Rocketry Terms

advanced rocketry - Rocket activities involving vehicles having a lift-off weight in excess of 1500 grams and/or having one or more motors containing more than 62.5 grams of propellant each. Said vehicles shall not have nose cones, airframes, motor mounts, or fins constructed of metal. This does not apply to payloads.
aft - is the rear-ward end of something on a rocket. Ship terminology is often used because "top" and "bottom" are confusing as orientation changes. See also forward.
AGL - Above Ground Level. When talking about an altitude waiver, refers to the maximum altitude you can legally fly under that waiver. It is usually added to the MSL (Mean Sea Level) altitude of the launch site to give an altimeter reading that pilots must avoid.
air start - Any motor that is fired after first motion of the vehicle.
airframe - The rocket structure. This usually refers to just the cylindrical body tube, but may also refer to the entire body of the rocket.
amateur rocketry - Any and all rocketry activities thus far not covered, not funded by a professional entity, and not conducted for monetary purposes. Generally considered for motors beyond P and all liquid fuels.
ammonium perchlorate (A.P.) - Composite (mid- and high-power solid fuel) motors are generally made with ammonium perchlorate as the oxidizer and various other ingredients as the fuel.
altimeter - is a device which measures at least the maximum height a rocket reaches. These are often combined with circuitry to separate the rocket at apogee for recovery.
apogee - is the highest point of a rocket flight. An ideal rocket flight opens the rocket and ejects the recovery system at apogee.
Association - A body of persons connected to each other as in some business, interest, or position.
ATF – Bureau of Alcohol Tobacco and Firearms.
Away Cell - An launch area away from the general launch area and spectators reserved for special and large projects.
BALLS - Tripoli National Experimental Launch held annually. Not an acronym for anything. This is a launch where gutsy, creative and experimental rockets are launched powered by motors greater than K power.
B.A.R. - A Born Again Rocketeer is someone who flew model rockets (usually Estes) as a child and has returned to the hobby as an adult. Generally B.A.R.s re-enter the hobby after discovering it on the Internet or after seeing the movie October Sky.
BATF – Bureau of Alcohol Tobacco and Firearms.
black powder (B.P.) Black powder (model rocket solid fuel) motors are generally made with black powder (oxidizer and fuel). Note the black powder can't be used for reliably motors larger than "D" and "smokeless powder" (gun cotton) cannot be used at all.
BLACK POWDER MOTOR – Rocket motors using black powder as fuel.
BLM – Bureau of Land Management.
body tube - A cylindrical tube that makes up the body of the rocket. Typically made of cardboard, fiberglass or carbon fiber.
caliber - is the diameter of the main body tube of the rocket in question. For example, rockets are commonly 15-25 calibers in length. (This term comes from gunnery where caliber is the outside diameter of the shell.)
CATO - means that a motor blows up! This is rare for production pre-manufactured motors, but amateurs will encounter it.
center of gravity (C.G.) - is the balance point of the rocket with the intended motor loaded. You can measure the C.G. directly on a finished rocket by installing the motor and finding where it balances on an edge (like a see-saw).
center of pressure (C.P.) - is the balance point of aerodynamic forces on the rocket. You can calculate the C.P. using various rocket simulation programs. If the C.P. is not well aft of the C.G., the rocket will not be stable.
centering ring - A plate used in a body tube to center a motor tube or strengthen a section of body tubing.
CERTIFIED MOTOR LIST
High Power Motors
NAR Certified Motor List
CERTIFICATION
- Level 1
- Level 2
- Level 3
class B motors – Rocket motors containing more than 62.5 grams of propellant or motors that impart more than 120 Newton-seconds of thrust.
class C motors – Rocket motors contain less than 62.5 grams of propellant or impart 120 Newton-seconds of thrust or less.
clustering - A technique which uses 2 or more motors side by side in the same rocket.
code - A recommended guide not to be interpreted as the letter of the law.
CD Coefficient of Drag - A numerical value indicating the amount of drag a rocket will encounter in flight.
COMPOSITE MOTOR – A rocket motor made of Ammonium Perchlorate, rubber, metals and other components.
coupler - A body tube used to connect 2 sections of larger body tubing.
CPSC – Consumer Product Safety Commission. Rules restrict use of HPR motors (H and up) to adults 18 years of age and up.
distributor - A person or company that purchases products in a large quantity, divides into smaller quantities, and makes said product available to others. A Distributor shall have a Business Address, Business Phone, and Business License.
DOT – Department Of Transportation.
educational rocketry - Rocketry activities conducted to teach or learn already known knowledge and/or concepts of rocketry principles.
ejection -The charge (or sometimes mechanical system) which opens the rocket at apogee to deploy the recovery system. The ejection delay is the amount of time between motor burnout and the deployment and it timed to occur at apogee.
engine - A machine that converts energy into mechanical work.
