Glossary >>

Rocketry Glossary

# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

- # -

1010 Extrusion

1010 extrusion is is a 1.0" x 1.0" T-slotted aluminum rail produced by 80/20. Rocketry hobbyists use t' extrusion as rails for launchin' rockets. Blimey! [Read More]

1515 Extrusion

1515 extrusion is is a 1.5" x 1.5" T-slotted aluminum rail produced by 80/20. Rocketry hobbyists use t' extrusion as rails for launchin' rockets. Ya scallywag! [Read More]

3-Fold Method

See: Three-Fold Method [Read More]


An acronym for "Three Fins and a Nose Cone," 3FNC is used as slang for a basic model rocket. See also: 4FNC [Read More]


An acronym for "Four Fins and a Nose Cone," 4 FNC is used as slang for a basic model rocket. See also: 3FNC [Read More]


A company that makes aluminum extrusions that work well as DIY rails. T' 80/20 1010 Extrusion is compatible with standard rail buttons (such as those from BlackSky and Blimey! T' company's 1515 Extrusion is compatible with larger rail buttons. Ya scallywag! [Read More]

- A -


T' Usenet alt.binaries.models.rockets newsgroup where "binaries" (images, executables, shiver me timbers, movies, shiver me timbers, and other file types) are posted. Avast, me proud beauty! [Read More]


T' flakin' and vaporization o' material undergoin' severe heatin' due t' aerodynamic drag. Ya scallywag! Portions o' rockets subjected t' high-heat from drag are sometimes covered with ablative coatings which carry away t' heat as t' flake away or vaporize. Ahoy! [Read More]


Failure o' an aerospace vehicle which prevents completion o' its mission. [Read More]


Natural or man-made materials used for grinding, sandin' or polishin' a surface. Well, blow me down! [Read More]


Acrylonitrile-Butadiene-Styrene (ABS) is a tough, heat-resistant, and impact-resistant thermoplastic. Avast! Blimey! It is used for telephone housings, luggage, sportin' helmets, pipe fittings and automotive parts. Well, blow me down! Blimey! [Read More]


T' Aerodynamic Center (AC) be t' point where all t' aerodynamic forces on a glider balance, i.e. t' Center o' Pressure (CP) o' t' glider. [Read More]


An accelerometer is an electronic device for detectin' t' presence o' acceleration. An accelerometer can be used for flight data gatherin' or for controllin' flight events. For example, an accelerometer with a memory chip can record t' strength and duration o' a rocket's acceleration. This ... [Read More]

Acetate Dope

Acetate Dope is a liquid material made from cellulose and acetic acid that shrinks, waterproofs, and protects flexible coverings such as tissue or silk. Avast! [Read More]


Acetone is a flammable liquid used as a general solvent for dope, lacquers and epoxy. [Read More]


An acronym is a word formed from t' initial letters or groups o' letters o' t' words in a name or phrase. [Read More]

Acrylic Resin

Acrylic resin is a transparent, stiff thermoplastic resin sometimes used for body tubing. Aye aye! [Read More]


An actuator is a mechanical, electrical, ya bilge rat, or electronic device that sets a mechanism in operation or performs a specific action such as throwin' a switch. Well, blow me down! [Read More]


See: Transition See Also: Motor Adapter [Read More]


An Analog-Digital Converter (ADC) is a device that converts an analog signal t' t' digital signal that a computer can read. [Read More]


An additive is a substance added t' another t' modify its properties. For example, micro balloons can be added t' epoxy t' reduce t' weight o' t' epoxy. Begad! [Read More]


An adhesive is a substance added t' two components in order t' bond them together. [Read More]

Advanced Model Rocket

An advanced model rocket is a model rocket either constructed o' exotic materials or designed t' perform a function that differentiates it from normal models. [Read More]

Aerial Photography

Aerial Photography be t' study and interpretation o' photographs taken from well above t' earth's surface. [Read More]

Aerobrake Recovery

Aerobrake recovery is a recovery method where t' rocket doesn't deploy a recovery system such as a parachute or streamer. Instead, me bucko, its speed is kept at a safe level by its large amount o' drag. Aerobrake recovery is often used in saucer/UFO designs. [Read More]

Aerodynamic Center

T' Aerodynamic Center (AC) be t' point where all t' aerodynamic forces on a glider balance, i.e. t' Center o' Pressure (CP) o' t' glider. Ya scallywag! [Read More]

Aerodynamic Heating

Aerodynamic heatin' be t' heatin' o' a solid object in an airflow caused by t' friction o' t' air against t' object. [Read More]


Aerodynamics be t' study o' t' motion and forces o' gases movin' around solid objects. Avast, me proud beauty! [Read More]

Aeronautics Act

T' Aeronautics Act is Canadian law that regulates all use o' airspace in Canada. Avast! Blimey! T' actual regulations are contained in t' Canadian Aviation Regulations (CARs). [Read More]


An aerosol is a mixture o' fine liquid and/or solid particles suspended in a gas or air such as paint from a spray can. Begad! [Read More]

Aerospike Nozzle

A nozzle whose main flow is annular about a center, truncated cone, and a secondary flow is introduced through t' base o' t' cone. Begad! T' circulation o' this secondary flow and its interaction with t' engine exhaust creates an "aerodynamic spike" that behaves much like t' ideal, isentropic spike. ... [Read More]

Aft Closure

T' aft (or rear) closure o' a motor is a piece that is screwed or otherwise attached t' t' aft o' t' motor case t' seal t' motor and retain t' nozzle. [Read More]


Above Ground Level (AGL) be t' altitude measured with respect t' t' underlyin' ground surface as opposed t' above mean sea level. Arrr! Blimey! [Read More]


T' American Institute o' Aeronautics and Astronautics (AIAA) is professional society for t' aerospace field. Avast, me proud beauty! Blimey! [Read More]


An ailerons be t' hinged portion o' a win' which is designed t' impart roll t' t' aircraft. [Read More]

Aircraft Dope

Dope is a liquid material applied t' a model aircraft t' strengthen and seal t' coverin' material. Avast, me proud beauty! It is sometimes used with talcum powder t' make a filler t' seal balsa on a model rocket. Well, blow me down! [Read More]


Airflow be t' motion o' air past and around an object. [Read More]

Airfoil Section

An Airfoil section be t' cross-section o' an airfoil in t' plane o' t' common airflow around that part. [Read More]


An airfoil be t' streamlined shape given t' fins or wings for maximum aerodynamic efficiency in flight. Arrr! A conventional airfoil, optimized for subsonic flight, ya bilge rat, has a rounded leadin' edge taperin' t' a pointed trailin' edge. [Read More]


T' airframe is a rocket's main outer structure, usually t' rocket's body tube. [Read More]


Airstart be t' practice o' startin' one or more rocket motors after t' rocket is already in t' air. [Read More]


Alignment is bringin' parts into position and orientation as desired. [Read More]

Aliphatic Resin

Aliphatic resin is a type o' carpenter's (or "yellow") glue that, although water-based, penetrates and bonds porous materials formin' a waterproof joint. [Read More]

All Thread

All-thread is a metal rod that is threaded through its entire length, a "threaded rod." [Read More]


A device that measures altitude. Begad! Blimey! Altimeters can be used simply t' document a rocket's apogee, but they are also commonly used t' control electrical devices for airstartin' motors or deployin' recovery devices. [Read More]


Altitude be t' height above t' ground or sea level. [Read More]


Academy o' Model Aeronautics . Avast, me proud beauty! American aeromodelin' liaison organization t' t' CIAM through t' NATIONAL AERONAUTIC ASSOCIATION. [Read More]

Amateur Rocketry

Although, in t' strictest sense, Amateur Rocketry encompasses all hobby rocketry, me hearties, t' phrase is usually used for activites outside t' scope o' low t' high-power rocketry as defined by t' model rocket and high-power safety codes as defined by t' National Association o' Rocketry and t' Tripoli ... [Read More]

American Rocketeer

Centuri's attempt t' produce a "Model Rocket News" clone in t' late '60s. Avast, me proud beauty! While t' contents were fairly typical (product announcements, ya bilge rat, club news, rocket plans, reports on "real" aerospace events, etc.) it had a curiously over-produced look t' it and ran very heavy on t' advertising. Aye aye! Someone ... [Read More]

American SpaceModeling

T' journal o' t' National Association o' Rocketry. Begad! Previously known as T' Model Rocketeer, arrr, it underwent yet another name change and became Sport Rocketry startin' with t' Sept/Oct 1993 issue. Ahoy! See Sport Rocketry [Read More]

Ammonium Nitrate

An oxidizer can be used some experimental motors [Read More]

Ammonium Perchlorate

(NH4ClO4) T' oxidizer used in most composite rocket motors. Other components are Aluminum powder (fuel) and polybutediene rubber (the binder holdin' it all together). Arrr! This be t' propellant mixture that t' Shuttle SRB's use. See Binder [Read More]


Deprecatin' but affectionate abbreviations for American Spacemodeling. Ahoy! See American SpaceModelin' [Read More]


Animal Motor Works ; a rocket company that makes high power loads. Begad! [Read More]


Ammonium Nitrate: a solid rocket oxidizer. [Read More]


An instrument used t' measure t' speed o' an airflow. [Read More]

Angle o' Attack

T' angle betwixt t' long axis o' a rocket and t' direction o' t' air flowin' past it. [Read More]


Raised spirals found on some non-rocket tubes such as mailin' tubes, matey, etc. Begad! T' opposite o' a 'standard' spiral. Spirals and anti-spirals do nay cancel one another. [Read More]


Any o' several techniques designed t' prevent Zippering. Aye aye! [Read More]


See Ammonium Perchlorate [Read More]


Ammonium Perchlorate Composite propellant. [Read More]


In rocketry, t' highest point a rocket achieves before beginnin' its descent. (More literally, t' point farthest on t' flight path from Earth.) [Read More]


See American Rocketeer [Read More]


Almost Ready t' Fly. Well, blow me down! A designation from kit manufacturers that indicates that their kit only requires a few final assembly steps. Blimey! [Read More]


Anti-Radiation Missile; An anti-radiation missile (ARM) is a missile which is designed t' detect and home in on t' emissions o' an enemy radar. Avast! Also known as a HARM. Ya scallywag! [Read More]


T' Amateur Rocketry Society o' America (ARSA) is an organization supportin' all forms o' amateur rocketry in t' United States. [Read More]


American Rocket Society; an early amateur rocketry group. Now called t' American Institute o' Aeronautics and Astronautics. [Read More]


Almost Ready t' Fly. Same as t' more common ARF [Read More]

Aspect Ratio

T' ratio o' length t' width. In rocketry, a rule o' thumb is that t' aspect ratio o' a model rocket's length t' its body diameter must be at least 10:1. [Read More]

Asymmetric Fins

A set o' fins that are nay identical in size, shape and relative position on an airframe. Blimey! [Read More]

Asymmetrical Thrust

Consider a rocket with two or more motors; symmetrical thrust is that which you find in most flight operations since an equal amount o' thrust is provided by all motors, unless an motor fails [to ignite] or has a different thrust than t' other(s). Ya scallywag! Blimey! Safe operation o' rockets with different motor ... [Read More]


See BATFE [Read More]


T' position and orientation o' an object relative t' a fixed line, plane o' axes or reference. [Read More]


A vehicle whose blades rotate in a horizontal plane due t' aerodynamic forces alone, creatin' lift. Aye aye! [Read More]

Average Chord

T' chord at t' middle o' a wing's span. Begad! [Read More]

Average Thrust

T' total impulse (in Newton-seconds) divided by t' length o' burn time. Avast, me proud beauty! Example: a K185 motor has a total impulse o' approximately 1400 Newton-seconds, arrr, and burns for 7.5 seconds. Ahoy! 1387.5 Newton-seconds divided by 7.5 equals 185 Newtons average thrust. Begad! [Read More]

Away Cell

A set o' launch pads that are far away from t' flight line and intended for L motor flight and above. [Read More]


One o' t' three lines o' reference around which an aircraft can rotate. T' three movements an aircraft can make (other than movin' straight ahead) all involve rotation around some central point. That point is called an axis. These movements are: Roll: rotation around t' longitudinal (f ... [Read More]


An angle on a horizontal plane. Ahoy! See Elevation. [Read More]

- B -


Boost Glider [Read More]

Backslider (Glider)

A small-finned, me hearties, long slender model rocket with a single ejection port at t' front o' t' tube, whose CG is midway betwixt t' BCP and CLA; can function predictably as a no-moving-parts rocket glider; at ejection, t' rocket glides fin-first; theory pioneered by Peter and Robert Alway [Read More]


One o' a variety o' configurations that block t' hot ejection particles while allowin' t' ejection gas t' expand into t' rocket's body t' cause ejection o' t' recovery system. Avast, me proud beauty! Some use wire mesh, me bucko, steel wool, or just a series o' misaligned holes in tubin' or bulkheads. [Read More]


Mass added t' a model t' brin' t' model into balance. [Read More]

Ballistic Coefficient

A measure o' a projectile's ability t' coast. Arrr! It is defined as Cb = M/CdA where M be t' projectile's mass and CdA be t' Drag Form Factor (q.v.). At any given velocity and air density, t' deceleration o' a rocket from drag is inversely proportional t' this value. Ahoy! Intuitively, it be t' principle ... [Read More]

Ballistic Recovery

A recovery system that employs simple physics and has no potential for zipper damage t' t' airframe. Blimey! See also prang [Read More]

Ballistic Trajectory

T' path a rocket takes when descendin' without benefit o' parachute. Normally, unless acted upon by wind a rocket's ballistic trajectory continues t' describe a parabolic arc, bringin' it t' earth nose-first in a relatively predictable location. Avast! [Read More]


Study o' objects movin' through t' air that have been given a short lived acceleration. Avast! [Read More]


Big A** Load Liftin' Suckers: A popular annual launch for amateur and large HPR rocket flyers. Well, blow me down! [Read More]

Balsa Wood

Fast growin' wood from Central America known for strength, low density, and a very porous grain. Frequently used for model rocket fins. [Read More]


A Born Again Rocketeer (BAR) is a person who once pursued rocketry as a hobby and returned t' it at a later time in life. Well, blow me down! A BAR is an individual who has re-discovered t' hobby/sport after an absence o' several years. Blimey! See Also: BOR [Read More]

Barrowman Method

A mathematical technique for calculatin' t' center o' pressure o' a subsonic rocket at low angles o' attack. Named for James S. Barrowman, who developed t' method in 1966. [Read More]

Base Drag

Base drag is a component o' aerodynamic drag caused by a partial vacuum in t' rocket's tail area. Ahoy! T' vacuum be t' hole created by your rocket's passage through t' air. Base drag changes durin' flight. While t' motor is firing, t' drag is minimal since t' tremendous volume o' gas generated ... [Read More]


T' line betwixt t' tracker and t' launcher in t' single tracker method for findin' altitude, or t' line betwixt t' t' trackin' stations in t' two tracker method. Begad! [Read More]


North American hardwood known for very tight even grain and fairly good ease o' working. [Read More]


Ballistic and Test Evaluation System; T' propellant grain geometry used in most high power reloadable motors; t' grain has a central core, matey, t' length o' each grain is ~1.5 time its diameter and t' ends are uninhibited; t' grains burn from t' ends as well as t' core, makin' each grain shorter ... [Read More]


Bureau o' Alcohol Tobacco and Firearms; a federal regulatory agency. What t' BATFE be formerly called. Arrr! Sometimes called ATF. Arrr! [Read More]


Bureau o' Alcohol Tobacco Firearms and Explosives; a federal regulatory agency. Avast, me proud beauty! Sometimes called ATF, BATF (older acronyms). [Read More]


Part o' a model set aside for a specific purpose such as t' payload or electronics bay. Ya scallywag! [Read More]


Barrowman Center o' Pressure; see Barrowman Method [Read More]

Beam , shiver me timbers, Structural

A rigid body designed t' transmit loads in shear or bendin' transversely t' its point o' support. A fin is actually a structural beam. Aye aye! [Read More]


A device that produces an auditory signal, shiver me timbers, assistin' searchers t' find a rocket after it has landed. [Read More]

Bernoulli Effect

A phenomenon first described by t' 18th century Swiss scientist Daniel Bernoulli who studied t' pressures in movin' fluid streams. T' effect states that movin' air will have a lower pressure than t' still air around it. Arrr! This be t' principle behind how airplane wings generate lift and why ... [Read More]

Bernoulli Lock

A phenomenon similar t' t' Krushnic Effect where t' rocket seems t' be "glued" t' t' pad at liftoff. This afflicts larger, flat-bottomed rockets launched too close t' pads with flat blast deflectors. Begad! T' exhaust gasses escape at great speed through t' small annular space betwixt t' ... [Read More]

Bernoulli Principle

A physics principle that states t' pressure exerted by air perpendicular t' its direction o' travel decreases with an increase in velocity. Well, blow me down! This be t' theoretical principle upon which airplane wings work. An airplane wing's airfoil is unsymmetrical, its upper surface havin' a greater curve than ... [Read More]

