Article 23984 of rec.models.rockets:
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From: rml!jack@lll-winken.llnl.gov
Subject: Glossary, K thru Z
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Date: Sat, 26 Nov 1994 21:10:26 GMT
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Kato           See "Cato"

Kicked         A term used to describe a motor which is ejected from the 
	       rocket while in flight.  This often results in the failure of 
	       the recovery system. It is usually caused by not fitting the 
	       motor into the motor mount properly. See also "Prang"

Kitbash        Taking two (or more) kits and combining ("bashing") them into
               a new design. Often used as a contest event (Team Kitbash, where
               teams compete, Kitbash Duration, Scale Kitbash, etc) where the
               idea is to be creative in a limited amount of time.

	    Origin:
	       The term appears to have come from the model railroading hobby
	       where kits for buildings and other diorama items have, for 
	       decades, been modified from their original intent to suit the 
	       needs of a particular layout.

Krushnic       A very dramatic phenomenon where your rocket makes a tremendous
Effect         amount of noise and smoke but doesn't go anywhere! This happens 
	       when the motor is recessed into the body tube by more than one 
	       tube diameter. If so recessed, the cylindrical volume below the 
	       motor forms a secondary expansion chamber which allows the 
	       exhaust gasses to expand below atmospheric pressure before 
	       leaving the rocket. Surrounding air aspirated into the exhaust 
	       stream causes turbulence which negates much of the thrust, along 
	       with creating the characteristic roar. A multi-stage model that 
	       ejects its booster motor, but not the airframe, is a perfect 
	       example. Very damaging; it almost always destroys the lower body 
	       tube beyond use. Named for Richard Krushnic, the rocketeer who 
	       characterized the effect in the late '60s. Not to be confused 
	       with "Suction Lock" (q.v.).

Land Shark     A rocket which has failed in such a way that it ends up on
Worm Burner    the ground while still under power.  Upper stages of unstable
               multi-stage rockets often end up like this, as do some (too)
               heavy HPR rockets with long-burning, low thrust motors.

Landis Loop    A ring used in a tower launcher to keep the back end of a 
	       egglofter centered during launch. Invented by Geoff Landis 
               and named for him by Bob Kaplow. 

LCO            Launch Control Officer: the individual responsible for safe 
	       operation of the launch range.  

LDRS           The annual national high power sport launch sanctioned by 
               Tripoli.  LDRS stands for 'Large Dangerous Rocket Ships,' the 
	       derivation of which is best left to others. Note: LDRS has NEVER 
	       stood for 'Lets Do Rocketry Safely', despite what you hear from 
	       historical revisionists trying to mollify public officials :-) 

Lovelace       A phenomenon where the nose cone is apparently "sucked" out of 
Effect         the body right at motor burnout. It is more prevalent on para-
	       bola, ogive and other low drag nose shapes. The theory (as yet 
	       unproven) is that since the nose cone has much less drag than 
	       the body, its momentum tends to carry it forward faster (or, 
	       more correctly, the body's drag decelerates *it* more quickly) 
	       putting tension on the nose-body joint. The condition is 
	       exacerbated by any nose weights added for stability (which 
               also raise the momentum of the nose) and/or a loose fit of 
               the nose in the body.

               Another possible contributing factor could be the denser air 
	       (trapped in the body tube from ground level) exerting pressure 
	       on the nose cone once the rocket reaches a higher altitude.

               The term is named after an early '70s movie actress 
               who, ahh, um...well, go ask your dad :-)

Magnelite (tm) An ignitor made by Rocketflite used mainly to start composite 
               motors. A medium power device (2-3 amps at 12 volts), it requires
	       significantly more than an electric match (q.v.), but not as much
	       as a Copperhead (q.v.). It consists of a nichrome bridgewire 
	       dipped in a magnesium based pyrogen which burns *very* hot 
	       (~6000F), aiding in the ignition of stubborn composites, such 
	       as a "Blue Thunder". They come both single and double dipped,
	       depending on how much "oomph" you need. The head is quite large
	       so they work best in 29mm and larger motors.