EXPERIMENTAL ROCKETRY - In Tripoli context, flights using non-certified or flyer manufactured motors.
FAA – Federal Aviation Administration.
FAR101 - FAA regulations regarding airspace use for model rocketry.
fins - (you knew this one) are the flat parts which stick out from the tube at the aft end of the rocket and provide stable flight. Without fins (or other special arrangements), the rocket will not fly in a straight line.
fin canister - A section of body tubing with the fins mounted in it. (fin can)
forward - is the front end of something on a rocket. Ship terminology is often used because "top" and "bottom" are confusing as orientation changes. See also aft.
HPR - High-power Rocketry, Any rocket activities using motors with a Total Impulse of 160.01 N/s or more.
HYBRID MOTOR – A binary fuel motor. Typically in HPR; Nitrous Oxide and cardboard or plastic.
igniter - An electrically actuated device used to start ignition of the rocket motor.
IGNITER PREP AREA - An area between the LCO and launch pads designated for the installation of igniters prior to flight.
ignition - Solid-fuel motors are ignited electrically using an "ignition system." An "igniter" is inserted into the motor and when electricity is passed through it, it bursts into flame, igniting the motor. This allows the motors to be launched with everyone at a safe distance.
impulse - is the measure of thrust over time (in Newton-seconds or pound-seconds of force). The "total impulse" of a motor is the amount of energy it provides to lift the rocket and the source of the letter designation ("A, B, C" and so on).
ITAP – Interim Technical Advisory Panel. Set up at the beginning of the conversion to the multi-level certification program. Phased out in 1998.
land shark - A rocket, that for whatever reason, comes off the launch rod, fails to attain air flight, and slides along the ground under power.
launch lug - A piece(s) of hardware usually on the side of a rocket used to attach the rocket to a launch rod or rail guide.
launcher - A launcher is required to hold the rocket in a vertical position and guide it straight during the beginning of its flight (before the rocket gains enough airspeed for the fins to take effect). The most common kind of launcher is a base with a thin steel rod to which the rocket attaches with a "launch lug."
LCO - Launch Control Officer. Person in charge of controlling the range and launching rockets. The LCO must make sure that the range is clear and the skies are clear. This person shall not launch a rocket when the flight will carry it within 1000 feet of clouds, if an airplane is within 5 miles of the launch area or when people are in the range area. The LCO will call for a "heads up" for any large project, cluster rocket, multi-stage rocket or if the RSO deems it necessary for any given flight. The LCO at his discretion shall call for "everyone on their feet standing" on heads up flights. The LCO should provide an account of the flight on the loudspeaker and follow it if possible, to verify that the is nominal (parachute is out) and provide the necessary warnings for a non-nominal flight (i.e. stripped parachute or rocket landing in the spectator area. If any events occur after the launch of the rocket (i.e. fire or other mishap), the LCO will close the range and call for assistance.
LDRS - Tripoli National Launch held annually. Stands for Large and Dangerous Rocket Ships.
LEUP – BATF Low Explosive User Permit for rocket motors with greater than 62.5 grams of propellant.
Level N - "Level 1" refers to rockets which use H & I motors, "level 2" to J through L motors and "level 3" to M through O motors.
low power – Typically rockets flying on motors in the A to D range.
manufacturer - A person or company who makes or processes a product, especially on a large scale and with machinery. A Manufacturer shall have a Business Address, Business Phone, and Business License.
mid power rocketry – Typically rockets flying on motors in the E to G range.
model rocketry - An aero-vehicle that ascends into the air without the use of aerodynamic lifting forces against gravity. The gross launch weight, including the motor(s), will not exceed 1500 grams. Motors for said vehicle will not exceed 160 newton seconds of impulse and/or contain more than 62.5 grams of propellant each, and no more than a total of 125 grams of propellant in multiple motor situations. All components of said vehicle shall be of wood, paper, rubber, breakable plastic or similar material and without substantial metal parts.
ModRock - Model Rocketry.
motor - The motive force making a rocket go. Solid fuel rockets use motors because there are no mechanical moving parts (they're not engines).
MOTOR CODE - Describes a given motors performance. Example: "H128-10" where the H stands for the total motor impulse in the range for an "H" motor (160ns to 320ns), the "128" is the average thrust in newtons per second and the "-10" is the delay time in seconds.
Motor tube - A section of body tubing in which the motor slides into.
multi-staged rockets - A multi-stage rocket has different sections, each of which has its own motor.
NAR – National Association of Rocketry
NFPA - National Fire Protection Association - Private corporation for setting safety standards.
NFPA 1122 - Code for Model Rocketry.