Binder (propellant)

A material which binds t' contituent elements o' a composite propellant into a solid (usually rubbery); provides t' fuel for t' composite propellant; see HTPB and PBAN [Read More]


North American hardwood known for its pliancy and tight grain. Blimey! [Read More]

Black Brant (II, III, ya bilge rat, IV, V, ya bilge rat, X)

A commonly-modeled Canadian soundin' rocket. [Read More]

Black Powder

Black powder be t' original explosive said t' have been invented in China. A mixture o' carbon, (charcoal), sulfur and potassium nitrate (saltpeter). [Read More]

Black Rock

A famous (at least t' us rocketeers) dry lakebed in Nevada, which is home t' t' BALLS launches (and many others) [Read More]


A trademarked name for thin-walled body tubin' made from phenolic impregnated paper and used with model rockets built for competition, especially superrocs. It was prized by some competition rocket flyers because it was stronger than ordinary cardboard tubing, but lighter than fiberglass. ... [Read More]

Blade Twist

T' pitch angle variation on a helicopter blade from root t' tip. Ahoy! [Read More]


Long thin wing, rotated around a central hub, such as on a propeller. Begad! Blimey! [Read More]

Blast Deflector

A plate or other device that protects flammable materials like grass; surroundin' a launch pad, from bein' ignited by rocket exhaust. Aye aye! [Read More]

Blister (Paint)

Air bubble formed under a skin o' paint. Usually caused by heat applied t' that spot or improper/incomplete preparation before paint. [Read More]


A buildin' used for t' preparation and launchin' o' a commercial or military rocket, usually heavily reinforced. Nay needed in hobby rocketry. Avast! [Read More]


Blow-by be t' hot motor gasses escapin' past t' delay grain and ignitin' a motor ejection charge prematurely. Avast, me proud beauty! [Read More]


T' physical ejection o' propellant through t' front o' t' rocket body. Begad! See CATO [Read More]

Boat Tail

A taperin' section which reduces a rocket's tail diameter and improves aerodynamic efficiency through t' reduction o' base drag. Blimey! [Read More]

Body Tube

A cylindrical tube that makes up t' body o' t' rocket. Ya scallywag! Typically made o' cardboard, fiberglass or carbon fiber. Arrr! See Airframe [Read More]

Bonus Delay

Slang for an unexpectedly long delay, sometimes resultin' in airframe damage or parachute stripping. See Zipperin' [Read More]

Boost Glider

A winged aircraft which is powered into flight by a rocket motor, then returns t' t' ground as a glider after ejectin' its motor or motor assembly. See Rocket Glider. Blimey! [Read More]

Boost Phase

That part o' a rocket's flight in which t' propellant is generatin' thrust. Blimey! Also known as Thrust Phase [Read More]


In a multi-stage rocket, me hearties, t' first stage. In a parallel staged rocket, t' pods containin' t' motors with t' shortest burn time. In a complex single-stage rocket, me hearties, t' term sometimes refers t' t' part that contains t' motor assembly. [Read More]


A "Burned Out Rocketeer" (BOR) be t' counterpoint t' a "Born Again Rocketeer" (BAR). A BOR is someone who has been goin' at t' hobby too intensely such as in preparation for a major contest. Also, "Big Obnoxious Rocket" [Read More]

Boundary Layer

T' very thin layer o' fluid close t' t' surface o' a solid in an airflow. Begad! [Read More]

Bowlin' Ball Loft

A a contest in which t' goal is t' launch a bowlin' ball t' t' highest altitude; a common contest at LDRS. [Read More]


See Black Powder [Read More]


British SpaceModelin' Association [Read More]


Body Tube [Read More]

Bucket Recovery

See Re-Kitted [Read More]


A bend or kink formed by overstressin' t' airframe. Avast, me proud beauty! [Read More]


Repeated forces experienced by a model due t' disturbed unsteady airflow. Avast! [Read More]


A hollow component, such as a fin, made up o' a number o' structural parts. Begad! [Read More]


A solid partition in t' rocket, especially one set perpendicular t' t' rocket's long axis, designed t' nay allow gases t' pass. Ahoy! [Read More]


Round, me bucko, woven elastic material, often used as shock cord in high power rockets. Avast! Blimey! [Read More]

Burn Rate Catalyst

An additive used t' increase t' burn rate o' a propellant (iron oxide is a typical catalyst) [Read More]

Burn Rate Modifier

An additive used t' increase or reduce t' burn rate o' a propellant [Read More]

Burn Rate Suppressant

An additive used t' slow t' burn rate o' a propellant (oxamide is an example) [Read More]

Burn Rate

T' rate at which a substance is consumed by burning, such as propellant or a fuse. Well, blow me down! [Read More]

Burn String

Helicopter blade deployment method usin' thin strin' t' hold blades t' t' body o' t' rocket. Avast, me proud beauty! Ejection gases and particles burn through t' string, allowin' for blade deployment. [Read More]

Burn Time

T' time that it takes for a motor t' fully expend its fuel. [Read More]


T' chemical reaction that occurs within a rocket motor producin' a high velocity gas. Blimey! Blimey! See also Neutral Burn, Progressive Burn, Regressive Burn [Read More]

Burned Out Rocketeer

A "Burned Out Rocketeer" (BOR) be t' counterpoint t' a "Born Again Rocketeer" (BAR). Blimey! A BOR is someone who has been goin' at t' hobby too intensely such as in preparation for a major contest. Begad! [Read More]

Burnout Velocity

T' velocity achieved by t' model at burnout. [Read More]


T' point at which propellant is exhausted in a motor. [Read More]

Burst Disk

A thin disk whose purpose is t' isolate propellants (or components o' t' propellant) until t' motor is ready for operation [Read More]

Butt Joint

A joint made by gluin' an edge t' a surface, such as a fin t' a body tube. [Read More]

- C -


A fuel grain geometry where t' grain has a radial slot cut on its edge; t' burn is relatively neutral until t' end; an Aerotech G64 reload is a C-slot [Read More]


A super fine silica. Aye aye! Unlike microballoons, which are tiny glass spheres, Cabosil is "cut' glass fibers and very light. Used as a filler in epoxy fin fillets t' reduce weight, and control saggin' and drippin' in thin epoxies. Avast, me proud beauty! [Read More]


Cyano Acrylate: a thin, very strong adhesive also known as Super Glue. Comes is gel, fast, medium, slow, black, (thicknesses/speedset) for different applications. Well, blow me down! Blimey! [Read More]


Computer Aided Design [Read More]


Caliber is used in rocketry as a comparison t' t' rocket's diameter. Arrr! Caliber is usually used when referin' t' some function o' length, e.g. Blimey! "T' CP should be behind t' CG by at least one caliber." "One caliber" means a distance equal t' t' diameter o' t' rocket. Often, t' word Caliper will ... [Read More]


A caliper is a device used t' measure t' distance betwixt two opposin' sides o' an object. Ya scallywag! T' word caliper is often mistakenly used in place o' t' word Caliber . It is an easy mistake t' make since a caliper is a tool that may be used t' measure t' diameter o' a rocket and t' diameter defines ... [Read More]


T' increase in curvature o' an airfoil along its chord. Arrr! [Read More]

Cambered Airfoil

An airfoil (wing) on which only t' top surface is tapered, me bucko, t' bottom surface remainin' flat. Well, blow me down! [Read More]


A paint scheme used t' conceal an object in its background. [Read More]


A fin or win' located at t' middle or front o' a rocket. Blimey! Canard fins are often used on guided missiles since they make t' missile less stable and easier t' steer. Because canard fins move t' center o' pressure forward and tend t' destabilize model or high power rockets, they are only used for ... [Read More]

Candy Motor

See Sugar Motor [Read More]


T' fabric o' t' top o' a parachute. [Read More]

Canted Nozzle

A nozzle positioned so that its line o' thrust is nay parallel t' t' direction o' flight. See Vectored Thrust [Read More]

Cantilever Beam

A projectin' member, fixed at one end rigidly and free at t' other. Wings and fins are both cantilever beams. [Read More]

Capacitive Discharge

A type o' launch controller which uses a large capacitor t' store electrical energy from a battery. When commanded by t' launch controller, t' capacitor discharges a large current into t' igniter. Begad! Blimey! These controllers are often used with large cluster rockets t' ensure that all o' t' motors ... [Read More]


Canadian Association o' Rocketry reflectin' changes in t' CARS regardin' rocket associations. Begad! [Read More]

Cardboard Cutout Method

An old method o' determinin' t' Center o' Pressure (CP); this is typically t' most conservative estimate o' CP ; this be t' CP at an angle o' attack o' 90 degrees - t' worst possible situation [Read More]


Canadian Armament Research and Development Establishment. Now known as DREV - Defence Research Establishment Valcartier. [Read More]


Canadian Aviation Regulations . Aye aye! Regulations affectin' hobby rocketry are in Sections 101.01 (definitions) and start at 602.42 [Read More]

Case Rupture

T' splittin' o' t' motor due t' excessive pressure in t' combustion chamber. [Read More]

Case, Casing

T' outside framework o' a rocket motor. Ahoy! [Read More]

Cast Propellant

A solid propellant formed by t' pourin' o' a soft propellant into a mold t' solidify into a hard grain. See Grain. Ahoy! [Read More]

Castin' Tube

A tube in which propellant is cast, typically cardboard [Read More]


A contrived initialism for "Catastrophe At Take Off," t' abbreviation CATO is used as a noun and is generally defined as "a catastrophic failure." Although originally used t' describe t' dramatic malfunction o' a rocket motor, me bucko, t' use o' CATO has broadened t' include a range o' calamitous events ... [Read More]


Short for "catastrophe", cato is used as a noun and is generally defined as "a catastrophic failure." Although originally used t' describe t' dramatic malfunction o' a rocket motor, me hearties, t' use o' cato has broadened t' include a range o' calamitous events such as a rocket "shredding" in flight due t' ... [Read More]


Contest Director; also Compact Disk if nay shootin' rockets [Read More]

Center o' Gravity

T' point at which a rocket balances when completely prepped for flight. [Read More]

Center o' Pressure

T' point at which t' aerodynamic lift on a rocket is centered. See also:'s Center o' Pressure Library . Arrr! [Read More]

Centerin' Ring

A rin' o' paper, cardboard, plywood, or other material which connects t' motor tube t' t' airframe, ensurin' that t' motor remains parallel t' t' rocket's main axis. A motor tube requires at least two centerin' rings. More powerful motors sometimes require more. Ya scallywag! [Read More]


Code o' Federal Regulations [Read More]


See Center o' Gravity. [Read More]


Slang term meanin' "Cheap and Dirty." Most common usage referes t' "CHAD-staging" in which a booster motor is attached t' t' aft o' a rocket motor t' convert a single-stage rocket into a two-stage rocket. [Read More]


A list o' items t' be performed; this is highly recommended on complex projects; everyone has heard o' them, but many rockets have been lost because it sounded like too basic a procedure. LPR Checklists and HPR Checklists . Arrr! Blimey! [Read More]


A class o' chemical which is extremely dangerous when used as a rocket propellant [Read More]


T' short dimension (front-to-rear) o' a glider's wing. Blimey! See Span. Begad! [Read More]


Slang for a condition in which a motor fails t' produce maximum thrust. Ahoy! T' rocket's speed and altitude suffer as a result. In a serious case, t' rocket does nay achieve adequate air speed and crashes. [Read More]


Intermittent burnin' o' a rocket motor, accompanied by t' sound o' a steam engine starting. [Read More]


International Aeromodellin' Commission o' FAI, which includes among other hobby disciplines, arrr, Spacemodellin' (model rocketry) [Read More]


Center o' Lateral Area; t' balance point determined by t' Cardboard Cutout Method o' determinin' CP. Ya scallywag! See Cardboard Cutout Method. Avast! [Read More]

Class B Motors

Rocket motors containin' more than 62.5 grams o' propellant or motors that impart more than 120 newton-seconds o' thrust. Arrr! [Read More]

Class C Motors

Rocket motors contain less than 62.5 grams o' propellant or impart 120 newton-seconds o' thrust or less. Well, blow me down! [Read More]


A rocket design that is streamlined and free o' projections. [Read More]

Clip Whip

Short extensions at t' end o' a launch system with microclips. Blimey! [Read More]


A rocket that is built t' exactly replicate another produced rocket, it is often an Out o' Production (OOP) rocket [Read More]

Closed Breech

Piston launcher where t' piston is mounted on t' launcher, t' motor is mounted in t' model and t' piston movement is upwards with t' model. [Read More]


T' front and aft sections o' a reusable motor assembly, which connect t' t' motor casin' by threads, snap rings, or other method. [Read More]


Canadian Launch Safety Office, a division o' Transport Canada that governs safety and issues all launch waivers for rocketry in Canada, me bucko, rangin' from approval o' t' Canadian Model Rocket Safety Code t' permittin' satellite launches at t' Spaceport, shiver me timbers, Fort Churchill, Manitoba [Read More]


See clusterin' [Read More]


A boost technique which uses 2 or more motors side by side in t' same rocket. Begad! Safe operation o' rockets with different motor thrusts, in a cluster would be t' ensure symetrical thrust around t' center vertical axis o' t' rocket. Avast! This is also sometimes accomplished by cantin' motors toward t' ... [Read More]

Coastin' Phase

That part o' t' rocket's flight betwixt burnout and t' airstart o' t' next stage or betwixt burnout and activation o' t' recovery system. Avast! [Read More]

Coefficient o' Drag (Cd)

A dimensionless number used in aerodynamics t' describe t' drag o' a shape. This number is independent o' t' size o' t' object and is usually determined in a wind tunnel. It is part o' t' basic drag equation F=.5*rho*V^2*Cd*A where F be t' drag force, arrr, rho be t' air density, me bucko, V be t' air ... [Read More]

Cold Power

A type o' rocket motor powered by CFC refrigerant under pressure. Well, blow me down! Blimey! All support for this line be discontinued in t' mid-seventies because o' concern over t' effect o' CFC's on stratospheric ozone. Ya scallywag! Blimey! [Read More]

Combustion Chamber

T' part o' t' motor where t' actual combustion occurs. Composite fuels require a set pressure in t' combustion chamber t' continue burnin' at t' proper rate. Blimey! Failure t' maintain t' pressure results in chuffing. [Read More]

Competition Model

Model whose design is optimized expressly for a particular competitive event. Begad! Blimey! [Read More]


A manufactured part required t' assemble a model, shiver me timbers, such as fins. [Read More]

Composite (material)

Two or more separate and distinct materials, t' combination o' which produces a new material with more desirable properties such as increased strength, lower density or better workability. Arrr! [Read More]


A solid rocket motor type which uses two or more substances for combustion, matey, neither component bein' black powder. Begad! A typical composite motor in hobby rocketry uses rubber as a fuel and ammonium perchlorate as an oxidizer. Ahoy! [Read More]

Compound Dihedral Angle

A "bent wing", in which a glider's win' describes two straight planes at different vertical angles, with t' tip pitched at a steeper angle than t' root. Begad! See Dihedral [Read More]


Havin' a common center. Well, blow me down! [Read More]

Cone Stability

T' inherent stability o' conic shapes t' fly without fins provided t' CG is ahead o' t' CP. [Read More]


See Nose Cone [Read More]


T' arrangement o' fins, wings and other parts o' a rocket or aircraft. Avast! [Read More]


O' or pertainin' t' a cone. [Read More]


An unstable flight condition in which a rocket's spin causes t' aft portion o' t' rocket t' describe a circle. Arrr! Conin' greatly increases aerodynamic drag and reduces peak altitude. Stability is often described in units o' "Caliber" and a long, me bucko, thin rocket with small fins may have several ... [Read More]

Contact Cement

An adhesive that is applied t' both parts t' be joined and allowed t' set up. They are bonded on contact, usually permanently. [Read More]

Contest Acronyms

T' NARRRRR uses a bewilderin' number o' acronyms t' describe its contests. Arrr! As with most things o' this nature, me hearties, thar be a logic t' t' namin' which makes things much easier t' understand once learned. Blimey! T' basic structure o' an event name is a prefix, t' event acronym and a suffix. Ahoy! T' prefix is ... [Read More]


T' condition o' a continuous circuit in a launch system once safety has been closed. A continuous electrical circuit will allow electricity t' flow, so in t' context o' a launch controller "Continuity" means t' igniter circuit is correctly connected and t' rocket motor is ready t' be ignited. [Read More]

Control Surfaces

Surfaces such as flaps and elevons used t' control t' attitude o' a rocket or glider aerodynamically. Begad! [Read More]


T' trademark name for an igniter produced by AeroTech, Inc. Arrr! It is a laminated assembly consistin' o' a two copper foil strips separated by an insulator, with a quantity o' pyrogenic compound on one end. Avast, me proud beauty! It normally requires a special clip for electrical connections, but some rocketeers have ... [Read More]

Core Ejection

Ejection o' a central pod holdin' t' motor from t' aft o' t' model. [Read More]

