Model Rocketry and Siege Engine Glossary Letter B


Model Rocketry and Siege Engine Glossary Letter B

Glossary
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Baffle
See Ejection Baffle
Ballast
Mass added to a model to bring the model into balance
Ballistics
Study of objects moving through the air that have been given a short lived acceleration.
Ballistic Coefficient
A rocket’s weight divided by its drag form factor. The drag form factor is equal to a rocket’s drag coefficient multiplied by its frontal area. The greater a rocket’s ballistic coefficient, the higher it can coast after finishing the thrust portion of its flight.
Ballistic Missile
A vehicle whose flight path from termination of thrust to impact has essentially zero lift. It is subject to gravitation and drag, and mayor may not perform maneuvers to modify or correct the flight path.
Ballistic Range
The range on surface of the reference sphere from the cutoff point to the point of reentry through the reference sphere
Ballistic Trajectory
The path a rocket takes when descending without benefit of parachute. Normally, unless acted upon by the wind, a rocket’s ballistic trajectory continues to describe a parabolic arc, bringing it to earth nose-first in a relatively predictable location
BALLS
Short for Big A** Load Lifting Suckers: A popular annual launch for amateur and large HPR rocket flyers
Balsa Wood
Fast growing wood from Central America known for strength, low density, and a very porous grain. Frequently used for model rocket fins
BAR
Short for Born Again Rocketeer. A person who once pursued rocketry as a hobby, and returned to it at a later time in life.
Barrowman Method
A mathematical technique for calculating the center of pressure of a subsonic rocket at low angles of attack. Named for James S. Barrowman, who developed the method in 1966
Base Drag
Drag produced by the airflow moving from the sides to the rear of a model. As the airflow reaches the rear of a moving rocket’s airframe, it separates from the rocket at the base. This creates a low-pressure region at the base of the rocket, and impedes its forward motion. During the powered portion of a rocket’s flight, base drag is reduced by the production of gases from the rocket motor
Baseline
The line between the tracker and the launcher in the single tracker method for finding altitude, or the line between to the tracking stations in the two tracker method
Basswood
North American hardwood known for very tight even grain and fairly good ease of working
BATF
Bureau of Alcohol Tobacco and Firearms; a federal regulatory agency. Sometimes called ATF.
Bay
part of a model set aside for a specific purpose such as the payload bay
Beam , Structural
A rigid body designed to transmit loads in shear or bending transversely to its point of support. A fin is actually a structural beam
Beacon, RADAR
Generally, a non-directional radiating device, containing an automatic radar receiver and transmitter, that receives pulses ("interrogation") from a radar, and returns a similar pulse of set of pulses ("response"). The beacon response may be on the same frequency as the radar, or may be on a different frequency
Beeper
A device that produces an auditory signal, assisting searchers to find a rocket after it has landed
B/G
Boost Glider
Bernoulli’s Principle
A physics principle that states the pressure exerted by air perpendicular to its direction of travel decreases with an increase in velocity
This is the theoretical principle upon which airplane wings work. An airplane wing’s airfoil is unsymmetrical, its upper surface having a greater curve than its lower surface. This causes air flowing across the upper portion of the wing to speed up, since it must cross a greater surface area in the same length of time. The increase in air velocity on the upper surface causes the air pressure in the region just above the wing to be reduced. The higher pressure below the wing presses upward on it, creating lift.
Birch
North American hardwood known for its pliancy and tight grain
BIPROPELLANT
A liquid rocket propellant that consists of a liquid fuel and a liquid oxidizer each separated from the other until introduced into the combustion chamber; also either the fuel or the oxidizer before being brought together
BIRD
A figurative name for a missile, earth satellite, or other inanimate object that flies
Black Powder
The original explosive, said to come from China. A mixture of carbon, (charcoal), sulfur and ammonium nitrate (saltpeter)
Blackshaft®
A trademarked name for thin-walled body tubing made from phenolic-impregnated paper and used on 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. Blackshaft tubing - so called because it was black in color - was sold by Apogee Components. In some circles it earned the derogatory name "blackshatter" due to its inability to absorb any lateral shock without breaking. Manufacture of blackshaft tubing was discontinued in 1994.
Blade
Long thin wing, rotated around a central hub, such as on a propeller
Blade Twist
The pitch angle variation on a helicopter blade from root to tip
Blast Deflector
A plate or other device that protects flammable materials like grass - surrounding a launch pad, from being ignited by rocket exhaust
Blister, Paint
Air bubble formed under a skin of paint. Usually caused by heat applied to that spot or improper/incomplete preparation before paint
Block House
A reinforced concrete structure, often built underground or half underground, and sometimes dome-shaped, to provide protection against blast, heat, or explosion during commercial or military missile launchings or related activities. Generally not needed for hobby rocketry
Booster
An auxiliary propulsion system which travels with the missile and which may or may not separate from the missile when its impulse has been delivered
Burnout
The time at which combustion in a rocket engine ceases
Blowthrough
The physical ejection of propellant through the front of the rocket body. See CATO.
Boat-Tail
A tapering section which reduces a rocket’s tail diameter, to improve aerodynamic efficiency through the reduction of base drag
Body Tube (BT)
A cylindrical tube that makes up the body of the rocket. Typically made of cardboard, fiberglass or carbon fiber. See Airframe
Bonus Delay
Slang for an unexpectedly long delay, sometimes resulting in airframe damage or parachute stripping. See Zippering.
Boost Glider
A winged aircraft which is powered into flight by a rocket motor, then returns to the ground as a glider after ejecting its motor or motor assembly. See Rocket Glider
Boost Phase
That part of a rocket’s flight in which the propellant is generating thrust
Booster
In a multi-stage rocket, the first stage. In a parallel staged rocket, the pods containing the motors with the shortest burn time. In a complex single-stage rocket, the term sometimes refers to the part that contains the motor assembly
BOR
Big Obnoxious Rocket
Boundary Layer
The very thin layer of fluid close to the surface of a solid in an airflow
BP
See Black Powder
Bridgewire
Part of an electric match; a thin wire that either heats up or melts when an electric current is applied. The resulting hear ignites a small amount of pyrotechnic material at the tip of the match
BSMA
British Space Modeling Association
BT
See Body Tube
Buckle
A bend or kink formed by overstressing the airframe
Buffeting
Repeated forces experienced by a model due to disturbed unsteady airflow
  • A term used to describe a rocket kit that is or may be very difficult to assemble and or finish
  • A term used to describe rocket kits produced for sale without proper parts and requiring experience modelers to finish.
Built-Up
a hollow component, such as a fin, made up of a number of structural parts
Bulkhead
A solid partition in the rocket, especially one set perpendicular to the rocket’s long axis, designed to not allow gases to pass
Bungee
Round, woven elastic material, often used as shock cord in high power rockets
Burn
The chemical reaction that occurs within a rocket motor producing a high velocity gas
Burn Rate
The rate at which a substance is consumed by burning, such as propellant or a fuse
Burn Time
The time that it takes for a motor to fully expend its fuel
Burnout
The point at which propellant is exhausted in a motor
Burnout Velocity
The velocity of a rocket at the end of propellant oxidation. (See cut-off velocity)
Butt Joint
A joint made by gluing an edge to a surface, such as a fin to a body tube


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