Medium Power   See "HPR Lite"
Rocket         

Midwest        During the 1970's, NAR contest flyers circulated a persistent 
Qualified      rumor that meets held on the East Coast were held to a much  
               higher standard of flight qualification than those flown in the 
	       Midwest. The Contest Board steadfastly maintained that contest 
	       rules were uniformly enforced. The differences in flight 
	       qualification occasionally surfaced at NARAM. If an RSO qualified
	       a flight that many people felt should not have been, his or the 
	       flyer's geographical location came under scrutiny. While no rule 
	       changes or procedures were modified, flyers continue to refer to 
	       those marginal flights squeak through as "Midwest Qualified." 
	       
	       The term also gained popularity when a group of competitors from 
	       the SNOAR section in Cleveland began offering at NARAM the 
	       "Best Midwest Qualified Flight" award. A collection of wreckage 
	       of NARAM's prangs, large and small, were attached to a large 
	       sheet of cardboard, along with local flora, fauna, tourist 
	       brochures, food wrappers, etc. SNOAR members then decided who 
	       had the best prang of NARAM, and presented the "trophy" to the 
	       "winner" at the  awards banquet. Nomination was cause for pain 
	       enough, but winning made one a legend in his own time.

MIF            Missing In Flight. A rocket that disappears with no sign of the
	       recovery system deployment, and no other obvious failure mode
	       (e.g. Prang or CATO). Sometimes called "into orbit."

Minimum        A rocket built with the smallest possible diameter body tube for
Diameter       the size of motor casing. Usually done to reduce drag in sport or
	       competition models even though it can increase the difficulty of
	       attaching fins and recovery systems. See also "Boosted Dart"

Model Rocket   An aero-vehicle that ascends into the air by means of a 
 	       reaction motor, but without the use of aerodynamic lifting 
	       surfaces. The restrictions, as defined in NFPA 1122, are as 
	       follows: The gross launch weight, including motor(s), will not 
	       exceed 1500 grams. Motor(s) will not exceed 160 NS of impulse 
	       (total) 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 applications (clusters and/or multi-stages). 
	       
	       All components of said vehicle will be of wood, paper, rubber, 
	       breakable plastic or similar material and without substantial 
	       metal parts. See also "FAR 101" and "NFPA 1122"
 
Model          The original NAR newsletter. Published as an insert to MRM 
Rocketeer      (q.v.) while it lasted and thus available to non NAR members 
               for a while. After MRM folded, it was again published stand-alone
	       and gradually expanded to a magazine style format.  It became 
	       *American Spacemodeling* (q.v.) in July 1984, although there 
	       continued to be a section called "The Model Rocketeer" for the 
	       NAR president's column and other association news (just like in 
	       MRM!) which became the "President's Corner" in 1992.

Modroc         Model Rocket.  Also seen as 'modrocer', or similar spelling,
               to mean 'model rocketry enthusiast'.

Monopropellant See "Single Base Propellant"

Motor          Something that imparts or produces motion, such as a machine
               or engine. A device that converts any form of energy into
               mechanical energy (from *American Heritage Dictionary*).
	       See discussion at the end.

MRM            Model Rocketry Magazine - An early attempt at a "newsrack" 
               style rocketry magazine. It attempted to do for rocketry
	       what *Model Railroading* did for that hobby or *RC Modeler*
	       did for model airplanes, namely create a forum where the whole
	       industry could talk directly to the hobbyist without limiting
	       him to a single company (e.g. the MRN or AR) or making him 
	       join an organization (e.g. the NAR). What it actually proved
	       was how tiny the hobby was back then as it only lasted a bit 
	       over three years from 10/68 through 1/72 then quietly folded. 
	       Notable on the staff was a young Jay Apt, who went on to join 
	       the astronaut corps and has made several Space Shuttle flights.

	       Despite the crude graphics and generally marginal production
	       values, the magazine was treasured by its small band of 
	       followers and copies are in great demand today. Photocopies
	       are circulated by an "old boy network" at meetings and swaps.

	       While it lasted, it also incorporated *The Model Rocketeer* 
	       the NAR newsletter which later became *American Spacemodeling*
	       and still later *Sport Rocketry* (available off the rack in 
	       larger hobby shops).  *HPR Magazine* (q.v.), the Tripoli journal,
	       likewise started as a captive publication for TRA which was later
	       taken private by its current editor. Thus we now have TWO
	       rocket hobby magazines on the newsracks today!