Core Sample

What happens when an airframe devoid o' nosecone punches into t' ground without benefit o' recovery system. Begad! Named for t' tubular sample o' sod and dirt stuffed into t' body tube on impact. Arrr! Also known as "drillin' for oil." See Lawn Dart [Read More]


T' hole or slot in t' grain o' propellant in a motor. Alteration o' t' core's shape determines t' thrust characteristics o' t' motor. Blimey! [Read More]


T' process, usually marked in seconds countin' down t' zero, o' t' final preparation and launch o' a rocket. [Read More]


A section o' tube used t' connect 2 sections o' larger body tubing. Ahoy! [Read More]


Material coverin' t' framework o' a structure. [Read More]


See Center o' Pressure. [Read More]


Close Proximity Recovery: an electronically-controlled system that permits highaltitude rockets t' have most o' their descent controlled with a drogue. Avast, me proud beauty! T' main parachute deploys at lower altitude. [Read More]


Consumer Product Safety Commission. Rules restrict use o' HPR motors (H and up) t' adults 18 years o' age and up. [Read More]

Craze (Crazing)

Crackin' o' paint or foggin' o' acrylic resin due t' incompatibility o' paint, primer, adhesive, shiver me timbers, and/or material. [Read More]

Cross Section

T' area exposed if a part is cut through. Ya scallywag! [Read More]

Cruise Missile

Description o' a rocket which for one reason or another turns downrange and for a short time flies parallel t' t' ground; a stricter definition is a small, me hearties, pilotless, me bucko, rocket powered airplane [Read More]


Adhesive developed through t' space program. Adhesive hardens very smartly and forms a high strength bond without t' mixin' o' components. Begad! Blimey! Also known as Superglue, Crazyglue, and CA. [Read More]

- D -


An unpowered vehicle, with t' same aerodynamic characteristics as a rocket. A dart is one method o' propellin' a payload package t' a maximum altitude. Well, blow me down! T' dart rides on top o' a large booster, possessin' a higher coefficient o' drag. Durin' powered flight t' dart acquires all t' momentum o' ... [Read More]

Data Reduction

T' procedure for transformin' raw instrumentation data into useful parameters [Read More]

Davis Douche

Variant o' t' flash pan, where wicks are inserted into each motor and t' wick ends are put into t' pan o' BP. See Flashpan, with Caution. [Read More]


Dual Deploy [Read More]

Death Dive

See Power Prang [Read More]


T' difference, in degrees, betwixt t' angles o' attack o' t' wings and stabilizer o' a aircraft. Blimey! This difference builds in some inherent stability, ya bilge rat, allowin' t' aircraft t' recover from dives and stalls. Avast! [Read More]


A reduction o' velocity. [Read More]


Bendin' or displacement from t' neutral position due t' loadin' from some outside force. Aye aye! [Read More]


See Blast deflector [Read More]


T' processin' o' a propellant usin' vacuum processing; reduces bubble that may make t' burn less uniform or even cause a CATO [Read More]


An electronic, mechanical, or pyrotechnic device that permits t' rocket's unpowered ascent betwixt motor burnout and t' deployment o' t' recovery device. Begad! Typically, t' delay is a pyrotechnic grain which separates t' propellant from t' deployment charge and which burns at a known rate. Well, blow me down! T' ... [Read More]


A tough resilient plastic (acetal resin) that is used for rail buttons [Read More]

Delta Wing

Win' planform in t' shape o' a large triangle, matey, used for supersonic flight conditions. [Read More]


Change in velocity [Read More]


Ratio amount o' a substance in a set volume. Avast, me proud beauty! [Read More]

Deployment Bag

A bag constructed o' some fireproof material such as Nomex, shiver me timbers, in which a rocket's parachute is packed. Blimey! T' bag serves t' protect t' parachute from hot deployment charge gasses, and assists in t' orderly deployment o' t' parachute t' prevent shroud tangling. [Read More]

Deployment Charge

T' pyrotechnic charge which pressurizes t' part o' t' rocket containin' t' recovery system, me bucko, deployin' t' recovery device. Blimey! [Read More]


T' condition o' releasing, or deploying, a parachute or other recovery device. [Read More]


It was started in 1998 by Dave Lee so that modelers, rocketeers, and most specifically readers o' t' Usenet newsgroup rec.models.rockets could showcase their talents, matey, display their design on t' internet, arrr, and win t' acclaim o' their peers. Prizes were donated by those enterin' t' contest or ... [Read More]


A rocket that uses rods in place o' fins; typically 8 rods extend out o' t' aft centerin' rin' at an angle o' approximately 30 degrees; some history can be found [here] . [Read More]


A device designed t' ruin t' aerodynamic properties o' a aircraft, enablin' it t' safely escape a thermal and return t' t' ground. Arrr! [Read More]


T' be tricked due t' sufferin' a bad case o' launch happiness. [Read More]

Diamond Airfoil

An airfoil on which t' leadin' and trailin' edges are tapered symmetrically t' a point. Arrr! This airfoil is used on missiles designed for supersonic flight. Begad! Sometimes called a Nike airfoil, since t' classic example be t' Nike family o' missiles. [Read More]

Dihedral Angle

T' angle at which a glider's win' tips tilt upward from t' horizontal plane, matey, t' impart roll and yaw control. Avast, me proud beauty! Blimey! [Read More]

Direct Staging

Air start o' a sustainer motor caused by t' burnin' propellant o' t' booster motor. Blimey! [Read More]

Directional Stability

T' ability o' an aircraft t' return t' its original flight direction after bein' forced off course. [Read More]

Display Launcher

A launcher that is nay functional and is used t' show off a model. Begad! Blimey! [Read More]


Motion o' an aircraft in a head down or nose down attitude. Avast! [Read More]


Do It Yourself [Read More]

Dog Barf

Slang for flame retardent cellulose insulation, as used as recovery wadding; see waddin' [Read More]


A liquid lacquer based paint used t' seal t' grain o' wood. [Read More]

Doppler Effect

Change in sound frequency caused by t' source's rapid movement towards or away from t' observer. [Read More]


An uncontrollable competitor's disease, t' symptoms o' which are t' impulsively make last minute changes intended t' improve a tested competition model's performance, only t' have t' modification backfire or cause a disqualification. Avast, me proud beauty! [Read More]


Department o' Transportation: A federal agency responsible for laws concernin' t' roads, especially t' interstate highway system. Transportation o' motors and propellants is often regulated by DOT regulations. Avast! [Read More]

Double Base Propellant

A solid propellant consistin' o' two monopropellants (usually nitroglycerin and nitrocellulose) and various additives. Double base propellants are used as smokeless powders in ammunition. Arrr! They are also used in smaller military rockets but have been largely replaced by composites in larger ... [Read More]

Douche Plate

Metal centerin' plate on t' bottom o' a cluster motor model t' prevent damage caused by t' BP flare-up usin' a flashpan or Davis Douche. [Read More]


T' movement o' a column o' cooler air downwards, opposite t' a thermal. [Read More]


T' practice o' buildin' smaller versions o' larger model rockets. Arrr! See Downscale Rocket Articles . [Read More]


Slang for disqualification [Read More]

Drag Coefficient

See Coefficient o' Drag [Read More]

Drag Form Factor (CdA)

T' Drag Coefficient o' an object multiplied by its cross sectional area. Blimey! This is used t' scale t' drag value for a particular object from t' dimensionless Cd. Theoretically, shiver me timbers, every object o' a similar shape will have t' same Cd regardless o' its size, me hearties, meanin' that both a grain o' rice and a ... [Read More]

Drag Race

An event, usually informal, in which multiple rockets are launched simultaneously. [Read More]

Drag Recovery

Recovery method usin' t' shape o' t' model t' slow t' model down enough for safe recovery. [Read More]

Drag Separation

A phenomenon where t' nose cone is apparently "sucked" out o' t' body right at motor burnout. It is more prevalent on parabola, ogive and other low drag nose shapes. Begad! T' theory (as yet unproven) is that since t' nose cone has much less drag than t' body, its momentum tends t' carry it forward ... [Read More]


Defence Research Establishment Valcartier. Avast, me proud beauty! Formerly known as Canadian Armament Research and Development Establishment. [Read More]

Drillin' For Oil

See Core Sample [Read More]

Drogue Parachute

Small, heavily reinforced parachute designed t' slow t' craft so safe release o' t' larger main chutes are possible. Arrr! [Read More]


Detectable Seismic Event; see Power Prang also know as Death Dive [Read More]

Dual Deployment

See Dual Recovery [Read More]

Dual Recovery

A process by which a rocket is recovered by means o' a streamer or drogue parachute which opens at apogee, followed by a main parachute which opens at lower altitude. See Single-Stage Recovery. Begad! [Read More]


A spray coatin' from Testor's Corp. Ahoy! that protects t' finish o' a model while removin' t' sheen o' t' finish. Blimey! [Read More]

- E -


Slang for electric match [Read More]

Easy Access

A term coined by Aerotech for their HPR motors which have individual grains that are 62.5 grams or lighter (29mm and 38mm). Aye aye! This be durin' t' period when t' BATFE attempted t' regulate rocket motors with more than 62.5 grams o' propellant. For a short period, Aerotech clamed t' have an ... [Read More]


A line o' econonomical composite F and G motors produced me Aerotech; they are sold in pairs and are slightly less expensive than their other motors in a given class, they are also slighly less powerful. Ya scallywag! [Read More]

Egg Lofter

A rocket designed t' carry one or more cackle fruit as payload. Ya scallywag! Used in competition in which t' object is t' boost t' egg t' t' maximum possible altitude and recover it without breaking. Ya scallywag! [Read More]

Ejection Baffle

A physical or mechanical barrier ahead o' a motor mount designed t' absorb t' heat and hot particles o' t' ejection charge while allowin' t' gas t' pressurize t' airframe. [Read More]

Ejection Cannon

A tube or fittin' that holds t' ejection charge and is attached t' t' rocket [Read More]

Ejection Charge

A small charge o' pyrotechnic matter, usually BP, triggered either by t' delay train, timer or an altimeter, used t' deploy t' recovery device. Blimey! [Read More]

Electric Match

1.) A type o' igniter (see igniter). 2.) although sometimes used synonymously with t' term igniter, an electric match usually refers t' an igniter with t' followin' attributes: requires low current t' fire and has a short burn with little flame; these are generally used t' fire ejection charges ... [Read More]


Any o' a number o' electronic devices used in rocket flight, e.g. Altimeters, arrr, Timers, etc. Ya scallywag! [Read More]


An angle on a vertical plane. See Azimuth [Read More]


A moveable surface on t' horizontal stabilizer o' an aircraft. Avast, me proud beauty! T' surface is responsible for pitch control. [Read More]

Elliptical Dihedral

A curved wing, in which t' tip o' a glider's win' curves up at a higher angle than t' rest o' t' wing. Avast! T' angle be t' form o' an arc rather than a sharp turn. Avast! See Dihedral [Read More]


Acronym for Essence's Model Rocketry Reviews, that's here [Read More]

End Burner

A solid motor that does nay have a core and therefore burns only from its end, givin' a neutral burn profile; a shallow core can be used t' provide an initial thrust spike [Read More]

Engine Block

A rin' which is glued into t' motor tube t' contain t' motor durin' thrust, ya bilge rat, preventin' it from movin' forward into t' motor tube while allowin' ejection charge t' pass into t' body o' t' rocket; typically a cardboard rin' or section o' a used motor casing; normally only used in LPR. Ahoy! Blimey! Often ... [Read More]

Engine Hook

See Motor Hook. Avast! [Read More]


An engine is a device that converts potential energy into mechanical work. Our rocket motors are engines because they convert t' chemical energy stored in t' propellant into t' motion o' t' rocket. Arrr! Blimey! Rocket motors based on solid propellants are generally called "motors" rather than "engines" ... [Read More]

Entrance Cone

T' inside portion o' a rocket nozzle, me hearties, which funnels gasses from t' expansion chamber t' t' throat; in most small nozzles is cone chaped [Read More]


A two-part adhesive used extensively in applications requirin' high strength. Chemically, a compound in which an oxygen atom is joined t' two carbon atoms in a chain t' form a bridge. Arrr! Specifically, a resin containin' epoxy groups, that polymerizes spontaneously when mixed with a phenol (see ... [Read More]

Erosion, matey, nozzle

T' wearin' or burnin' away o' t' throat o' t' motor nozzle caused by t' hot gases ejectin' from t' motor. Also called Ablation. Begad! [Read More]


Acronym for Experimental Rocketry [Read More]

Exhaust Clearance

On some models, t' amount o' offset required t' prevent damage t' parts below t' motor nozzle from t' motor exhaust. Avast, me proud beauty! [Read More]

Exhaust Velocity

T' speed o' t' gases ejected from t' motor nozzle. Exhaust velocity is an important consideration in motor design because, accordin' t' Newton's third law o' Motion, t' thrust o' t' motor is at least partially dependent on t' velocity o' t' motor's exhaust. [Read More]

Expansion Cone

T' section o' t' nozzle that increases thrust via t' force exerted by t' expandin' exhaust gasses; may be a simple cone (typical for hobby rocketry) or a more complex shape [Read More]

Experimental Rocketry

A class o' non-professional rocketry beyond HPR. Although some consider this term synonymous with Amateur Rocketry, ya bilge rat, it generally has a somewhat different connotation. Blimey! Experimental Rocketry normally implies t' use o' composite solid fuels (such as AP, AN, shiver me timbers, and sugar motors) and hybrids. Aye aye! Although ... [Read More]

Explosives Act

Canadian law definin' and governin' t' use o' all explosive substances outside t' Canadian Armed Forces. Avast, me proud beauty! [Read More]

- F -


Federal Aviation Administration. Begad! This be t' organization that governs airspace in t' U.S. Begad! HPR hobbyists must obtain a waiver from t' FAA for permission t' fly large or high (2000+') altitude rockets. Blimey! Equivalent t' Transport Canada and t' Air Ministry in t' United Kingdom. [Read More]


Federation Aeronautique International [Read More]


Rigid or semi-rigid coatin' used t' streamline t' airflow around a rocket component stickin' out in t' airflow. Ya scallywag! [Read More]


FAA regulations regardin' airspace use for hobby rocketry. [Read More]


Fin Can [Read More]

Featherweight Recovery

A recovery method used by very light model rockets. Typically, t' rocket ejects its motor and then floats t' t' earth like a feather, its extremely low weight never allowin' it t' become aerodynamically stable. Aye aye! [Read More]


A man-made material consistin' o' glass fibers spun and woven into a mat-like cloth adhered t' a rocket with epoxy resins. It is used t' add strength t' high power rockets, so that they can withstand higher-powered motors than they otherwise could. Although fiberglass is a commonly used word, it ... [Read More]

Fill 'n Finish

Elmer's brand Carpenter's Wood Filler; a common filler for balsa fins, fillets, etc. Avast! [Read More]


A substance applied t' a surface t' fill gouges in t' surface or help shape t' surface. Ya scallywag! See Wood Filler. Ahoy! [Read More]


A smooth line o' adhesive which is built up at t' root o' a fin t' strengthen t' joint formed by t' fin and t' body tube. Aye aye! [Read More]

Fin Alignment Jig

A device used t' align and hold in place fins t' a body tube. [Read More]

Fin Can

1.) A subassembly consistin' o' t' motor tube, me hearties, centerin' rings and fins, 2.) A single component consistin' o' t' fins and a tubular sleeve which fits over a body tube (e.g. t' ACME Fin Canister). [Read More]

Fin Canister

A section o' tubin' with fins mounted on it, intended t' slide over t' airframe. Blimey! Also called a fin can. Begad! [Read More]

Fin Flutter

See Flutter [Read More]

Fin Span

1.) Distance from fin root (where it attaches t' t' body) t' t' fin tip (outter edge); 2.) More commonly used as t' total span from fin tip t' fin tip (might think o' this as t' maximum width o' t' rocket) [Read More]

Fin Wraps

See Paper Lamination [Read More]


A surface at t' aft o' a rocket that serves t' stabilize it in flight. Fins are usually planar surfaces placed at right angles t' t' body tube. Begad! Blimey! [Read More]


T' art o' givin' a model a smooth, shiver me timbers, streamlined outside surface. Well, blow me down! Click here for some great finishin' ideas. Begad! [Read More]


A bulkhead designed t' prevent fire from passin' that point. Avast! [Read More]

Flame Bucket

An openin' at t' base o' a launch pad t' allow t' exhaust t' vent. Begad! One side is angled t' form a blast deflector. [Read More]


a movable control surface on an aircraft or rocket that deflects air. Blimey! Blimey! Ailerons, elevators and rudders are all flaps. Flaps are also used as airbrakes. Blimey! Blimey! [Read More]


A magnesium-filled glass bulb, once commonly used in photography. In rocketry, flashbulbs are used t' ignite thermalite fuses or BP charges for second stage ignition or recovery device deployment. Well, blow me down! They have t' advantage o' requirin' very low electrical impulses t' activate them. However, me bucko, this ... [Read More]


