, reaching higher altitudes.

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 rocket
Multistage rocket
A multistage rocket is a rocket that usestwo or more stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of or...

s 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 that do not need to deploy a standard recovery system such as small rockets that 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.

Composite motors usually have a letter or combination of letters after the delay length, indicating which of the manufacturer's different propellant formulations is used in that particular motor.

Reloadable motors

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

Model rocket recovery methods

Model and high-power rockets are designed to be safely recovered and flown repeatedly. The most common recovery methods are parachute
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...

 and streamer. The parachute is usually blown out by the engine's ejection charge, which pops off the nose cone. The parachute is attached to the nose cone, making it pull the parachute out and make a soft landing.

Featherweight recovery

The simplest approach, which is appropriate only for the tiniest of rockets, is to let the rocket flutter back to earth after ejecting the motor. This is slightly different from tumble recovery, which relies on some system to destabilize the rocket to prevent it from entering a ballistic trajectory on its way back to earth.

Tumble recovery

Another simple approach appropriate for small rockets — or rockets with a large cross-sectional area — is to have the rocket tumble back to earth. Any rocket that will enter a stable, ballistic trajectory as it falls is not safe to use with tumble recovery. To prevent this, some such rockets use the ejection charge to slide the engine to the rear of the rocket, moving the center of mass behind the center of pressure and thus making the rocket unstable.

Nose-blow recovery

Another very simple recovery technique, used in very early models in the 1950s and occasionally in modern examples, is nose-blow recovery. This is where the ejection charge of the motor ejects the nose cone
Nose cone
The term nose cone is used to refer to the forwardmost section of a rocket, guided missile or aircraft. The cone is shaped to offer minimum aerodynamic resistance...

 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.

Parachute/Streamer

The approach used most often in small model rockets, but can be used with larger rocket models given the size of the parachute
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...

 greatly increases with the size of the rocket. It uses the ejective force of the motor to deploy, or push out, the parachute or streamer. The parachute is attached to the body either directly, by means of a ripcord
Ripcord
Ripcord or rip cord may refer to:* Ripcord , the mechanism used to release a parachute* FSB Ripcord, fire support base from the Vietnam War* Ripcord , an amusement park freefall ride...

, or indirectly, when it is attached to the nose cone, which is in turn attached to the body by a ripcord. 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.

Glide recovery

In glide recovery, the ejection charge either deploys an airfoil
Airfoil
An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

 (wing) or separates a glider from the motor. If properly trimmed, the rocket/glider will enter a spiral glide and return safely. In some cases, radio-controlled rocket gliders are flown back to the earth by a pilot in much the way as R/C model airplanes are flown.

Some rockets (typically long thin rockets) are the proper proportions to safely glide to Earth tail-first. These are termed 'backsliders'.

Helicopter recovery

The ejection charge, through one of several methods, deploys helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

-style blades and the rocket autorotates
Autorotation
In aviation, autorotation refers to processes in both fixed-wing and rotary-wing aircraft. The term means significantly different things in each context....

 back to earth. The helicopter recovery usually happens when the engine's recoil creates pressure, making the nose cone pop out. There are rubber bands connected to the nosecone and three or more blades. The rubber bands pull the blades out and they provide enough drag to soften the landing.
In some rockets, the fins are used as the blades as well. In these, the ejection charge pushes a tube inside that has tabs sticking out of the rocket that hold the fins during launch. Then the tab releases the rubber band-pulled fins than pivot up into helicopter position.

Aerial photography

Cameras and video cameras can be launched on model rockets to take photographs in-flight. Model rockets equipped with the Astrocam, Snapshot film camera or the Oracle
Oracle (rocket)
Oracle is the name of a model rocket with built-in digital camera, manufactured by Estes Industries, for aerial photography. In contrast to the camera rocket Astrocam, the Oracle allows the making of a complete film of a rocket flight...

 or newer Astrovision digital cameras (all produced by Estes), or with homebuilt equivalents, can be used to take aerial photographs.

These aerial photographs can be taken in many ways. Mechanized timers can be used or passive methods may be employed, such as strings that are pulled by flaps that respond to wind resistance. Microprocessor controllers can also be used. However, the rocket's speed and motion can lead to blurry photographs, and quickly changing lighting conditions as the rocket points from ground to sky can have an impact on video quality. Video frames can also be stitched together to create panoramas. As parachute systems can be prone to failure or malfunction, model rocket cameras need to be protected from impact with the ground.

There are also rockets that shoot short digital videos. There are two widely used ones used on the market, both produced by Estes: the Astrovision and the Oracle. The Astrocam shoots 4 (advertised as 16, and shown when playing the video, but in real life 4)seconds of video, and can also take three consecutive digital still images in flight, with a higher resolution than the video. It takes from size B-6-3 to C-6-3 Engines. The Oracle is a more costly alternative, but is able to capture all or most of its flight and recovery. In general, it is used with "D" motors. The Oracle has been on the market longer than the Astrovision, and has a better general reputation. However, "keychain cameras" are also widely available and can be used on almost any rocket without significantly increasing drag.