MRN            The Model Rocket News - The oldest continuously published
               rocketry periodical. Started by Vern Estes and his small
	       crew in 1960, it is still sent to all of Estes's active mail 
	       order customers. Somewhat sophomoric in style, it contains a 
	       great deal of practical information, especially for beginners. 
	       It has survived a bewildering array of changes in format over
	       the years, but is still published three or four times annually. 
	       Current editor: Mike Hellmund.

NAR            National Association of Rocketry. A national hobby organization
               promoting model and high power rocketry in the United States.
               The NAR promotes rocketry related sport flying, competitions,
               and education. 

NARAM          National Association of Rocketry Annual Meet.  The NAR 
               national championships competition, held in August of
               each year.

NARCON         National Association of Rocketry Annual Convention.  An annual
               event sanctioned by the NAR oriented towards non-competitive
               (i.e., sport) model and high power rocketry. It includes
               seminars, R&D presentations and lots of sport flying.

NARTS          National Association of Rocketry Technical Services.  A service
               provided by the NAR for both members and non-members.  NARTS
               stocks rocket plans, technical reports, and other items of
               interest to rocketry enthusiasts.  NARTS may be reached at
                    NAR Technical Services (NARTS)
                    P.O. Box 1482
                    Saugus, MA 01906
                    CompuServe account: 73320,1253

Newton &       Metric units used to measure thrust and total impulse (q.v.)
Newton-second  respectively. One pound = 4.445 newtons. 

NSL            National Sport Launch.  An annual, national sport fly
               sanctioned by the NAR.  It is currently held in February
               of each year so that it is midway between NARAM national
               meets.

NFPA           National Fire Protection Association.  A private for-profit
               organization responsible for crafting rules and regulations 
               dealing with fire safety issues which are beyond the expertise 
	       of local agencies. The NFPA is NOT a government agency and has 
	       no enforcement power of its own. It gathers experts in various 
	       fields to write safety regulations for adoption by local fire 
	       agencies (at the discretion of the Fire Marshal). The current 
	       NAR Model Rocket Sporting Code was developed by the NAR and NFPA.
	       Both the NAR and Tripoli are members of the NFPA.  G. Harry 
	       Stine ('the old rocketeer') is currently the chairman of the 
	       pyrotechnics committee of the NFPA.  

NFPA 1122      The current NFPA regulation defining Model Rocketry. This
	       document defines a model rocket as having less than 1,500 grams
	       total launch weight, containing less than 125 grams of fuel (no
	       more than 62.5 grams in any one motor), and no more than 160NS 
	       total impulse in all motors (no individual motor having more
	       than 80NS of total impulse).  

NFPA 1127      The NFPA regulation defining High Power Rocketry. The draft
	       provisions of 1127 (not yet ratified) defines HPR as follows:
	       High power rockets have no total weight limits, but do have a 
	       single motor limit of no more than O power (40,960 NS total 
	       impulse) and have a total limitation of 81,920 NS total impulse.  
NXRL           The National Experimental Rocket Launch. An annual launch 
	       sponsored by Tripoli and hosted by AERO-PAC (q.v.) for the 
	       purposes of launching very large (K and above) HPR birds. An 
	       outgrowth of FIREBALLS (q.v.), Tripoli "adopted" the concept to 
	       provide insurance and continuity on an annual basis. The main
	       difference between NXRL and other Tripoli launches (e.g. LDRS,
	       Danville) are that no rockets *below* K power are permitted 
	       (which holds down the crowd) and that home made motors are 
	       allowed as long as they conform to the basic HPR safety code.
 
Ogive          A shape defined by the intersection of two circles. It is not 
	       the same as a parabola (q.v.). Both ogives and parabolas produce 
	       low drag sub-sonic nose shapes. They can be told apart since a 
	       parabola always has a rounded nose while an ogive comes to a 
	       point.

Olympic Torch  A rocket that power prangs (q.v.) with the motor still burning.
	       Coined by Bob Kaplow after almost impaling NAR President Mark 
	       Bundick with an RMS (q.v.) powered model that suffered a nozzle
	       failure which dropped the thrust to zero even though the motor
	       kept burning.  See also "Roman Candle" 

Optimum Mass   For any given motor and Drag Form Factor (q.v.) the liftoff 
	       mass for which a rocket will reach maximum altitude in dense 
	       atmosphere. At first this might seem to be just the lowest 
	       possible mass, but there is a two edged nature to mass covering 
	       both powered flight and coasting. Lower mass will give higher 
	       burnout velocity, but will dissipate its momentum to drag faster 
	       (think of a feather). Conversely, a heavier rocket will have 
	       more momentum at burnout to coast farther, but too much mass 
	       will hold down both burnout altitude and velocity. Hence, there 
	       is a "knee" on the liftoff mass vs. altitude graph.