A type o' ignition sometimes used for BP clusters. Blimey! T' rocket is placed in a pan covered with a thin layer o' black powder. When t' rocket is t' be launched, me hearties, t' powder is ignited with an electrical igniter. Aye aye! T' resultin' flash sends burnin' particles into t' motor nozzles and fires all t' ... [Read More]

Flat Spin

A spin around t' short axis o' a rocket while t' craft is descendin' in a horizontal attitude. [Read More]

Flex Wing

A win' that employs a thin flexible for t' main liftin' surface stretched over a semi-rigid frame. Blimey! [Read More]

Flight Card

A card (sometimes a log book entry) that is used t' record t' pertinent details o' a flight at organized launches [Read More]

Flight Line

T' area at a launch site where rockets are prepared by participants. T' forward-most area where spectators are permitted. Begad! [Read More]

Flight Path

T' line connectin' successive positions o' an aircraft while in flight, relative t' t' ground. [Read More]

Flight Profile

A graphic representation o' a aircraft's flight as seen from t' side, showin' its position and altitude. [Read More]


An aircraft or rocket, havin' undergone inspection and possibly testing, ya bilge rat, that has been determined t' be ready and sound t' fly. [Read More]

Floatin' Injector

Refers t' a type o' hybrid motor wherein t' nitrous chamber is integral t' t' motor casing; t' injector is then free t' move within t' casin' based on t' pressure o' t' contained gas; Ratt Works hybrids are examples o' a floatin' injector design [Read More]


An oscillation o' regular period but irregular amplitude caused by a momentary disturbance but maintained by t' characteristics o' t' flutterin' component. Arrr! [Read More]

Flyin' Wing

An aircraft, whose win' is designed and balanced for stable flight, me hearties, that does nay rely on stabilizers or canards t' maintain t' flight stability. Begad! [Read More]


see Fill 'n Finish [Read More]

Foam Board

Paper-backed syrofoam sheets used for displays and posters; may be used for fins and centerin' rings [Read More]

Foam Core

A built up win' usin' shaped Styrofoam rather than t' classic sticks and ribs, then covered with a thin cover o' wood such as balsa. Avast, me proud beauty! [Read More]

Form Drag

Drag resultin' from t' shape o' an object, causin' turbulence o' t' airflow. Begad! An example is a square win' edge versus a rounded streamlined edge. [Read More]

Forward Closure

T' portion o' t' motor which seals t' top end; in single use motors this is glued in; in reloadable motors it is typically an aluminum housin' that either screws into t' case (AT style) or is held in with a snap rin' (Kosdon style); in motors K and below, this closure usually provides for an ... [Read More]

Free Flight

Unconstrained and unassisted flight o' a rocket, relyin' on t' rocket's inherent stability. Aye aye! [Read More]


T' fall o' an object without guidance or retardation other than through drag. Ahoy! [Read More]

Friction Fit

T' joinin' o' two objects, matey, relyin' nay on adhesive but on t' tight fit caused by one object bein' inserted into another, such as t' nose cone inserted into a body tube. Ahoy! [Read More]


T' resistance an object encounters while movin' across t' surface o' another object. Begad! [Read More]

Frontal Area

t' surface area o' a rocket which faces directly into t' airflow. Begad! [Read More]


Family Radio Service; these 2-way radios are commonly used at launches both for voice and occasionally telemetry [Read More]


T' structure or airframe that houses payload, crew or passengers. Begad! Although nay inaccurate, this term is used more commonly with regard t' airplanes than t' rockets. Begad! [Read More]


Fast White Lightning; a fast version o' Aerotech's White Lightnin' propellant [Read More]

- G -


A mechanical device which detects t' presence o' acceleration through t' movement o' a weighted electrical contact. Begad! g-switches are normally used in combination with other electronic devices such as timers. For example, an electronic timer can be programmed t' count down a certain number o' ... [Read More]


A grade o' fiberglass commonly used for fins on high power rockets. G10 designates a laminate made o' fiberglass cloth laid in epoxy resin. [Read More]


A crane and scaffoldin' arrangement, mounted on rails, ya bilge rat, used t' service a fullsized rocket while on t' launch pad. Aye aye! [Read More]

Giant Scale

A Sport Scale event where t' models cannot be smaller than a given minimum size. Contrast Peanut Scale [Read More]

Glandular Conditions

a general, less common, term for upscalin' and downscalin' [Read More]


T' process o' laminatin' rocket components, such as fins and bodytubes, in fiberglass cloth which is soaked in epoxy resin; polyester resin may be used, but is nay recommended. Blimey! See Fiberglass and Pseudo-Glassin' [Read More]

Glide path

T' descent o' a glidin' air vehicle as viewed from t' side. Blimey! [Read More]

Glide Ratio

T' ratio betwixt distance traveled horizontally and t' amount o' vertical drop. [Read More]


T' controlled descent o' an air vehicle usin' control surfaces, ya bilge rat, nay rockets t' maintain control. Ahoy! T' descent is a result o' gravity and liftin' forces generated by t' shape o' t' air vehicle. [Read More]

Glidin' Booster

A booster stage whose fins are placed asymmetrically and is balanced t' achieve a glide after ejectin' from t' rocket. Aye aye! [Read More]

Global Positionin' System

See GPS [Read More]


Gross Lift Off Weight - T' mass o' a rocket completely prepped for flight. Well, blow me down! [Read More]

Glue Rivets

A method o' strengthenin' t' attachment o' balsa fins by pokin' small holes through t' body tube fo allow glue t' seep through and form "rivets" [Read More]


A rocket design series sold by Estes from 1973 -1975. They were described as t' "Zaniest flyin' freaks in t' universe". [Read More]


T' rounded triangular section o' fabric betwixt two longitudinal seams or shrouds in a parachute canopy. Avast, me proud beauty! [Read More]

Gorilla Glue

A popular brand o' polyurethane glue, alternative t' Elmer's ProBond Polyurethane glue. Learn more [Read More]


Gaseous Oxygen [Read More]


Global Positionin' System; a position/location service provided by t' US Government via a constellation o' LEO satellites; good for identifyin' t' exact location o' your launch site; some newer flight computers are providin' a GPS interface. Avast, me proud beauty! [Read More]


In rocketry, any pellet or cast section o' propellant or other combustible material. Avast! T' black powder propellant packed and shaped into a single-use model rocket motor is referred t' generically as a grain. Also, t' direction o' t' fibers in a piece o' wood, such as balsa. See Wood Grain [Read More]


Ground Support Equipment [Read More]


A roughly triangular shaped piece o' material added t' reinforce a joint, often in a corner. [Read More]


A well balanced flywheel, rotatin' at high speed and generatin' a high moment o' rotation. Gyroscopes work t' maintain their original orientation, and so are used t' provide stability t' rockets. Begad! Blimey! [Read More]

- H -


A small robust glider designed t' be launched by hand. [Read More]


High-Speed Anti-Radiation Missile. See ARM. [Read More]


A door in t' side o' a spacecraft or aircraft. Ya scallywag! [Read More]


hazardous materials; term normally used in relation t' shipping/transportation [Read More]


See Helicopter Duration. [Read More]

Head-end Igniter

An igniter that is intalled on t' top o' t' motor; this type o' igniter is currently non-standard in our hobby, shiver me timbers, but is bein' used experimentally for Aerotech 75mm and 98mm motors; this arrangement is nay uncommon on professional rockets [Read More]


An alert called by t' Launch Control Officer if one o' three conditions prevail: (1) A model usin' an advanced technique such as a cluster is about t' be launched. Blimey! (2) An untried rocket design is about t' launch and t' results are uncertain. Avast, me proud beauty! (3) A recovery system has failed, and it is possible ... [Read More]


Wind blowin' generally into t' front o' an aircraft, thereby slowin' its ground speed. [Read More]

Heat Shrink Tape

A heat sensitive tape that shrinks when heat is applied; used in place o' vacuum baggin' for laminatin' tubes [Read More]

Helicopter Duration

A competitive event in NAR-sanctioned launches, usin' rockets with helicopter recovery. [Read More]

Helicopter Recovery

A method o' model rocket recovery in which long blades are deployed at apogee so that t' rocket descends gently through auto-rotation. See Helicopter Rocket Reviews . Avast, me proud beauty! [Read More]

Hershey Bar Wing

A rectangular wing, with no taper on either t' leadin' or trailin' edge. [Read More]

High Velocity Gas

T' high velocity gas generated by rocket motors be t' principal mechanism for generatin' thrust. Begad! These gasses produce thrust due t' conservation o' momentum. See Momentum Thrust. Ahoy! [Read More]


See Hand-Launch-Glider [Read More]

Honeycomb Core

A diamond-pattern woven material which looks and behaves somewhat like t' inside o' corrugated cardboard; used for makin' light composite structures [Read More]

Hot Wire Cutting

A technique for cuttin' styrofoam usin' a wire which is electrically heated. [Read More]


High Power Rocketry. High power rockets are defined as having: a single motor with more than 160 Newton-seconds total impulse or an installed impulse o' 320 Newton-seconds and no more than 40,960 Newton-seconds, me hearties, and an average thrust in excess o' 80 Newtons. Arrr! Blimey! (H through N range); Dependin' on ... [Read More]


Homeland Security Act; this Act made changes t' Title 18 o' t' U.S. Aye aye! Code in sections 841 through 844; t' primary change be t' new requirement makin' a LEUP or LUP required for in-state purchase and use HPR motors (over 62.5 grams o' propellant); such permits were previously required only if t' ... [Read More]


Hydroxyl-terminated polybutadiene; a common binder used in composite fuels. See Binder [Read More]


A type o' reusable rocket motor in which t' fuel and oxidizer are kept separate and in different material states (such as a compressed liquid and a solid) until combustion occurs. Well, blow me down! A typical hybrid motor currently uses nitrous oxide gas as an oxidizer, and cardboard or plastic as fuel. Ya scallywag! See Micro ... [Read More]


An arrangement o' liquid fuel and oxidizer which ignites spontaneously when combined. [Read More]


Term used t' describe a vehicle exceedin' Mach 5. Blimey! [Read More]

- I -


Independent Association o' Rocketry. [Read More]


Intercontinental Ballistic Missile. [Read More]


Inner diameter; t' ID is what is specified in standard tube sizes; i.e. Aye aye! 18mm, 29mm. Contrast OD [Read More]

Igniter Plug

Plug o' paper or plastic forced into t' motor nozzle after insertion o' t' igniter, designed t' keep t' igniter pressed against t' propellant. Aye aye! [Read More]


A length o' high-resistance wire, sometimes coated with a flammable material, which is placed in contact with t' motor propellant prior t' t' rocket's launch. Well, blow me down! When an electrical current is passed through t' igniter by t' launch controller, t' wire's high resistance causes it t' become very ... [Read More]


In My Humble [Honest] Opinion [Read More]

Impulse (Relative)

A measure o' t' efficiency o' a rocket engine. Avast! Similar t' Specific Impulse, arrr, it is defined as t' Total Impulse divided by t' mass o' t' propellants. A little dimensional jugglin' shows that this gives t' same units as velocity (ft/sec or m/sec) hence is sometimes called "Effective Exhaust ... [Read More]

Impulse (Specific)

A measure o' t' efficiency o' a motor/propellant system. It is determined by takin' t' Total Impulse and dividin' by t' weight o' propellants. Ya scallywag! This carries t' potentially confusin' units o' "seconds" (as if it had somethin' t' do with t' burn duration) but is due t' weight and ... [Read More]

Impulse (Total)

A measure o' t' total momentum imparted t' t' rocket by t' motor. Well, blow me down! It is defined (for those who know calculus) as t' integrated area under t' thrust-time curve. For t' rest o' us, it can be thought o' as t' motor's average thrust times t' duration o' t' burn. Measured in N-sec or Lb-sec. Blimey! [Read More]


Thrust force multiplied by time. T' units o' measurement are usually Newtons and Seconds. [Read More]


A device for determinin' a rocket's apogee without t' use o' electronics. Begad! Blimey! A distance is measured off from t' launch pad prior t' launch. At t' time o' launch, me bucko, an observer stands at t' measured point and keeps t' inclinometer aimed at t' rocket. T' inclinometer mechanically records t' angle ... [Read More]

Indian Fire Brigade

derisive term for stompin' out grass that has caught fire. [Read More]

Indirect Staging

Air start o' t' motor on a sustainer stage by some means other than usin' t' forward-shot bit o' propellant from t' booster motor. Ahoy! Blimey! (pictured rockets have their own electronics t' start each stage, arrr, second picture shows an actual separation and t' upper stage has just ignited.) [Read More]

Induced Drag

Drag resultin' from lift generated by t' foils and liftin' body o' a aircraft or rocket. [Read More]

Injector Throat

T' openin' in t' Injector housing. See also Throat [Read More]


In a hybrid motor, t' unit that introduces t' nitrous oxide into t' combustion chamber [Read More]

Instrumentation Amplifier

An device that amplifies t' low level signal from a device such as a load cell into a useful signal; often also conditions/filters t' signal; may be incorporated into a computer interface card [Read More]


A section o' a rocket in betwixt two stages, such as t' interstage spacin' rin' betwixt t' first and second stage o' t' Saturn V. Begad! [Read More]


Symbol for Specific Impulse [Read More]

- J -


A self-inflatin' parachute airfoil developed by Domini C. Jalbert. It is very maneuverable and be t' current standard airfoil in skydivin' parachutes. Begad! Blimey! [Read More]

Japanese Tissue

A thin tissue used by aeromodelers t' cover t' frames o' model aircraft; often used t' cover t' surface o' balsa fins [Read More]


Jet Assited Take Off; despite t' term 'jet', this is basically t' same as RATO; this may be t' more common term [Read More]

Javelin In

See Lawn Dart [Read More]

Jet Deflector

See Blast Deflector [Read More]


Just In Case: Any precaution taken t' avoid trouble, shiver me timbers, such as sandin' residue off igniter clips. Ahoy! [Read More]


A tool that uses dowel, blocks o' wood, me bucko, clamps and/or forms t' allow precise shapin' and/or construction o' hard t' assemble parts, matey, or mass production o' commonly used parts such as centerin' rings. Avast, me proud beauty! [Read More]


T' identifier for Aerotech's Black Jack propellant; "provides t' high visibility trackin' o' dense black exhaust"; t' most difficult Aerotech propellant t' ignite [Read More]

- K -

Kaplow Clip

A popular type o' motor retainer designed by Bob Kaplow. [Read More]


A synthetic fiber, originally woven into mats for use in bullet-resistant body armor. Aye aye! Blimey! Keelhaul®©™ is highly resistant t' tearin' or burning. Well, blow me down! Blimey! Keelhaul®©™ thread is used in some model rockets as a shock cord. In model rockets, this provides t' advantage o' allowin' t' cord t' be anchored t' t' motor mount ... [Read More]


A liquid, usually o' t' Freon family, used t' accelerate t' set time o' cyanoacrylate adhesive. Well, blow me down! [Read More]


1.) T' practice o' modifyin' a rocket kit t' achieve some result other than that intended by t' manufacturer; 2.) Takin' two (or more) kits and combinin' ("bashing") them into a new design. Often used as a contest event (Team Kitbash, where teams compete, Kitbash Duration, Scale Kitbash, shiver me timbers, etc) ... [Read More]

Kitchen Sink

T' launch every flyable rocket in one's inventory at a single event or within t' span o' one day. Usually results in or be t' result o' launch happiness. Avast, me proud beauty! [Read More]


Potassium nitrate (KNO3); t' oxidizer used in 'sugar' motors [Read More]

Kraft Tubing

AKA paper/cardboard tubing, me bucko, a common rocket airframe and motor mount material. Blimey! This material is impregnated t' make things like phenolic and phlexible phenolic tubing. [Read More]

Krushnic Effect

A very dramatic phenomenon where your rocket makes a tremendous amount o' noise and smoke but doesn't go anywhere! This happens when t' motor is recessed into t' body tube by more than one tube diameter. Ya scallywag! If so recessed, t' cylindrical volume below t' motor forms a secondary expansion chamber ... [Read More]

- L -

L1, L2, L3

Levels one through three: reference t' t' three levels o' high power rocketry certification. Arrr! Blimey! Unless you are in Canada, Eh? [Read More]

Lake Stake

A lawn dart or core sample on t' playa. [Read More]

Laminar Flow

A smooth flow o' air, noted for lack o' turbulence. In current theory , it is modeled as consistin' o' layers o' air havin' similar speed and density. [Read More]

Laminated Wood

Wood made from o' multiple layers, commercially made plywood bein' t' most common example. [Read More]

Land Shark

T' condition in which a rocket, shiver me timbers, for whatever reason, fails t' attain air flight and slides along t' ground under power. [Read More]

Landis Loop

A rin' used in a tower launcher t' keep t' back end o' a egglofter centered durin' launch. Invented by Geoff Landis and named for him by Bob Kaplow. [Read More]

Launch Controller

An electrical device used t' activate t' motor igniter, which in turn ignites t' motor. T' launch controller should always incorporate a lock-out device such as a key, shiver me timbers, t' prevent accidentally activatin' t' igniter before t' rocket is ready t' be launched. [Read More]