There are also experimental homemade rockets that include onboard videocameras, with two methods for shooting the video. One is to radio the signal down to earth, like in the BoosterVision series of cameras. The second method for this is to record it on board and be downloaded after recovery, the method employed by the cameras above (some experimenters use the Aiptek PenCam Mega for this, the lowest power usable with this method is a C or D Motor).

Instrumentation and experimentation

Model rockets with electronic altimeters can report and or record electronic data such as maximum speed, acceleration, and altitude. Two methods of determining these things are to a) have an accelerometer and a timer and work backwards from the acceleration to the speed and then to the height and b) to have a barometer onboard with a timer and to get the height (from the difference of the pressure on the ground to the pressure in the air) and to work forwards with the time of the measurements to the speed and acceleration.

Rocket modelers often experiment with rocket sizes, shapes, payloads, multistage rocket
Multistage rocket
A multistage rocket is a rocket that usestwo or more stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of or...

s, and recovery methods. Some rocketeers build scale models of larger rockets, space launchers, or missiles.

High-power rocketry

As with low-power model rockets, high-power rockets are also constructed from lightweight materials. Unlike model rockets, high-power rockets often require stronger materials such as fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

, composite material
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...

s, and aluminum to withstand the higher stresses during flights that often exceed Mach 1 (340 m/s) and over 3,000 m (10,000 ft.) altitude.

High-power rockets are propelled by larger motors ranging from class H to class O. Their motors are almost always reloadable rather than single-use in order to reduce cost. Recovery and/or multi-stage ignition may be initiated by small on-board computers, which use an altimeter or accelerometer for detecting when to ignite engines or deploy parachutes.

High-power model rockets can carry large payloads, including cameras and instrumentation such as GPS units.

The NAR and the TRA successfully sued the US Bureau of Alcohol, Tobacco, Firearms and Explosives
Bureau of Alcohol, Tobacco, Firearms and Explosives
The Bureau of Alcohol, Tobacco, Firearms and Explosives is a federal law enforcement organization within the United States Department of Justice...

(BATFE) over the classification of Ammonium Perchlorate Composite Propellant
Ammonium Perchlorate Composite Propellant
Ammonium perchlorate composite propellant is a modern solid rocket propellant used in both manned and unmanned rocket vehicles. It differs from many traditional solid rocket propellants such as black powder or Zinc-Sulfur, not only in chemical composition and overall performance, but also by the...

(APCP), the most commonly used propellant in high-power rocket motors, as an explosive. The March 13, 2009 decision by DC District court judge Reggie Walton
Reggie Walton
Reggie Barnett Walton is a federal judge on the United States District Court for the District of Columbia.-Early life and education :...

 removed APCP from the list of regulated explosives, essentially eliminating BATFE regulation of hobby rocketry.

See also

  • Amateur rocket motor classification
    Amateur rocket motor classification
    Motors for model rockets, high powered rockets, and amateur rockets are classified by total impulse into a set of letter-designated ranges, from A , up to O as the largest...

  • Amateur rocketry
    Amateur rocketry
    Amateur rocketry, sometimes known as amateur experimental rocketry or experimental rocketry is a hobby in which participants experiment with fuels and make their own rocket motors, launching a wide variety of types and sizes of rockets...

  • High-Power Rocketry
  • Model aircraft
    Model aircraft
    Model aircraft are flying or non-flying models of existing or imaginary aircraft using a variety of materials including plastic, diecast metal, polystyrene, balsa wood, foam and fibreglass...

  • Model Rocketry (magazine)
    Model Rocketry (magazine)
    Model Rocketry was an American hobbyist magazine published from October 1968 to February 1972. The Editor and Publisher was George Flynn and the Managing Editor was Gordon Mandell. The magazine was owned by the editorial staff and the paid circulation reached 15,000 by 1970.The launch of Sputnik in...

  • Rocket Festival
    Rocket Festival
    A Rocket Festival is a merit-making ceremony traditionally practiced by Ethnic Lao people throughout much of northeast Thailand and Laos, by numerous villages and municipalities near the beginning of the rainy season...

  • Thermalite
    Thermalite
    Thermalite a specific type of fuse used in pyrotechnic applications.This fuse is used in high-power model rocketry as a means of simultaneously igniting multiple "clustered" rocket motors...

  • Water rocket
    Water rocket
    A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel—the engine of the rocket—is usually a used plastic soft drink bottle. The water is forced out by a pressurized gas, typically compressed air...


External links

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