	       For very low impulse motors (say "B" and below) this "knee" is
	       right around the mass of the motor itself, so the rule of thumb 
	       is "the lighter the better." The higher impulses, though, have
	       more leeway, and careful calculations should be made to determine
	       the optimum mass for altitude attempts. 

	       In a multi-stage rocket with no staging delays, only the dead
	       mass in the upper stage participates in coasting. Extra dead 
	       mass in lower stages cannot enhance coast distance, and so 
	       lower stages should be as light as possible. Strictly speaking, 
	       an undelayed staged rocket has no optimum liftoff mass, but 
	       the mass of the last stage may be optimized with respect to the
	       (sub-optimal) lower stages. In dense atmosphere, the best single
	       stage configuration is more efficient than the best multi stage 
	       configuration, provided all the propellant can be contained in 
	       one stage. Indeed, there are many instances when cluster rockets 
	       out perform staged rockets.
	       
	       The opposite is true for rockets operating in the thin atmosphere
	       of high altitudes. In that environment, staged rockets are more 
	       efficient (propellant-wise) than single-staged rockets, and 
	       lighter rockets always perform better. There is no optimum mass 
	       in a complete vacuum.
	       
Pacific        An experimental rocket organization which experiments with
Rocket         amateur rockets both solid and liquid fueled, although mostly the
Society        latter. It is a very old organization by hobby standards with 
(PRS)          roots dating back to the '50s thus predating hobby rocketry in 
	       its current form. They launch in the Mojave Desert from facili-
	       ties leased from the Reaction Research Society (q.v.). Their
	       mailing address is: 
			Pacific Rocket Society 
			1825 Oxnard Blvd., Ste. 24 
			Oxnard, California 93030

Parabola       A shape produced by the formula y=x^2. Used to produce low
	       drag nosecones. See also "Ogive"

Payload        Anything carried aloft by the rocket that is not part of the 
	       rocket itself. Common payloads include altimeters, computers,
	       cameras, and radio transmitters.  The Safety Code specifically 
	       prohibit the launching of live payloads.  

Phenolic       A heat-resistant plastic most familiar as the material from which
               plastic ashtrays are made. It is made by a reaction of phenol 
	       and formaldehyde. When mixed with carbon black, it is used to 
	       make casings for composite propellant rocket motors. It is also 
	       used to reinforce the cardboard in body tubes for competition 
	       rockets (e.g. "Blackshaft" tubing sold by Apogee). Phenolic body 
	       tubes are stiffer than ordinary tubes, but are also more brittle                so that extra care must be taken to avoid damage during 
	       construction, transportation and recovery.

PMC            Plastic Model Conversion.  The term used to describe a plastic,
               static model of some type (typically an aircraft, rocket or
               spaceship) that has been converted to fly as a model or
               high power rocket.  This term is also used as an abbreviation
               for an NAR-sanctioned competition using converted models.

Prang          Term describing a failure mode whereby a rocket comes down 
               aerodynamically stable, in other words, 'streamlines in'.  This 
	       is almost always caused by some sort of recovery system failure, 
	       usually the result of a too-tight nose cone, too-tightly packed 
	       parachute or a too-loose motor that ejects out the back.  Multi
	       stage models with upper stage ignition failures also result 
	       in a prang. 

               The results of a prang range from no damage at all (other
               than a few grass stains) on lightweight sport models to
               the total destruction of the rocket (usually a payloader 
               with a VERY expensive payload on board :-(.

               A prang that occurs while the motor is still burning (e.g.
               a marginally unstable rocket that performs one large half 
	       loop) is called a 'Power Prang'.  
	       
	    Origin:
	       If you insist on it being an acronym, the postwar military 
	       sounding rocket program had a quasi-official failure mode
	       category "Parachute Recovery Apparatus No Good." However, like 
	       CATO (q.v.), this is another "Post Hoc" definition. The term was
	       in widespread use during WW II in aviation circles to describe
	       aircraft crashes, especially experimental or military ones. Prior
	       to use in the U.S., it was popular in Britain since at least the 
	       '30s where the expression "Prang his Kite" was equivalent to our
	       "Auger in" or "Buy the Farm."