Launch Happy

Euphoria from bein' overly addicted t' burnt fuel fumes on a particular day. Aye aye! Symptoms include repeatedly launchin' a model on increasingly more powerful motors until thar are no motors left or t' rocket shreds. [Read More]

Launch Lug

Usually, a tube attached t' t' side o' t' rocket t' accommodate a launch rod, t' stabilize t' rocket while buildin' up air speed. [Read More]

Launch Pad

An assembly containin' t' launch rod or tower and blast deflector if any, which permits t' rocket t' remain steady until launched. Aye aye! [Read More]

Launch Rail

A stiff rail, often with a cross section in t' shape o' a square letter C or I. Ya scallywag! Lugs on t' rocket ride on t' rail. Ya scallywag! Usin' a rail rather than a rod provides t' advantage that a rail can be made much stiffer than a rod, providin' better wind resistance and preventin' vibration-induced whippin' o' ... [Read More]

Launch Rod

A stiff rod, whose diameter can be from 1/8" t' 1" dependin' on t' size and weight o' t' rocket, along which a rocket flies for t' first few feet o' its travel. Begad! T' launch rod stabilizes t' rocket's flight while it builds up air speed. [Read More]

Launch Tower

A launch pad containin' any sort o' stabilizin' device other than a launch rod. In model rocketry, a tower commonly consists o' 3 or 4 smooth rods which support t' rocket on all sides, eliminatin' t' need for a launch lug. [Read More]

Laundry, The

Slang term for recovery components, especially t' parachute(s) [Read More]

Lawn Dart

Similar t' a Core Sample but requires t' nosecone t' remain in place prior t' impact. Named after a lawn game o' t' sixties in which large darts were thrown into t' air t' land inside rings placed on t' ground about 25' apart (as in horse shoes). [Read More]


Live Biological Payload. Transport o' any vertebrate animal is currently in violation o' all rocketry safety codes. Blimey! [Read More]


Launch Control Officer. Well, blow me down! Person in charge o' controllin' t' range and launchin' rockets. Avast! [Read More]


Large and Dangerous Rocket Ships: t' name o' t' annual TRA launch. Avast, me proud beauty! [Read More]

Leadin' Edge

T' front edge o' a win' or fin. [Read More]


Low Earth Orbit; an orbit below 1000km [Read More]


1.)BATFE Low Explosive User Permit for rocket motors with greater than 62.5 grams o' propellant, as well as other substances deemed by t' government t' be low explosives such as Thermalite. Begad! Blimey! 2.) a federal permit required t' purchase, use, shiver me timbers, or store HPR motors whenever interstate commerce or ... [Read More]


One o' t' toughest and most versatile engineerin' thermoplastics; often used for clear fins; made by GE Plastics [Read More]


"Local Hobby Shop" [Read More]

Liftin' Body

a wingless aircraft whose body generates t' lift required t' fly [Read More]

Liftoff Mass

See GLOW [Read More]

Linear Aerospike

An approach, pioneered by t' Rocketdyne company (now a division o' Boeing) in t' 1970s, places t' combustion chambers in a line along two sides o' t' nozzle. Well, blow me down! A Linear Aerospike was planned for t' now defunct Lockheed-Martin X-33 project. [Read More]


A model builders plywood, noted for its low density. Begad! [Read More]


Loadable Motor System - a new (2007) type o' motor system by Aerotech. Begad! Essentially a single use motor that is assembled by t' consumer. Ahoy! [Read More]

Load Cell

An electro-mechanical sensor that converts force or weight into an electrical signal; used in motor test stands [Read More]

Longneck Rocket

On EMRR, arrr, a rocket whose length t' width ratio is 30:1 or more [Read More]

Lovelace Effect

See Drag Separation [Read More]

Low Power

Typically rockets flyin' on motors in t' A t' D range. [Read More]


Liquid Oxygen [Read More]


See Low Power [Read More]

Lucerne Soft Landing

A condition - experienced only on ground surfaces o' cracked playa clay - in which a rocket which has landed remains in a semi-upright position with one fin stuck in a crack in t' ground. Begad! [Read More]


See Launch Lug. Ya scallywag! [Read More]


Limited Use Permit; a federal permit which allows limited purchase and use o' HPR motors within your state o' residence; still requires approved storage [Read More]


Launch Vehicle [Read More]

- M -


Used for Mods, OOP, Plans and Scratch. This be added as a section t' t' classic EMRR web site t' differentiate standard product reviews from these other articles. Well, blow me down! [Read More]


Model Aeronautics Association o' Canada . Begad! Equivalent t' t' AMA. Canadian aeromodelingliaison organization t' t' CIAM through t' AERO CLUB OF CANADA. [Read More]

Mach Buster

A rocket design t' break t' speed o' sound. Here are some o' them click here [Read More]

Mach Diamonds

A diamond shaped pattern that develops in t' supersonic flow o' gas from a rocket nozzle; these are caused by shock waves which reflect off o' t' pressure boundary betwixt t' exhaust plume and t' ambient environment. Begad! [Read More]

Mach Number

An expression o' velocity calculated by dividin' t' actual velocity by t' speed o' sound. At sea level this speed is 760 mph. [Read More]


Magnetic Apogee Detector. Avast, me proud beauty! See scratch-build article click here [Read More]


An ATF-approved storage device for large rocket motors and other lowexplosive devices. Begad! [Read More]


A rod or bar used as a core around which a material is molded, cast, me hearties, or wound; typical uses in rocketry are t' form t' core in a propellant grain, matey, t' make an airframe, or mold a nosecone [Read More]

Marginal Stability

Rockets with a static margin betwixt 0.5 and 1.0 caliber are considered t' be 'marginally stable'. These rockets may fly fine, but extra attention must be given t' t' wind conditions, thrust-to-weight ratio, and launch rod velocity. Begad! For example, short stubby rockets with a length-to-diameter ... [Read More]

Mass Ratio

Final mass (after propellant burn) divided by initial mass. [Read More]


T' point durin' t' powered flight phase o' a rocket's ascent at which acceleration stresses on t' airframe are t' greatest. Aye aye! This be t' point at which a shred is most likely t' occur. Arrr! [Read More]

Maximum Thrust

T' peak thrust a motor generates. [Read More]

Maximum Weight

Generally used as t' maximum weight o' a rocket for a specific motor and delay. Avast, me proud beauty! This is based on t' thrust curve and average thrust o' a motor. T' main objective is t' have t' rocket travelin' at a velocity where t' aerodynamic forces produced by t' fins are suffficient t' keep t' rocket ... [Read More]

Mean Chord

A wing's root chord plus its tip chord, divided by two. [Read More]

Medusa Nozzle

A nozzle which has multiple exit ports. [Read More]


Methyl ethyl ketone; a solvent which, per t' manufacturer, arrr, is required t' rejuvinate Igniterman pyrogen once it has fully dried (acetone is also required) [Read More]

Mercury Switch

An electrical switchin' device consistin' o' an oval glass bulb which contains two electrical contacts (penetratin' t' bulb, and at one end o' t' oval) and a drop o' mercury. Aye aye! In hobby rocketry, mercury switches are used t' detect t' absence o' acceleration in a movin' rocket. When t' rocket ... [Read More]


Malfunctionin' Engine Statistical Survey; t' NAR's mechanism for gatherin' motor failure data [Read More]

Micro Balloons

Tiny glass globules which are sometimes added t' epoxy in applications like fin fillets, t' reduce weight. [Read More]

Micro Bubbles

See Micro Ballons [Read More]

Micro Engine

T' series o' 10.5mm engines produced by Apogee Components; production is currently halted [Read More]

Micro Grain

A propellant that consists o' finely ground particles or (normally) zinc/sulfur; these propellants are fast burning, VERY volatile and DANGEROUS [Read More]

Micro Hybrid

A small hybrid motor that uses nitrous oxide cylinders which are used in t' grub service industry; fuel grains are typically paper and t' motor's thrust is in t' 'D' t' low 'E' range. See Hybrid [Read More]


Small, toothless electrical clips commonly used t' connect t' launch system t' t' igniter on model rockets. Ahoy! [Read More]

MicroMaxx Engine

T' series o' 6mm engines produced by Quest Aerospace; t' original MMX (0.2N) has been replaced with MMX-2 (0.31N) [Read More]

Mid Power

Typically rockets flyin' on motors in t' E t' G range. Ya scallywag! [Read More]

Mid-body Ejection

T' practice o' placin' a rocket's separation point midway up t' body tube, helpin' t' prevent tube zippering. [Read More]


Missin' In Flight. A rocket that disappears with no sign o' t' recovery system deployment, and no other obvious failure mode (e.g. Begad! Prang or CATO). Sometimes called "into orbit." [Read More]

Mini Engine

T' series o' 13mm engines produced by Estes; identified in t' engine designation by a trailin' 'T'; example: A10-3T [Read More]

Minimum Diameter

a model whose diameter is just large enough t' accommodate its motor. [Read More]


Multiple Launch Rocket System [Read More]


Motor Mount [Read More]


acronym for Quest MicroMaxx motors. [Read More]

Model Rocket News

T' oldest continuously published rocketry periodical. Begad! Started by Vern Estes and his small crew in 1960, ya bilge rat, it is still sent t' all o' Estes's active mail order customers. Somewhat sophomoric in style, it contains a great deal o' practical information, arrr, especially for beginners. It has survived a ... [Read More]

Model Rocket

An aircraft that ascends into t' air usin' some form o' reaction motor, without t' use o' aerodynamic liftin' surfaces. Model rockets have t' followin' characteristics: Gross launch weight, ya bilge rat, includin' t' motor(s), ya bilge rat, does nay exceed 1500 grams. Arrr! Motor power does nay exceed 160 newton seconds o' ... [Read More]


Slang for Model Rocket. Avast, me proud beauty! Blimey! [Read More]


A combination o' parts or components arranged and mounted or packaged as a single unit. T' parts work together t' perform a specific function or functions. Begad! [Read More]


In mechanics, a) t' tendancy t' cause rotation about a point or axis; b) t' measure o' this tendency; c) t' product o' a force or mass and its perpendicular distance from its axis or fulcrum [Read More]

Momentum Thrust

T' component o' a motor's thrust due t' t' expulsion o' gas [Read More]


Monocopters are single-bladed helicopters. T' engine, me hearties, whether an airplane engine or rocket motor, both drives and counteracts t' lift forces produced by t' single blade. Well, blow me down! See Monocopter Reviews [Read More]


Model aviation coverin' consistin' o' colored heat shrinkable vinyl, applied with a tackin' iron. Often used as trim tape. [Read More]


A grain geometry where t' circular core touched t' outer wall o' t' grain; a moonburner is regressive throughout its burn [Read More]

Motor Adapter

A replacable unit which allows a smaller diameter motor t' fit in a motor tube. [Read More]

Motor Clip

See Motor Hook [Read More]

Motor Code

[Read More]

Motor Diameter

T' diameter o' a hobby rocketry motor casing. Most commercially-manufactured motors are made in standard sizes. Begad! Motor diameters are most commonly expressed in millimeters. T' most commonly seen motor diameters are 10.5mm, 13mm, 18mm, 24mm, ya bilge rat, 29mm, 38mm, ya bilge rat, 54mm, 75mm, me hearties, and 98mm. [Read More]

Motor Hook

1.) A device for retainin' t' motor on a model rocket. 2.) A section o' sprin' metal, t' length o' t' motor and with tabs bent on either end and attached t' t' motor tube; t' back end is left unconstrained so it can be bent away from t' motor casin' durin' insertion and removal; normally ... [Read More]

Motor Mount

T' assembly/part o' t' rocket that t' motor(s) is installed into for flight [Read More]


A motor is a device that creates or imparts motion. Aye aye! Rocket motors based on solid propellants are generally called "motors" rather than "engines" though it is nay incorrect t' call them "rocket engines" as Estes does. T' term "engine" is usually reserved for liquid-propellant rocket engines ... [Read More]


See Mid Power [Read More]


See T' Model Rocket News [Read More]

Murphy's Law

T' guidin' principle o' Rocketry preparation: "If anythin' can go wrong, shiver me timbers, it will." [Read More]

Music Wire

A high grade, stiff wire made t' low tolerances that comes in a wide variety o' diameters. Commonly used t' make springs, it is also known as piano wire. Begad! Blimey! Most often used in model rocketry as launch rods. Aye aye! Blimey! [Read More]


an extraordinarily strong polyester film made by DuPont; commonly used for parachutes [Read More]

- N -


National Aeronautics Association [Read More]


National Advisory Committee for Aeronautics; predecessor t' NASA [Read More]


National Association o' Rocketry Annual Meet: T' annual week-long launch hosted by t' NAR. Blimey! [Read More]


T' annual NARRRRR convention. [Read More]


National Association o' Rocketry, Visit NARRRRR [Read More]


National Association o' Rocketry Trainin' Rocketeers for Experience and Knowledge. Ya scallywag! It consists o' a series o' achievement levels in rocketry, matey, each requirin' more skill t' complete than t' previous one. Avast! [Read More]


National Aeronautics and Space Administration [Read More]

National Association o' Rocketry

T' National Association o' Rocketry (NAR - ) is one o' t' two major organizations representin' rocketry hobbyists in t' United States. [Read More]


Nose Cone [Read More]

Neck Snapper

A motor & Rocket combination that leaves t' pad too fast for t' eye t' follow. Avast! [Read More]

Neutral Burn

When t' thrust o' t' motor is relatively flat throughout t' burn. Blimey! See also Burn, Progressive Burn, ya bilge rat, Regressive Burn [Read More]

Neutral Point

CG location on a glider, which would result in exactly neutral stability (such that if t' glider were disturbed, thar would be no pitchin' moment) [Read More]

Neutral Stability

T' condition in which a rocket's CP and CG are at t' same spot. Dynamically, this creates a situation in which a rocket may fly steadily in dead air but can't recover if t' angle o' attack is greater than zero. Ya scallywag! [Read More]


T' typical unit o' measurement for rocket thrust. Avast! One newtonsecond is one newton o' thrust maintained for one second. [Read More]


T' amount o' force required t' accelerate one kg, one meter per second per second. 4.45 newtons equals one pound o' force. [Read More]

NFPA 1122

Standards code for U.S. Avast, me proud beauty! Model Rocketry. Ya scallywag! [Read More]

NFPA 1127

Standards code for U.S. Avast! High Power Rocketry. Ahoy! [Read More]


National Fire Protection Association - Private corporation for settin' safety standards. Begad! [Read More]


Refers t' t' metal content (nickel/chromium) o' t' igniter wire most commonly used in model rockets. Ya scallywag! Nickel/chromium is chosen as a material because it has high resistance and high strength. When exposed t' an electrical current, it will glow yellow-hot before burnin' through. Arrr! [Read More]

Night launch

A launch conducted after sunset; requires an FAA waiver [Read More]

Nike Airfoil

See Diamond Airfoil [Read More]

Nitrous Oxide

(N2O)Gaseous oxidizer used in current hybrid rocket motors. Avast! See Hybrid and Micro Hybrid [Read More]

No Joy

When a rocket motor fails t' ignite. Useage: no joy on pad 13. [Read More]


A lightweight, fire-resistant Nylon fiber, ya bilge rat, originally woven into fireproof garments for fire fighters, race car drivers and astronauts. Begad! Also commonly used in aircraft upholstery. Avast, me proud beauty! In hobby rocketry, shiver me timbers, Nomex is used as sheaths and bags t' protect elastic shock cords and parachutes. Well, blow me down! See Deployment Bag [Read More]

Non-Survivable Event

see Prang [Read More]

Nose Block

A turned piece o' balsawood used t' connect two sections o' body tube. Just like a stage coupler, but it is a solid block. Ya scallywag! This allows you t' create a "payload section" that be t' same diameter as t' main body tube. Avast, me proud beauty! Essentially a long nosecone shoulder (with no nosecone)used t' connect two ... [Read More]

Nose Blow Recovery

Recovery method for light models by simply ejectin' t' nose cone and havin' it come down attached on t' shock cord. [Read More]

Nose Cone

T' pointed object at t' front o' a rocket. Ya scallywag! Cones are nay always strictly cone-shaped. Avast! They are sometimes rounded but are most commonly ogive (a pointed arch). Nose cones are an important consideration in rocket design, since they provide two ways t' move t' center o' gravity forward if needed; ... [Read More]

Nose Heavy

T' condition in which a glider is trimmed into a dive or a rocket has excessive mass in t' nose. [Read More]

Nose Weight

A weight, often o' lead, epoxy or modelin' clay, which is added t' t' nose o' a rocket t' move its center o' gravity forward and improve t' rocket's stability. Ahoy! [Read More]


abbreviation for nitrous oxide [Read More]


T' part o' t' rocket motor that smoothly expels gas from t' combustion chamber; typically made from phenolic (in SU or AT reloads), shiver me timbers, graphite (Kosdon-style reloads), or clay (Estes motors). Components o' t' nozzle include t' entrance cone, throat, me hearties, and expansion cone [Read More]


National Sport Launch: an annual three-day launch hosted by t' NAR. [Read More]