NFPA 1125 - Code for Motor Manufacturing.
NFPA 1127 - Code for High Power Rocketry.
nitrous oxide - The liquid fuel portion of a hybrid motor.
nose - The forward end of a rocket. The tapering (pointy) part of the rocket is often referred to as a "nose cone," even though the shape is rarely conical.
nose cone - A part that is at the top of the rocket usually of conical shape.
October Sky - is an excellent movie about a group of boys in a coal town in West Virginia who build their own rockets. October Sky is responsible for much new interest in the hobby. The book Rocket Boys by Homer Hickam, Jr. is even better than the movie (October Sky was based on Rocket Boys).
orange book – BATF explosives rule book.
pad manager - Person responsible for assigning pads and controlling the launch pad area. Helps rocketeers set up pads and rockets for flight.
parachute - ('chute) The most common rocket recovery system and the only one used with larger rockets. Model rocket often use flat plastic "parasheets" which are attached to the rocket with thread. Larger rockets use true parachutes because of the weight being recovered.
potassium perchlorate – Oxidizer used in some military composite motors.
prefect - The head of a Prefecture, or the designated person, to maintain a line or communications with, or to see compliance to, the over-organization.
PREFECTURE - A group of people formed locally, as a self-governing, supporting unit of a larger organization.
publication committee - Tripoli committee responsible for directing and/or producing HPR Magazine, Tripoli Report, Web Page, Member Binder and other written or printed documentation.
range head - Generally the LCO table and launch control.
recovery - Rockets must be recovery safely. If a rocket comes down without a recovery system, it will fall nose down very fast and will be dangerous. Getting your rocket back in once piece is important as part of a successful flight (not to mention that it allows you to fly again). The most common recovery systems are parachutes and streamers although many others have been devised.
research rocketry - Rocketry activities designed to discover, test, or to illustrate a truth, principle, or effect.
RSO - Range Safety Officer. Person(s) responsible for field safety. Determines suitability of rockets to fly at a particular site. Inspects rockets prior to flight. The RSO should be a Level 2 certified flier. Upon inspecting a rocket for flight the RSO needs to check for: suitability of a particular motor/rocket combination, inspect the recovery system, motor retention, construction, launch guides, electronics and any other items he feel necessary. For scratch built rockets the RSO can additionally request location of CP/CG and launch parameters. For level 3 certification flights the RSO is guided by the input from the onsite TAP member that must inspect the rocket prior to bringing the rocket to the RSO. The RSO may reject any rocket for flight for any reason if deemed to compromise the safety of the launch, launch area or spectators.
scratch built - A rocket that is not of commercial design (i.e. home made or home designed).
shred - When a rocket breaks up in flight, it's called a "shred." Rockets shred because they aren't stable, too large a motor is used for the materials, or they have not been properly constructed.
separation - When the recovery system comes out too early or too late and the rocket is still moving too fast, the recovery system takes a strong jerk. If it breaks, the two parts become detached and you have a separation.
socity - A system of individuals formed as a continuous and regulatory association for their mutual benefit and protection.
sport rocketry - Rocketry activities pursued as a pastime, diversion, or personal enjoyment.
stability - Hobby rockets almost always depend on fins and balance to guide the rocket in a straight line. A particular rocket is stable on a particular motor if it will launch and fly in a straight line. This becomes quite a complex topic.
storage magazine - An ATF approved type 3 or 4 storage magazine is used for the storage of class B rocket motors.
streamer - A recovery system for the smallest of model rockets. Streamers are flat plastic, paper or cloth bands which are attached to the rocket and flap as the rocket comes down, slowing the descent.
TAP – Technical Advisory Panel. Members on this committee review and certify Level 3 flights.
thrust - is a measure of instantaneous force (in Newton's or pound of force). The "average thrust" of a motor is the average amount it pushes on the rocket during it's entire burn phase. Note that the motor generally produces different amounts of thrust as it burns and a graph of this is called a "thrust curve."
TMT - Tripoli Motor Testing Committee. A brief History and Restriction List.
weathercock - The tendency of a rocket to fly into the direction of the wind, altering the flight path from vertical.
wind tunnel - A testing device in which moving air can be channeled in a controlled way, producing an air stream of laminar flow and constant velocity, thus allowing testing of a rocket design under constant conditions.
wood grain - The predominant direction of the fibers in a piece of wood. The strength of the material is perpendicular to the direction of fibers.
yaw - A back-and-forth motion of a rocket in flight, on the axis determined as "left-and-right".
zipper - A situation where a slot is cut in an airframe by a shock cord after deployment. This is caused by early or late recovery system deployment, in which the recovery system deploys while the airframe is moving at a high rate of speed and the shock cord or attachment "zippers" down the side of the airframe.