Prototype      An initial, development design used to test out principles and 
	       concepts but never intended to be a finished or production
	       design. In scale modeling, the original "real" rocket after 
	       which the model is patterned.
	       
	    Origin (in the modeling sense):
	       The term comes from model railroading where hobbiests model
	       sections of entire railroads including whole towns, mountains,
	       lakes, etc. in addition to the engines, cars and tracks. See
	       also "Scale Data" and "Scale Plan"

RASP	       The Rocket Altitude Simulation Program. Originally written by
	       G. Harry Stine in BASIC in the late '70s (and included as an 
	       appendix in the later editions of the Handbook), it performs a 
	       simulation of rocket flight using small time interval approxima-
	       tions. The original was relatively primitive assuming constant 
	       Cd, vertical flight and other simplifications. There have been 
	       several rewrites into "C" and other languages to both broaden 
	       its appeal and increase its sophistication.

Reaction       One of the oldest amateur rocketry organizations. Founded in
Research       1943, members of this Southern California group investigate all
Society        forms of reaction based vehicles: solid/liquid/hybrid. Their cur-
(RRS)	       rent very ambitious plans include orbiting the first *completely*
	       amateur satellite with a vehicle based on the "10K" (10,000 lb 
	       thrust) LOX/Kerosene motor now in development. 
	       
	       They have the decided advantage of *owning* their Mojave desert 
	       launch site which is adjacent to Edwards Air Force Base and thus 
	       protected by their "infinite" restricted airspace.  They lease 
	       the use of their launch facilities to the Pacific Rocket Society 
	       (q.v.) and welcome HPR fliers to come down and fly anything as 
	       big and high as they want as long as it's 1) prearranged and 
	       2) you play by *their* safety procedures. For more info there is 
	       a message on the Pacific Energy voice mail system which can be 
	       accessed after 6 PM (Pacific time) on weekdays and any time on 
	       weekends (213) 725-1139, ex 777. PR co-ordinator: Niels Anderson.
	       Mailing address is: 
			Reaction Research Society 
			P.O. Box 90306 World Way Postal Center 
			Los Angeles, California 90009

Red Baron      A boost glider which has tangled with the streamer or 
               parachute of the booster pod.  The entire model tends to 
               nose dive into the ground, like a WWI airplane which has 
               just been shot down.

Reef           A series of techniques used to gather the shroud lines of a 
               parachute together to prevent it from fully opening. This is 
	       usually done on rockets that reach extreme altitudes or launched 
	       on windy days which need higher sink rates to help them land 
	       near the launcher. There is also a "traveling reef" technique 
	       of placing a soda straw or metal washer on the shroud lines and
	       sliding it all the way up to the chute canopy during prep. At
	       deployment, the parachute is prevented from opening until the
	       chute is fully deployed and the rocket stabilized beneath it. The
	       straw/washer then slides down the shrouds allowing the canopy to 
	       open gradually. This is used mostly on large rockets which might 
	       have very high speed or high altitude recovery deployment since 
	       it allows the rocket to slow and drop considerably before chute 
	       opening. 

Re-Kitted      A (painfully) humorous term that refers to any situation 
	       where a rocket goes to pieces such as a prang (q.v.) or a 
	       CATO (q.v.). Thought to have originated at LDRS XIII. Typical
	       usage: "That E-15 sure re-kitted my Black Brant!"

Reynolds       A dimensionless number used by fluid flow engineers to character-
Number (Rn)    ise the way a fluid (gas or liquid) will behave when passing
	       over a solid surface. The number combines the fluid's density,
	       viscosity and velocity with the length it's traveled along the
	       surface. No matter what the fluid is or what size the surface, 
	       the flow conditions (laminar, turbulent, detached, etc.) should 
	       be the same at the same Rn. Discovered by Osborne Reynolds in
	       the 19th Century while studying the flow of water in pipes and
	       channels, it has proven most useful to aerodynamic engineers and
	       naval architects in scaling up wind/water tunnel test results to
	       full size.  
	       