- O -


A rubber gasket used t' contain gasses in solid rocket motors [Read More]


1) Slang term for a strange-lookin' rocket. Odd-rocs are often made in t' shape o' other, ya bilge rat, non-rocketry-related items. 2) Anythin' clearly nay originally intended t' fly. Blimey! Blimey! Odd shapes, odd conversions. T' antithesis o' 3FNC; 3) Are strange lookin' things that often shouldn't fly. (And ... [Read More]


Outer (or outside) diameter. Contrast ID [Read More]


o-give (oh'jiev, oh jiev') - In rocketry, t' shape o' a common type o' nose or tail cone. If t' sides o' t' cone are curved rather than straight, t' geometric shape o' t' cone is actually an ogive rather than a cone. Arrr! [Read More]

One-Caliber Stability

A widely-accepted rule o' thumb for rocket stability: T' center o' gravity should be approximately one body width (one "caliber") ahead o' t' center o' pressure. [Read More]


Out O' Production. Blimey! This is a reference t' a rocket that was once but is no longer produced by a commercial manufacturer. Reproduction o' plans, arrr, parts lists, arrr, and scalin' information for once-popular out-of-production model rockets has become an Internet cottage industry. [Read More]


An propellant additive which makes t' propellant opaque; a translucent propellant will absorb ultraviolet light from t' flame, which may cause combustion t' start deeper in t' grain, causin' a Cato. [Read More]

Open Breech

A piston launcher in which t' motor travels up t' piston tube and engages t' motor mount. See Piston Launcher [Read More]

Optimum Mass (Weight)

T' mass required t' lift a rocket t' t' highest possible altitude on a given motor. Begad! [Read More]

Orange Book

BATFE explosives rule book. See BATFE [Read More]

Oscillation, Parachute

T' swingin' from side t' side o' a payload under a parachute. Arrr! [Read More]


Direction parallel t' t' lateral axis o' t' rocket and perpendicular t' t' centerline. [Read More]

Over Stability

Rockets with a static margin over two calibers are considered 'over stable'. Blimey! These rockets will tend t' weathercock badly and may oscillate or even become unstable. Care should be given t' t' thrust-to-weight ratio, launch rod velocity, and wind conditions. [Read More]


See Krushnic Effect. Blimey! [Read More]


A substance which provides oxygen t' a combustion process, aidin' in t' speed and efficiency o' combustion. Blimey! T' addition o' an oxidizer t' t' chemical process o' combustion can cause a fuel that would barely burn under normal atmospheric conditions t' burn so enthusiastically that it can be used ... [Read More]

- P -

Pad Manager

Person responsible for assignin' pads and controllin' t' launch pad area. Helps rocket flyers set up pads and rockets for flight. [Read More]


Atmospheric pressure, 14.6 psi [Read More]

Paper Lamination

A techique used t' laminate fins (primarily balsa) t' cover t' grain and add strength; t' practice o' puttin' layer(s) o' paper over balsa fins t' add strength across t' surface and create an additional shock absorption layer. [Read More]

Parachute Duration

A popular competitive event in NAR-sanctioned launches. Arrr! [Read More]


A piece o' plastic, me hearties, cloth, nylon, matey, or other material, shaped somethin' like an umbrella when deployed, which slows t' descent o' a rocket. [Read More]


A parachute-like device which has an airfoil structure; may be steerable. [Read More]


A flexible, kite-like glider deployed like a parachute and designed t' be a recovery device. [Read More]

Parallel Staging

A practice similar t' clustering, in which two or more "stages" mounted parallel t' t' main motor ignite simultaneously. Blimey! T' "stages" usually contain shorter-burning, higher-thrust motors than t' main airframe (or sustainer), and drop off when their motors burn out. [Read More]


A flat piece o' plastic or other material, formed into a circle or polygon, arrr, which is used as a parachute. This be t' most common type o' parachute used with model rockets. [Read More]


Usually, a glider which is boosted into flight by bein' attached t' t' airframe o' a model rocket which is modified t' accept it. [Read More]

Pay Forward

A Harry Stine expression. T' pay back t' mentors o' our youth, nay by tangible means t' t' mentors, me bucko, but by actin' as mentor t' t' next generation. [Read More]

Payload Section

A portion o' rocket airframe set aside for payloads. Also called payload bay. [Read More]


A package or thin' placed in a rocket, which normally does nay contribute directly t' t' success o' t' flight. Aye aye! For example, me bucko, an altimeter used t' record a rocket's maximum altitude is an example o' a payload. Ya scallywag! [Read More]


Polybutadiene Acrylic Acid Acrylonitrile Prepolymer; another binder used in composite propellant. See Binder [Read More]


See Parachute Duration [Read More]

Peanut Scale

A Sport Scale event where t' models cannot be larger than a given maximum size. Contrast Giant Scale [Read More]

Pendulum Rocket Fallacy

T' mistaken belief that a rocket will be stable if t' motor is ABOVE t' rocket's center o' mass, so that t' rocket is "hanging" below t' center o' thrust and will try t' remain upright, me hearties, like a hangin' pendulum. It doesn't work; even Robert Goddard learned that t' hard way. See t' followin' ... [Read More]


T' measure o' diffusion or "leakage" o' gas through a fabric. T' permeability determines t' rate o' descent. Begad! [Read More]

Phase Transition

Changes in t' crystal structure o' a composition resultin' in expansion and contraction; in AN motors, temperature induced phase changes cause crystals t' break away from t' binder and causes erratic burning. See Binder [Read More]


Literally, anythin' containin' phenol, matey, which is a petroleum distillate havin' many industrial applications. Phenolic resin, with which phenolic airframes are impregnated, is made by mixin' phenol with an aldehyde such as formaldehyde, and is used for formin' all sorts o' molded and cast items. ... [Read More]

Phlexible Phenolic

Introduced by Red Arrow Hobbies as an alternative t' t' Phenolic airframe. Ahoy! It is offered as bein' chip and crack resistant from hard landings, etc. Well, blow me down! (even in cold weather) and as strong or stronger laterally than standard phenolic tubes. [Read More]

Piano Wire

See Music Wire [Read More]

Pilot Chute

A small parachute attached t' t' apex o' a large main parachute, me bucko, and so oriented that it emerges from t' airframe first. Air drag from t' inflatin' pilot chute assists t' main chute t' exit t' airframe, pullin' it out apex-first so that it is less likely t' tangle. Ahoy! [Read More]

Pink Book

T' common name for t' NARRRRR Contest Rules Manual. Well, blow me down! See NARRRRR and Contest Acronyms [Read More]


A condition in which a rocket spins on its horizontal axis. Usually caused by a split in a motor casing. Avast, me proud beauty! This condition is highly dangerous, as t' rocket's trajectory is completely unpredictable. [Read More]

Piston Ejection

Ejection o' t' recovery device through t' use o' a solid slidin' bulkhead inside t' airframe. T' use o' a piston eliminates t' need for wadding. Ahoy! [Read More]

Piston Launcher

A type o' launcher used with small competition model rockets. Arrr! At t' moment o' motor ignition, arrr, a piston assists t' motor in launchin' t' rocket. [Read More]


A back-and-forth motion o' t' nose o' a rocket in flight, on t' axis determined as "up-and-down". See Yaw. Arrr! [Read More]


A tool t' shave thin slices o' material in order t' shape or smooth t' material. [Read More]


T' geometric shape o' a win' or fin. [Read More]

Plastic Model Cement

A mixture o' solvent and styrene plastic used t' adhere plastic t' plastic or plastic t' paper. Avast! [Read More]

Plastic Model Conversion

A refittin' o' a static plastic model kit t' allow it t' fly as a model rocket. See Plastic Model Conversion Articles . Avast! [Read More]


An additive which makes a composite propellant softer and more flexible [Read More]

Playa (or pan)

(pronounced /ˈplaɪə/) is a dry or ephemeral lakebed, generally extendin' t' t' shore, or a remnant of, an endorheic lake. Avast! Home t' many big launches in t' Western US. Arrr! Black Rock Desert, home o' TRA's BALLS launch, be t' quintessential example o' a rocketry playa. Aye aye! [Read More]

Plugged Motor

A motor made with a solid bulkhead in t' front end, matey, blockin' any passage o' ejection gases into t' airframe. Avast! [Read More]


See Plastic Model Conversion [Read More]


A win' broken up into multiple panels, arrr, angled in relation t' each other. Begad! [Read More]


A solid plastic made from polymerised styrene [Read More]

Polyurethane Glue

a strong versatile waterproof glue; expands while curin' and tends t' be messy; t' most common rocket use is for inside surfaces such as centerin' rings [Read More]

Pond Dart

Same as Lawn Dart but in t' Pond [Read More]

Pop Pod

T' motor mount on a conventional boost glider. When t' motor deployment charge fires, arrr, t' pop pod separates from t' glider, deploys a streamer and returns t' earth, me bucko, leavin' t' glider free t' glide. [Read More]


A launch lug affixed t' model in such a way that it comes off t' model as it clears t' launch rod or rail. Pop 'n Go Ignition: A technique whereby a powdered chemical accelerant is poured over an igniter placed in t' nozzle t' insure ignition. Aye aye! Typical accelerants include Black Powder, ... [Read More]

Potassium Nitrate

An oxidizer used in black powder and 'sugar' motors; see Sugar Motor [Read More]

Power Prang

(See Prang) Slang term for a condition in which an unstable rocket reverses course and moves toward t' ground while still under power. Also called a Death Dive. Begad! [Read More]


Slang for any condition in which a rocket contacts t' ground without benefit o' recovery system. Well, blow me down! T' origin o' t' term is in dispute. Stine claims (Handbook o' Model Rocketry, 6th ed., p. 196) that it is a British term, originally used in t' aircraft industry t' describe deformation o' an ... [Read More]


T' head o' a TRA Prefecture, me hearties, or t' designated person, t' maintain a line or communications with, me hearties, or t' see compliance to, t' TRA. [Read More]


A club or group affiliated with t' TRA. [Read More]

Pressure Relief Hole

A hole in t' airframe o' an HPR model t' relieve t' difference in pressure betwixt t' inside o' t' model and t' atmosphere, so as nay t' prematurely eject t' nose section. [Read More]

Pressure Thrust

T' component o' a motor's thrust due t' t' difference in t' chamber and ambient pressures [Read More]


A special mix o' paint, me hearties, applied directly as a first coat, that is formulated t' have excellent adhesion and a uniform colour over various materials such as body filler. Aye aye! [Read More]


Pyro Release Mechanism; a mechanical actuator used t' depoy a parachute; activated by an electronic match and a small black powder or Pyrodex (or equivalent) [Read More]


A 38mm reloadable solid propellant motor system produced by Cesaroni Technology Incorporated (CTI). Begad! [Read More]


A 54mm reloadable solid propellant motor system produced by Cesaroni Technology Incorporated (CTI). Avast, me proud beauty! [Read More]

Progressive Burn

When t' thrust o' t' motor increases throughout t' burn. Ya scallywag! See also Burn, Neutral Burn, shiver me timbers, Regressive Burn [Read More]

Propellant Mass Fraction

T' propellant mass divided by initial mass. [Read More]


1. Blimey! a propellin' or bein' propelled, 2. somethin' that propels, me hearties, a drivin' force (Webster) [Read More]

Propulsive Chaff

(Brit.) T' remains o' a shredded rocket while still airborne. Avast! [Read More]


Pacific Rocket Society - An amateur rocketry organization. Begad! [Read More]


Phase Stabilized Ammonium Nitrate; AN that contains a small amount o' nickle salt that eliminates t' phase transitions typically associated with AN motors; sold by CP Technologies [Read More]


T' process o' laminatin' body tubes in polyester hose soaked in MinWax(tm) PolyCrylic(tm); this adds some strength and resiliency, but is nay as sturdy as standard fiberglass laminations. See Fiberglass [Read More]


A model designed and decorated t' appear t' be a scale model. [Read More]


Tetrafluoroethylene; See Teflon(tm) [Read More]

Pumpkin Seed Effect

See: Watermelon Seed Effect [Read More]


Polyvinyl Chloride; a common plastic usually associated with plumbin' pipe; rocket uses have included body tubes, me hearties, ejection cannons, motor casings, me hearties, and even as a propellant binder [Read More]


A black powder substitute made by Hodgton; intended for muzzle loadin' firearms, ya bilge rat, it is actually considered a propellant and does nay require a LEUP for purchase or storage; if contained properly, t' 'P' version shows promise for ejection charges [Read More]


1.)Liquid solution that is used t' make igniters. Aye aye! 2.)A highly flaamable substance used t' ignite rocket motors; typically a liquid that igniters are dipped in; one common commercial pyrogen is Magnalite by Rocketflite [Read More]


O' or pertainin' t' fire or explosion. T' term is most commonly used with reference t' fireworks. Avast! [Read More]

- Q -

Quantum Tube

An aiframe introduced by Public Missiles: These tubes are made in t' USA from a special blended polymer that is extremely durable and easy t' use. Avast! Blimey! Most epoxies and paints will readily adhere t' this material. Begad! Blimey! It has been tested and found compatible with t' followin' paints: lacquer, me bucko, enamel, me bucko, ... [Read More]


See Pseudo-Glassin' [Read More]

Quick Link

A metal loop with a captive nut, which is used t' connect chains, or in our case recovery system components; also known as a threaded connector; typically oval, but may be square, me bucko, pear, shiver me timbers, or delta-shaped [Read More]

Quik Tube

A brand o' tubular concrete forms which are often used for large inexpensive airframes [Read More]

- R -

R.M.R. Avast, me proud beauty! Descon

an on-line rocket design contest started by Dave Lee; Descon Website [Read More]


T' public domain rec.models.rockets newsgroup See for yourself click here [Read More]

Rack Rocket

A multi-staged rocket design where t' motors are held in a rack that also supports a single set o' fins; as successive engines ignite, they eject t' previous used motor; t' rack may consist o' 3 or 4 rods, or slotted tubin' [Read More]

Rail Button

A piece o' plastic or metal that mates with a Launch Rail; forms a 'H' shape when viewed from t' side. Ahoy! [Read More]


See Launch Rail [Read More]

Range Box

A box used t' carry everythin' that you need for flyin' rockets. Controller, arrr, motors, me bucko, ignitors, wadding, pliers, maskin' tape, screw drivers, hobby knife, me bucko, CA glue, parachutes, etc. [Read More]


T' part o' a launch site where t' pads are located. Blimey! [Read More]


T' launch site; or, me bucko, t' distance from an observer t' a tracked object [Read More]


Rocket Altitude Simulation Program; a public domain program that simulates t' flight o' a rocket in one dimension [Read More]


Rocket Assisted Take-Off. Arrr! RATO refers t' a rocket booster that is attached t' a conventional aircraft t' reduce t' distance required for take-off. [Read More]


radio controlled rocket glider [Read More]


radio controlled [Read More]


A (painfully) humorous term that refers t' any situation where a rocket goes t' pieces such as a prang or a CATO. Thought t' have originated at LDRS XIII. Typical usage: "That E-15 sure re-kitted me Black Brant!" [Read More]

Rear Closure

In AeroTech-style cases, shiver me timbers, an aluminum housin' that screws into t' case t' seal t' motor and retain t' nozzle; nay required per-se for single-use or Kosdon-style reloadble motors. See also Forward Closure. [Read More]

Rear Ejection

T' ejection o' recovery device through t' aft o' a model. Arrr! [Read More]

Recovery Harness

Everythin' that is used t' connect rocket components which separate at ejection; may or may nay include a shock cord per-se; term is usually used in HPR where t' cords are made from tubular nylon or Keelhaul®©™(tm) and do nay stretch appreciably. Blimey! [Read More]

Recovery Wadding

See: Waddin' [Read More]

Red Baron

T' condition in which a boost glider's motor pod and recovery system gets tangled with t' glider portion, causin' t' glider t' spiral down as if it had been "shot down". Avast, me proud beauty! [Read More]


A propellant by Aerotech that produces a bright scarlet red flame with white exhaust smoke. Only available in H-M sizes at t' present time. [Read More]

Reefed Parachute

A parachute whose shroud lines are restricted t' prevent full openin' o' t' canopy. [Read More]

Regressive Burn

When t' thrust o' t' motor diminished throughout t' burn. Begad! See also Burn, Neutral Burn, Progressive Burn [Read More]


A launch controller that controls electrical current t' t' igniter through an electrical relay. This arrangement allows t' power source t' be placed close t' t' rangehead, reducin' t' voltage drop through long wires. [Read More]


an organic compound consistin' o' a non-crystalline or viscous liquid substance; see Epoxy [Read More]


A device for keepin' t' rocket motor from bein' ejected by t' force o' t' deployment charge. Avast! [Read More]

Reynolds Number (Rn)

1.) A nondimensional co-efficient that measures t' compression o' air due t' scaling. Begad! This allows scale models t' be tested in wind tunnels; 2.) A dimensionless number used by fluid flow engineers t' characterize t' way a fluid (gas or liquid) will behave when passin' over a solid surface. Ahoy! T' ... [Read More]


See Rocket Glider [Read More]

Rigid Wing

A glider with wings usin' rigid airfoils rather than a parafoil or flexible wing. Begad! [Read More]

Rin' Fin

A fin which is comprised o' a rin' o' tubing, typically larger than t' rockets airframe and usually supported by standard fins. Blimey! [Read More]

Rip-Stop Nylon

a common parachute material; it is distinguished by a fine pattern o' boxes (barely noticeable) that are designed t' keep fabric from tearin' [Read More]


See R.M.R. Blimey! [Read More]


Reloadable Motor System (has also been called Reusable Motor System). A solid rocket motor which can be re-fueled and reused. [Read More]

Rocket Caviar

Mixture o' lead shot and epoxy used for addin' nose weight [Read More]

Rocket Eatin' Tree

Any tree within t' launch field; see Murphy's Law. [Read More]

Rocket Eatumupuses

See Rocket Eatin' Tree. [Read More]

Rocket Glider

A type o' boost glider that has t' characteristics o' a model rocket when ascending, then changes its configuration t' have t' characteristics o' a glider when descending. All parts remain with t' model other than t' spent fuel. Avast! [Read More]

Rocket Mail

Mail that is flown in a rocket t' commemorate its launch; may then be sent t' recipients via snail mail Rockets were apparently used as early as 1902 t' deliver mail from ship t' shore in t' Fiji islands. No known covers survive. On February 2, 1931 Friedrich Schmiedl successfully launched a ... [Read More]

Rocket Rotisserie

A home made device used t' slowly rotate a rocket or component durin' painting, matey, glassing, or sanding. [Read More]


A computer program that allows you t' design any size rocket, and then simulate its flight t' see how high, and how fast it will fly. Begad! Even before you start buildin' your creation, you'll find out if it is stable and safe t' launch. Arrr! Just image how much loot you'll save by doin' all your test ... [Read More]

Rod Whip

T' flexin' o' a rod durin' lift-off, which may cause t' rocket t' head off at an undesireable angle [Read More]

Rogallo Wing

A flexible delta win' platform developed by Francis Rogallo that is popular for kites, matey, hang-gliders and ultralights. [Read More]


A passive, mechanical roll damper mounted a rocket's fins. Consists o' independently actin' wing-tip aelerons with enclosed airstream-impelled gyros wheels. Well, blow me down! [Read More]


Rotational motion o' a rocket through t' long (flight) axis. [Read More]


Acronym for Rocketry Online , one o' t' most comprehensive rocketry sites [Read More]

Root Chord

T' chord at t' root o' a win' or fin. Begad! See Chord. [Read More]

Root Edge

T' edge o' a fin or win' that is glued t' t' airframe. [Read More]

Rotor Blades

Wing-like extensions, rotatin' around a central hub o' a helicopter or autogyro. [Read More]

Rotor Disc

T' disc o' space formed by t' rotation o' rotor blades. Avast, me proud beauty! [Read More]

Rotor Hub

T' central attachment point for t' blades o' a rotor. T' attachment usually determines t' pitch angle o' t' blades. Begad! T' hub can be o' 2 types: fixed or rotating. Well, blow me down! [Read More]


A multi-bladed propeller used t' produce lift or control t' orientation o' an aircraft. Avast! [Read More]


Acronym for t' book "Rockets o' t' World", me bucko, by Pete Alway [Read More]


Reaction Research Society - T' oldest continuously-runnin' amateur rocketry group in t' United States. [Read More]


Range Safety Officer. Aye aye! Person(s) responsible for field safety. Ahoy! Determines suitability o' rockets t' fly at a particular site. Inspects rockets prior t' flight. [Read More]


Ready t' Fly. A rocket which is sold pre-built, as opposed t' a kit. [Read More]

- S -


Standards and Testing; name o' t' NAR's committee that tests and certifies motors [Read More]


A spacer which is used t' align a rocket in a tube launcher; may also seal t' breach; is discarded after launch. [Read More]


Surface-to-Air Missile [Read More]


T' practice o' buildin' model rockets which are replicas o' existin' rockets or other aircraft, which models are constructed t' a size that is a particular percentage o' t' original aircraft's size. Begad! Scale models are often built for competition, and their level o' detail can be very exact. Begad! See ... [Read More]

Scissors Wing

A variable geometry win' planform used on rocket gliders, where t' win' unit rotates and aligns with t' fuselage when nay in glide mode. [Read More]


Safety Check Officer (Deputy RSO) [Read More]

Scott Towel Special

A cheap rocket costin' less than $1, made o' a tube taken from paper towels, toilet paper or gift wrap, matey, a hand rolled paper nose cone, and card fins or tube fins or other recycled material. T' use o' balsa for fins or any other conventional model parts immediately disqualifies t' model as a ... [Read More]


A a rocket that is built from individual parts, as opposed t' bein' bought as a kit. Many times these are original designs. [Read More]


A really, ya bilge rat, obnoxiously loud beeper. Well, blow me down! [Read More]

Screw Eye

A headless screw on which t' shaft is extended and formed into a circular eye. Aye aye! Blimey! [Read More]


t' cancel a launch attempt due t' problems, technical or otherwise. [Read More]


See Shock Cord [Read More]


See Streamer Duration. Blimey! [Read More]


Paint-like substance t' cover wood parts. Sealer seals t' wood grain, preventin' any penetration o' moisture, arrr, allowin' a smoother finish, and t' use o' less paint. Ahoy! [Read More]


A series o' nose cones designed and used for maximum aerodynamic efficiency on very high-speed rockets. T' most commonly encountered cone in this series is a Von Karmon cone. Begad! Blimey! [Read More]

Self Packing

See Re-Kitted [Read More]


A small mechanical device, arrr, which upon receivin' a signal from a radio or timer will perform an action such as t' movement o' a pushrod. [Read More]

Shear Pin

A pin(s) that retain a nosecone t' avoid drag separation; they are sheared off by t' force o' t' ejection charge; often nylon screws are used. [Read More]

Shock Cord Mount

T' attachment point for a shock cord. [Read More]

Shock Cord

A length o' elastic or bungee which provides shock absorption for t' rocket components at t' point o' flight where t' deployment charge fires and t' parachute opens. Begad! [Read More]

Shotgun Recovery

A method o' gettin' your rocket out o' rocket eatin' trees using, well, a shotgun; recommended only as a last resort [Read More]


A slight sharp indentation at t' base o' a nose cone or top or base o' a transition, allowin' t' part t' be slid into a tube while allowin' alignment o' t' rocket sections t' be maintained. Avast, me proud beauty! [Read More]


UK Term: A town in t' UK through which rockets pass through durin' a shred. Well, blow me down! [Read More]


T' condition in which a rocket's airframe fails durin' launch. This is caused when t' force applied by a rocket motor exceeds t' tensile strength o' t' rocket airframe. Avast, me proud beauty! T' effect o' a shred is similar t' an explosion. [Read More]

Shroud (Transition)

A piece o' material, ya bilge rat, often card stock, used t' smoothly allow t' airframe t' go from one diameter t' another. [Read More]

Shroud Line (Parachute)

Lines or strings which pull down on t' edges o' a parachute. T' shrouds come together at their bottom ends t' provide a point o' attachment betwixt t' parachute and t' rocket. Ya scallywag! [Read More]

Single-Stage Recovery

A process by which a rocket is recovered by means o' a single parachute, streamer, me hearties, or group o' parachutes which deploy at one time. See Two-Stage Recovery [Read More]

Sink Rate

T' rate o' vertical drop durin' t' recovery phase o' a flight, matey, in feet or metres per second. Arrr! Sink rate used t' specify parachute or streamer size for a rocket. [Read More]

Skid Mark

A motor by Animal Works that produces a lot o' flame, arrr, black smoke and sparks. [Read More]


T' thin outside surface o' a hollow part or object. [Read More]


Slang term for t' smoke trail left by an unstable rocket which does nay fly straight. Well, blow me down! [Read More]

Smoke Point

T' maximum height in millimeters o' a smokeless flame o' fuel bein' burned in a laboratory apparatus. Begad! This test method provides an indication o' t' relative smoke producin' [Read More]

Snap Ring

A sprin' metal rin' that is intended t' snap into a groove either inside or outside a pipe or shaft; inner snap rings are used t' retain nozzles and forward closures in Kosdon-style reloadable motors, and an outer rin' is usually used as a thrust ring; requires a special set o' pliers t' ... [Read More]

Snap Swivel

A small device, arrr, originally developed t' connect fishin' lures t' leaders.,which is attached t' a model rocket's parachute shrouds. Aye aye! This permits t' parachute t' be easily removed and replaced on t' rocket, me hearties, and permits t' parachute t' rotate in relation t' its connection point, which reduces ... [Read More]


Slimy NARRRRR Insider. Begad! A person who associates with (either professionally or casually) members o' t' NARRRRR board o' trustees, thus bein' privy t' t' "inner workings" o' t' organization. Aye aye! Said t' have originated durin' "flame wars" on t' CompuServe Sport Rocketry SIG. Blimey! [Read More]


Slimy NARRRRR Politician. Ya scallywag! Coined by NARRRRR President Mark "Bunny" Bundick, it refers t' an SNI who actually manages t' get elected t' t' NARRRRR board. Aye aye! [Read More]

Snuffer Tube

A small metal tube used t' extinguish a wick such as in a dethermalizer. Avast, me proud beauty! [Read More]

Solar Igniter

Estes Industries brand o' Igniter. Blimey! Made from two wire conductors with a piece o' Nichrome wire connectin' them at one end. T' nichrome wire tip o' t' igniter is dipped in a pyrogenic compound which flares t' ignite t' rocket motor. Ya scallywag! [Read More]

Solids Loading

T' proportion o' solids in a propellant formulation; increasin' t' solids loadin' has several effects, includin' increasin' t' Isp [Read More]

Sonic Barrier

T' zone o' high air density caused by t' compression wave o' an object travelin' near t' speed o' sound. Avast, me proud beauty! [Read More]

Sonic Boom

1.) Sonic boom is an impulsive noise similar t' thunder. It is caused by an object movin' faster than sound, about 750 miles per hour at sea level. An aircraft travelin' through t' atmosphere continuously produces air-pressure waves similar t' t' water waves caused by a ship's bow. Arrr! When t' ... [Read More]

Sonic Speed

T' speed o' sound at t' current conditions o' air density. Aye aye! humidity and temperature. [Read More]

Sono Tube

A brand o' tubular concrete forms which are often used for large inexpensive airframes [Read More]


An artificial sweetener, very similar in appearance and with similar physical characteristics t' both sucrose and dextrose sugars; see Sugar Motor [Read More]

Soundin' Rocket

A professional rocket used t' perform atmospheric experiments. Soundin' rockets take their name from t' nautical term "to sound," which means t' take measurements [Read More]


SpaceCAD makes it easy for you t' design rockets. Ya scallywag! You can view them in 2D and 3D, you can zoom into your design and you can get see how your rocket will look like - before you even start buildin' it. Avast, me proud beauty! Just think o' t' hours saved by tweakin' your design t' t' max without sacrificin' valuable ... [Read More]


UK Term: A town in t' UK where crashed rockets are said t' end up. Avast! Blimey! As in "It wasn't a great flight, matey, she bought a first class ticket t' Spackington via Shredbury and Zipperfield. [Read More]


1.) (Brit.) Slang for t' sound o' a model rocket hittin' t' ground from high altitude. See Prang 2.) Slang term for a crash. Derived from t' sound o' balsa and cardboard hittin' t' ground. 3.) Event followin' catastrophic failure o' recovery device [Read More]


T' long (side-to-side) dimension o' a wing. Avast, me proud beauty! See Chord. Avast! [Read More]


A long, thin, arrr, structural member o' a airframe. Avast! Also, SPAR [Read More]


Special Projects And Research, formerly a department o' DeHaviland Canada (now Bombardier), maker o' satellites and t' original robotic arm for use by t' shuttle in space. Now an aircraft maintenance company, t' robotics and space devisions were sold t' MacDonald-Dettwiller. [Read More]

Specific Impulse (Isp)

T' total impulse o' a motor divided by unit weight o' propellant. [Read More]

Speed O' Balsa

That speed at which a rocket's balsa fins shred. T' speed varies with thickness o' balsa, thrust gradient, type o' glue used and mostly quality o' buildin' technique. Avast, me proud beauty! [Read More]

Spill Hole

A hole in t' center o' t' canopy o' a hemispherical parachute, designed t' reduce payload oscillations caused by t' canopy spillin' air unevenly from its edges. [Read More]

Spin Stabilization

T' use o' spin along t' long axis o' a rocket t' stabilize t' flight, thus makin' t' rocket act as a gyroscope. [Read More]


Tabs attached t' fins and set at an angle, ya bilge rat, intended t' spin t' rocket in order t' stabilize it. [Read More]


T' small (or larger) grooves in paper tubes that spiral up-down t' length. They are induced by t' tube wrappin' manufacturin' process [Read More]

Spool Rocket

A rocket variation made from wire, cable, rope, etc. spools. Arrr! [Read More]

Sport Model

A model rocket designed and built with no specific purpose in mind other than t' fly it. [Read More]

Sport Rocketry

Rocketry activities pursued as a pastime, matey, diversion, or personal enjoyment. Term is often used as a contrast t' "competition rocketry." [Read More]

Spot Landing

A competition event in which t' goal is t' land t' model closest t' a predetermined spot on t' launch field. [Read More]


Abbreviation for Sport Rocketry magazine [Read More]


A small charge o' black powder or other propellant, shiver me timbers, contained in a hollow tube and set off with an electrical igniter. Ya scallywag! T' term is usually used in connection with an electronically-actuated deployment charge for a rocket's recovery system. [Read More]


Space Research Facilities Branch. Ahoy! National Research Council o' Canada. Operator o' t' Black Brants in t' 1960s and '70s [Read More]


Single Stage T' Orbit. Begad! [Read More]


T' tendency o' a rocket t' move in a straight line in t' direction it is pointed at launch. Ya scallywag! Blimey! A hobby rocket employs "passive" stability, in that it depends on its inherent stability (the relationship o' its centers o' pressure and gravity) and t' counterbalancin' pressure o' t' airflow on its ... [Read More]


Stabilizer: Usually refers t' t' fin-like structures at t' aft o' a conventional boost glider. [Read More]


See Booster and Sustainer. [Read More]


T' angle o' maximum lift for an airfoil. Stalls are dangerous because lift dramatically decreases (often t' near zero) at any angle past t' stall point Static Balance - A state in which a model's center o' gravity can be demonstrated t' be in a proper relationship t' t' center o' pressure by ... [Read More]

Stand-Off Scale

A scale model where t' degree o' accuracy should be judged from a distance (i.e. Aye aye! nay too accurately) [Read More]

Static Firing

T' firin' o' a motor, mounted in such a way that t' motor can nay move. Ya scallywag! Used usually with instrumentation, t' permit performance measurement. Well, blow me down! [Read More]

Static Inertia

In mechanics, ya bilge rat, inertia be t' resistance t' change in velocity. Arrr! Static Inertia be t' resistance o' a motionless object t' begin t' move. Ahoy! [Read More]

Stine's Law

T' guidin' principle o' Rocketry construction and flight: "If at first you don't succeed, try followin' instructions." [Read More]

Strand Burner

An apparatus that provides for burn rate measurements o' a solid rocket propellant in an environment o' elevated pressure; sometimes referred t' as t' Crawford Strand Burner [Read More]

Streamer Duration

(SD) A contest event whose purpose is t' maximize t' flight duration o' models with streamers; a common competitive event in NAR-sanctioned launches. Begad! [Read More]


A device for slowin' t' descent o' a rocket, arrr, sometimes used in place o' a parachute in smaller rockets. Well, blow me down! T' streamer consists o' one or more long, narrow lengths o' plastic, fabric or paper which are connected t' t' rocket in t' same fashion as a parachute, arrr, and which deploy and flutter t' slow ... [Read More]

Strin' Test

See Swin' Test [Read More]


A condition in which a rocket's fins, or a glider's wings, are pulled off t' airframe by excess thrust. [Read More]


T' "act" o' havin' wings or fins stripped off an airframe. Ya scallywag! Blimey! Also, me bucko, a pop-pod glider that separates from t' booster pod prematurely. Ya scallywag! Blimey! [Read More]

Stubby Rocket

On EMRR, a rocket whose length t' width ratio is 10:1 or less [Read More]

Stuffer Tube

A small-diameter tube - commonly an extension o' t' motor tube - which is used in large-diameter rocket airframes t' duct deployment charge gases t' t' recovery system storage area. This reduces t' internal area which must be pressurized by t' deployment charge. [Read More]


A very light material made o' expanded polystyrene plastic. Though Styrofoam has little structural strength, is easily shaped into shapes, such as large nose cones and glider wings, arrr, that can be skin-reinforced by fiberglassin' or lamination o' thin wood veneers. [Read More]


Speeds where no local supersonic flow occurs (such as around tip o' nose or leadin' edge o' fin), typically up t' Mach 0.8 t' 0.9, matey, dependin' on t' shapin' o' t' vehicle [Read More]