	       Carl Dowd, a model aviator and NASA engineer, found it helpful 
	       to think of Rn as the "coarseness" of the air seen by a body. 
	       Move the body faster, and more particles will pass over it in 
	       a given unit of time, increasing Rn. Make the body larger, and 
	       there will be more particles over the body at any instant, 
	       increasing Rn. 

R/G            Rocket glider. A glider which is boosted to altitude by a 
               rocket.  The entire model glides down together.  No part of the
               model separates, as in a boost glider.  Technically, an R/G is
               a particular form of B/G.

RMS(tm)        Reloadable Motor System.  The trademarked name of the AeroTech/
               ISP reloadable motors.  Often used (incorrectly) as a generic
               name for all reloadable technology.  
	       
	       
Rocket and     An organization in Holland that supports both model and amateur 
Space          rocketry and amateur astronomy. It is currently trying to arrange
Foundation     a Get Away Special container for a space shuttle flight. The
               Secretary is Marcel Verhoef, Delft University of Technology,
	       who can be reached at:
			Rocket and Space Foundation 
			P.O. Box 314 
			3350 AH Papendrecht 
			The Netherlands 
			Internet: marcel@dutct05.tudelft.nl

Roman Candle   A failure of the motor restraint (thrust ring or engine hook)
	       where the rocket stays on the pad while the motor flies out of
	       the body (usually pushing the nose cone and recovery system 
	       ahead of it). Sometimes mistaken for a CATO (q.v.).

RSO            The Range Safety Officer, the individual responsible for 
	       ensuring that rockets presented for launch are properly 
	       constructed, prepped and balanced for stability.  

Safety Nazi    A person overly concerned with safety to the point of detracting
	       from the enjoyment of the hobby. Someone who feels the Saftey
	       Code doesn't go "far enough" in preventing injuries dispite the
	       hobby's outstanding safety record.

St. Louis      The trajectory of a Prang (q.v) when viewed from a distance.
Arch           Named for the famous monument whose shape it mimics. Popularized
	       at NARAM 36 by Peter Alway who had driven through St. Louis on
	       his way to Houston.

Scale Data     Drawings, photos, dimensions, and descriptions of a prototype 
	       (q.v.) rocket used in making a model of that rocket.

Scale Plan     Instructions, diagrams, and patterns for building a model of 
	       a prototype (q.v.) rocket.  A scale plan specifies details 
	       of a model that may not have anything to do with the prototype, 
	       including materials, scale factor, internal construction, and 
	       compromises in accuracy necessary for safe flight or ease of 
	       construction. See also "Scale Data"

Sectional      A projectile's mass divided by the square of its diameter. Used 
Density        as a measure of a round projectile's ability to coast. See also 
               "Ballistic Coefficient"
 
Shred          A model which has lost one or more fins due to aero loads 
 	       and/or acceleration.  Also used to refer to a model which has 
	       completely come apart during takeoff. Can be used as either a
	       verb or noun. See also "Strip"
 
Silver         A black powder motor, made by Rocketflite, Inc., which produces 
Streak(tm)     a large plume of sparkling exhaust when ignited.  

Single Base    A solid propellant based on a single monopropellant. In 
Propellant     practice usually nitrocellulose in a mixture with stabilizers 
	       and plasticizers. Single base propellants are used as smokeless 
	       powders in ammunition. In rockets, such propellants have been 
	       largely replaced by composites. Single base propellants are not 
	       used in hobby rocketry. See also "Composite Propellant"

SNI            Slimy NAR Insider. A person who associates with (either profes-
	       sionally or casually) members of the NAR board of trustees, 
	       thus being privy to the "inner workings" of the organization. 
	       Said to have originated during "flame wars" on the CompuServe 
	       Sport Rocketry SIG.

SNP            Slimy NAR Politician. Coined by NAR President Mark "Bunny" 
	       Bundick, it refers to an SNI (q.v.) who actually manages to get
	       elected to the NAR board.

Solar          Estes Industries brand of Igniter.  Made from two wire 
Igniter(tm)    conductors with a piece of Nichrome wire connecting them at 
	       one end.  The nichrome wire tip of the igniter is dipped in 
	       a pyrogenic compound which flares to ignite the rocket motor. 

Spill Hole     An opening cut in the top of a parachute to increase the 
	       sink rate (thus decrease drift distance) and aid recovery 
	       on windy days.