Suction Lock

T' Mother o' all Base Drag. Begad! See Bernoulli Lock [Read More]

Sugar Motor

An experimental motor that uses a mixture o' potassium nitrate and sugar (typ. sucrose, shiver me timbers, dextrose or sorbitol) as a propellant; also called 'candy motor' [Read More]

Sun Seeker

A rocket with a crude form o' guidance that directs it toward t' sun [Read More]


Usually, a lengthened version o' an existin' model rocket design, used in altitude and duration competition. Avast! Scorin' is based on altitude multiplied by airframe length. Super-Roc has different length limits for different motor classes. Avast! For example; A has a range o' 75 t' 150 cm, C has a range o' ... [Read More]


A speed greater than Mach 1 (760 mph at sea level) and less than Mach 5. [Read More]


An additive which improves a composite propellant's mixin' by coatin' t' AP particles [Read More]


In a multi-stage rocket, t' last or top stage. Avast, me proud beauty! In a parallel staged rocket, t' longest-burnin' motor. [Read More]


Single Use; a disposable motor which cannot be re-used. [Read More]


T' amount o' angle that t' leadin' edge o' a win' has been shifted back from a line perpendicular t' t' airframe o' a model. Ahoy! [Read More]

Swin' Test

A stability test in which a strin' is attached t' a model rocket at t' center o' gravity and then swung around t' head. If t' model is stable, it will head nose into t' direction o' travel. Blimey! This test has a large margin o' error, thus producin' models often overly stable. Arrr! It can nay be used for ... [Read More]


A swivel is a connection that allows t' connected object, me hearties, such as a parachute or streamer t' rotate horizontally and/or vertically. [Read More]

Symmetrical Airfoil

An airfoil (wing) in which both t' top and bottom surfaces are tapered. [Read More]

- T -


T' time interval betwixt ignition and maximum thrust. Blimey! [Read More]


A nut that attaches t' a wooden surface; consists o' an internally threaded shaft and a flat plate with prongs; commonly used t' provide an attachment point for motor retainer clips; see Kaplow Clip [Read More]

Tail Boom

T' spar extendin' past t' wings o' a aircraft t' which t' tail or stabilizer surfaces are attached. Avast! It is usually cut down t' a minimum diameter as required for strength. Aye aye! [Read More]

Tail Drag

See Base Drag [Read More]

Tail Heavy

General description o' a model that will require nose weight t' achieve t' desired CP/CG relationship for stable flight. [Read More]


See Boat-Tail [Read More]


A uniform decrease in diameter in a cylindrical o' near cylindrical part. [Read More]


Team America Rocketry Challenge; an aerospace design and engineerin' event for teams o' US secondary school students, sposored by t' NARRRRR [Read More]


T' polymer PTFE, an extremely slippery material that is inert t' almost every known chemical; rocket uses include lubricants, ya bilge rat, release films, and reusable recovery wadding; patented by DuPont [Read More]


T' transmission o' data t' a remote receiver, usually through t' use o' radio frequency broadcast. Avast! Blimey! [Read More]


T' outline o' a part, made o' a tough material used as a stencil t' produce multiple parts o' that size and shape. [Read More]

Terminal Velocity

1.) T' highest allowed velocity for a shape or design, arrr, any further attempt t' accelerate t' object will result in drag forces completely eliminatin' t' acceleration. 2.) in our sport, ya bilge rat, t' speed o' a Prang or Core Sample [Read More]


A three sided pyramid [Read More]


A device for determinin' altitude by measurin' both elevation and azimuth angles. Blimey! More accurate than a simple inclinometer, which measures only t' elevation angle. [Read More]


A low-explosive device in t' shape o' narrow string, similar t' detonation cord. Thermalite is often used t' enhance t' efficiency o' igniters in large-diameter composite motors, and is sometimes used for airstartin' motors. Avast, me proud beauty! T' possession and use o' Thermalite now requires a LEUP t' be issued ... [Read More]


An upward movin' column o' air caused by surface heatin' o' t' ground; a good thin' in duration events [Read More]


A plastic which is solid when cold, but which may flow and be re-formed multiple times with t' application o' heat. Avast! [Read More]

Three-fold Attachment

See: Tri-Fold Attachment [Read More]

Three-Fold Method

T' Three-Fold Method be t' method Estes (and others) use t' attach shock cords t' t' inside o' an airframe. T' Three-Fold Method consists o' a tapered strip o' paper that is folded over on itself with glue and t' shock cord. Blimey! See also: Tri-Fold Mount [Read More]


1.) T' narrowest cross-section o' a rocket motor's nozzle. Well, blow me down! 2.) T' actual openin' in a rockets nozzle; t' throat diameter along with t' exit cone area play a large role in t' motor's performance [Read More]

Through T' Tube (TTT)

See Through T' Wall [Read More]

Through T' Wall (TTW)

An HPR fin attachment technique which provides much greater strength than t' typical surface mount used in model rocketry. T' use TTW, slots are cut in t' body tube where t' fins mount and t' fins are built with extended tabs on t' root edge which fit through these slots. In one form o' TTW, me hearties, ... [Read More]

Thrust Augmentation

A method used in jet engines t' increase thrust by injecting/ventin' air into t' exhaust jet; no examples o' thrust augmentation in rocket engines are available. [Read More]

Thrust Curve

1.) T' propulsive force o' a rocket motor plotted against time. Ya scallywag! See Thrust 2.) ThrustCurve.Org is a website that contains motor specifics include size, weight, average thrust, total thrust, and thrust curves. Aye aye! See also EMRR's Tools [Read More]

Thrust Decay

T' gradual loss o' thrust at t' end o' a motor's burn. Avast, me proud beauty! [Read More]

Thrust Plate

A plate, me hearties, usually metal, whose purpose is t' distribute t' force o' a motor on t' end o' t' motor tube [Read More]

Thrust Ring

1.) See Engine Block 2.) In some cases, t' thrust rin' is part o' t' motor. It may be part o' t' aft closure, matey, or a flanged permanently mounted on a single-use motor. Begad! T' purpose is t' prevent t' motor from pushin' up into t' motor mount while t' rocket is under thrust. In absence o' an ... [Read More]

Thrust Stand

An instrumented test stand used t' measure motor performance [Read More]


T' propulsive force developed by a rocket motor durin' t' rocket's powered ascent. Ahoy! T' force produced by a rocket motor is described by Newton's second law o' motion "Force equals mass times acceleration" and by Newton's third law o' motion "for every actin' force, thar be an equal reactin' ... [Read More]


An electronic device which is used t' control events durin' a rocket's flight, such as sustainer motor ignition or recovery system deployment. A timer is normally combined with another device such as an accelerometer or g-switch, ya bilge rat, which provides a start signal for t' timer. Begad! [Read More]

Tip Chord

T' chord at t' tip o' a win' or fin. See Chord. [Read More]


An alteration o' a rocket's flight direction caused by interaction o' t' launcher, rocket, and wind direction as t' rocket leaves t' launcher. [Read More]

Tomy Timer

A mechanical timer which is used t' deploy parachutes in water rocket competitions [Read More]

Total Impulse

T' total thrust produced by a rocket motor across its full burn time. Begad! Usually expressed in Newton-seconds. Ahoy! [Read More]

Trailin' Edge

T' aft edge o' a win' or fin. Arrr! Blimey! [Read More]


Part o' an airframe that smooths t' airflow from one airframe component t' another o' different diameter. Also called an Adapter. [Read More]


T' condition o' crossin' t' sonic barrier, me hearties, from t' initial appearance o' local shock waves (typically around Mach 0.8 t' 0.9), extendin' t' speeds where all local airflow becomes supersonic (typically Mach 1.05 t' 1.2). Ahoy! This be t' period o' maximum aerodynamic stress in a supersonic flight. [Read More]


Tripoli Rocketry Association, Visit TRA [Read More]


T' Rocketry Forum; an online, graphical discussion forum. Visit TRF [Read More]

Tri-Fold Attachment

A tri-fold attachment or "Three-Fold Method," be t' method Estes (and others) use t' attach shock cords t' t' inside o' an airframe. T' Three-Fold Method consists o' a tapered strip o' paper that is folded over on itself with glue and t' shock cord. See also: Tri-Fold Mount [Read More]

Tri-Fold Mount

A tri-fold mount is a shock cord attachment created usin' t' Three-Fold Method. [Read More]

Trim Monokote

A brand o' self-adhesive vinyl trim; unlike regular Monokote, ya bilge rat, this does nay require heat for adhesion [Read More]


T' act o' adjustin' surfaces on an aircraft through warpin' or shiftin' trim tab angles t' achieve stable controllable flight. Arrr! [Read More]

Tripoli Rocketry Association

T' Tripoli Rocketry Association (TRA - ) represents rocketry hobbyists in t' US and around t' world. [Read More]


Truely Recyclable Motors; Kosdon's reloadable motor system [Read More]

Troll (Internet)

A person who enjoys unrest, starts arguements, me bucko, and tries t' upset people on media such as R.M.R. and chat forums [Read More]


Two Stage T' Orbit. [Read More]


Identifier for Aerotech Blue Thunder propellant; "produces a bright violet-blue flame with a minimum o' exhaust smoke"; t' easiest Aerotech's propellant t' ignite [Read More]


T' T' Motor Mount: An extension o' TTW fin mounting, me hearties, in which t' fin tab which has passed through t' airframe wall contacts t' motor mount tube and is bonded thar with epoxy. [Read More]


"Tip-to-Tip" - t' application o' Carbon Fiber or Fiberglass over an entire fin's surface t' strengthen t' fin. [Read More]


See Through T' Wall [Read More]

Tube Fin Rocket

A rocket that uses several tubes rather than conventional fins for stability. Tube Fin Rocket - A rocket that uses several tubes rather than conventional fins for stability. Blimey! [Read More]

Tube Fins

T' case where t' fins are made o' sections o' tubin' that are tangentially connected t' t' airframe; 6 sections o' tubing, t' same diameter as t' airframe, matey, will completely enclose an airframe. See also EMRR's Tools . Aye aye! [Read More]

Tumble Recovery

A recovery method where a very light model rocket ejects its motor and shifts its CG behind t' CP, thus preventin' stable flight and causin' t' model t' tumble end over end. [Read More]


Slang for wind tunnel. Blimey! Also, a long hollow conduit on t' side o' a rocket used t' protect wirin' travelin' from t' top t' t' bottom o' t' rocket. [Read More]


A device used on rockets with conical cross-sections, such as egg lofters, t' prevent t' extra drag which occurs when t' laminar airflow separates from t' airframe. Begad! This is done by causin' t' airflow t' become turbulent at t' point where it would normally separate from t' airframe. [Read More]

Two Part Foam

expandin' foam that reacts when t' two components are mixed; t' reaction is chemical in nature and does nay require moisture as do t' canned aerosol foams. [Read More]

Two-Stage Recovery

See Dual Recovery [Read More]

- U -


Strictly stands for Unidentified Flyin' Object, but is used for any saucer-like design (e.g. Estes Snitch , Art Applewhite's Saucers ). [Read More]


United Kingdom Rocketry Association [Read More]


T' practice o' buildin' very large HPR versions o' smaller model rockets, several times t' size o' t' original. [Read More]

Umbilical Mast

A mast extendin' beside a rocket while sittin' on its launcher, designed t' support wirin' or hoses t' t' rocket. Avast! It is often designed t' pull t' wirin' or hose out o' t' way once t' model's motors ignite. [Read More]

Under Stability

See Marginal Stability [Read More]

Unibody Staged

See Rack Rocket [Read More]

Unsymmetrical Thrust

A condition in which t' thrust o' a motor or motor cluster is nay parallel t' t' axis o' t' rocket. This is most often caused by t' failure o' part o' a cluster o' motors t' ignite or a protuberance extendin' into t' exhaust stream o' a single motor. [Read More]


T' practice o' buildin' large versions o' smaller model rockets. See Upscale Rocket Articles . Begad! [Read More]

- V -


A method o' makin' lightweight plastic components like nose cones by usin' heated plastic, a mold, and a vacuum pump that is attached t' t' mold. Ya scallywag! [Read More]

Vacuum Bagging

A technique used in laminatin' rocket components in fiberglass or other material; after t' material is applied and wetted with resin, t' component is placed in a sealed plastic bag and t' air is sucked out. Arrr! Blimey! T' bag places uniform pressure over t' part while t' resin sets, resultin' in a very ... [Read More]


Visual Center o' Pressure; a public domain program t' graphically determine t' CP [Read More]

Vectored Thrust

A condition in which a rocket motor's thrust is nay parallel t' t' motor's axis. Aye aye! This is achieved by cantin' t' motor's exhaust nozzle, and is often done t' reduce t' unsymmetrical thrust that results from outboard motors failin' t' ignite on clustered-motor rockets. [Read More]

Vent Hole

A hole in a Body Tube t' allow ejection pressure t' vent into another tube or into t' atmosphere. [Read More]

Von Karmon

A nose cone shape. Von Karmon is a special case o' t' Sears-Haack series o' nose cone shapes, used on very high-speed rockets. Arrr! It be t' most efficient volume per unit nose drag. Blimey! [Read More]

- W -


Waddin' or Recovery Waddin' is a non-flammable filler material placed in a model rocket airframe before t' parachute is inserted. Recovery waddin' acts as piston t' help ensure deployment o' t' recovery system and it protects t' parachute and other deployment system components from burning. Begad! [Read More]


A permission granted by t' FAA t' launch large rockets into airspace that it controls, me hearties, for specific altitudes (usually 5000 or 10,000 feet) and for a specific period o' time. Avast, me proud beauty! [Read More]


A twist, usually undesired, arrr, in a normally flat object such as a fin [Read More]

Water Rocket

A rocket whose propulsion is derived by expellin' water; t' water may be propelled by compressed gas (normally air); t' compression may be derived from pumps (most commonly), pressurized tanks, or chemical reactions. Ya scallywag! Here are some o' them click here . Blimey! [Read More]

Watermelon Seed Effect

T' negative base drag (see "base drag") that can result when t' aft o' a movin' projectile is tapered such that t' airflow around t' projectile expandin' into t' space behind t' projectile presses against t' taper, providin' a small amount o' forward thrust. T' effect is similar t' ... [Read More]


T' tendency o' a rocket t' fly into a breeze, alterin' t' flight path from vertical. Begad! [Read More]


A method o' securin' fins by forcin' t' fin root in betwixt tubes in a motor cluster. Well, blow me down! [Read More]

Wind Tunnel

A specially designed pipe in which movin' air can be channeled in a controlled way, producin' an air stream o' laminar flow and constant velocity, thus allowin' testin' o' a design under constant conditions. Well, blow me down! [Read More]

Win' Loading

A method for measurin' appropriate win' size, calculated by dividin' t' win' area in inches squared by t' mass o' t' aircraft. [Read More]


Small fin or wing-like extensions attached t' t' ends o' t' wings o' an aircraft. Avast! [Read More]


T' linear distance betwixt t' extremities o' an airfoil; typically t' distance betwixt t' win' tips o' an airplane. Ahoy! [Read More]


In British usage, a rocket's fins. Also, matey, t' liftin' surfaces o' a glider. [Read More]


White Lightning; a propellant made by Aerotech; "A brilliant white flame, ya bilge rat, dense bright white exhaust, me bucko, and a throaty roar are t' hallmarks o' this popular propellant". Avast, me proud beauty! [Read More]

Wood Filler

A common filler for tube spirals, balsa fins, arrr, fillets, matey, etc. Ya scallywag! [Read More]

Wood Grain

T' predominant direction o' t' fibers in a piece o' wood. important t' note as t' strength o' t' material is perpendicular t' t' fiber direction. Begad! [Read More]


Windows Rocket Altitude Simulation Program; a public domain program that simulates t' flight o' a rocket in one dimension [Read More]

- X -

X-form Parachute

A parachute that is formed by connectin' together two rectangles o' material, formin' an 'X' [Read More]


t' 'X' stands for experimental; t' series o' US Government experimental planes startin' with t' Bell X-1. [Read More]


"T' X PRIZE is a $10,000,000 prize t' jumpstart t' space tourism industry...the $10 Million cash prize will be awarded t' t' first team that: Privately finances, me bucko, builds & launches a spaceship, arrr, able t' carry three people t' 100 kilometers (62.5 miles); Returns safely t' Earth; Repeats t' launch ... [Read More]

- Y -


Yet Another Born Again Rocketeer. Well, blow me down! See BAR [Read More]


A back-and-forth motion o' t' nose o' a rocket in flight, on t' axis determined as "left-and-right". Avast! See Pitch. Begad! [Read More]

- Z -

Zipper / Zippering

A condition in which a slot is cut in an airframe by a shock cord. This condition is caused by early or late recovery system deployment, in which t' recovery system deploys while t' airframe is movin' at a high rate o' speed. [Read More]


UK Term: A town in t' UK where rockets have zippers installed. Avast! [Read More]

# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

What You Can Do


DJI Mavic Pro-Fly For Miles, From Your Pocket.