Sport          The journal of the National Association of Rocketry. 
Rocketry       Previously known as *American Spacemodeling* (q.v.). Published 
               six times per year. Distributed as part of membership to 
               all active NAR members but also available off the rack in 
               larger hobby shops. It has no connection with the CompuServe
	       discussion group of the same name. Current editor: Steve Weaver.

Squib          A small explosive device used to detonate larger explosive 
	       charges. While the term is sometimes used to describe igniters 
	       used in hobby rocketry, especially HPR igniters such as electric 
	       matches (q.v.), true squibs are almost *never* used as igniters 
	       since their purpose is to set up a detonation pressure wave to 
	       set off pressure sensitive explosives (e.g. plastic explosive), 
	       while an igniter must start a (relatively) low speed flame front 
	       so that the motor burns, rather than explodes.

String Test    A simple method for testing the stability of a model.  A string 
               approximately 10ft long is tied to the center of gravity of a
	       fully prepped rocket which is then twirled overhead in a circle. 
	       If the nose points in the direction of the spin and the rocket 
	       does not wobble then it is very likely a stable design.  
	       
	       The string test is not very reliable IMHO since it introduces 
	       another component, namely radial acceleration, that is completely
	       absent in normal flight. When you tie the string to the rocket 
	       at the CG, it's not really at the CG but attached to the outer 
	       surface of the body tube *above* the CG (which is actually inside
	       along the center of the tube). In order for the rocket not to 
	       twirl, the projection of the string has to pass through the CG. 
	       This is fine as long as the rocket is moving in a linear fashion.
	       But when you start swinging it, it's no longer moving linearly, 
	       but being constrained to a circle. This forces the rocket (if 
	       it's stable) to assume an angle of attack in order to keep 
	       pointing into the "relative wind". This angle means that the 
	       projection of the string no longer passes through the CG, but 
	       slightly behind it. You have to move the string slightly forward 
	       for the string to point through the CG while you swing it.

Strip          Terms describing a parachute that has had one or more shroud
Stripped       lines pull free due to opening shock. Usual cause is recovery
	       deployment at too high a speed, but can also be due to age (of
	       the tape disks on a plastic chute) or poor construction. Can
	       be used as a verb or noun. See also "Shred" and "Reef"

Suction Lock   The Mother of all Base Drag. See "Bernoulli Lock"

SuperRoc       An NAR competition based on high aspect ratio (i.e. large
	       length-to-diameter) rockets. The length of the rocket is
	       dependent on its motor size with the smallest (1/4A) having a 
	       minimum length of 25cm. The minimum length goes up 25cm for 
	       each motor class (e.g. 1/2A is 50cm, "A" is 75cm, etc.) so that 
	       a "G" SuperRoc must be at least 225cm long. Maximum length is 
	       twice the minimum and the scores are weighted in favor of longer 
	       rockets. In case your calculator needs recharging, this means 
	       that a "G" SuperRoc could be nearly 14 ft long!

	       Like many types of contests, SuperRoc has no real "point" other
	       than to create a competition that is difficult to do. Some
	       sanitized versions of SuperRocs have been put out as kits,
	       such as the Estes "Mean Machine" (a D class SR) and the MRC
	       "Big Ben" (a "B" or "C" class SR).

Terminal       In the powered phase, the speed where the motor thrust equals 
Velocity       the combined forces of gravity and aero drag. Theoretically, the 
	       rocket would continue ascending at a constant speed (i.e. no 
	       acceleration) with these forces in balance. This doesn't actually
	       happen since motor thrust varies with time and aero drag with 
	       altitude. A second meaning is, when descending, where aero drag 
	       balances the weight of the descending model. If under a 'chute 
	       or other high drag recovery aid, this is quite slow. If in core
	       sample (q.v.) mode this speed can be several hundred feet/sec.
	       See also "Hyperterminal Velocity"

Thermalite     A material, originally used to detonate plastic explosive, which 
	       burns at a controlled rate and high temperature. Used with rocket
	       motors as an ignition enhancement. It can be ignited by electric 
	       (nichrome) means, flash bulbs or the exhaust of a previously 
	       started motor. It comes in three burning speeds color coded as 
	       pink (slow), green (medium) and white (fast). For a rough order 
	       of magnitude, slow is around 1/2 in/sec and fast is 2 1/2 in/sec 
	       in free air, but this can be affected by temperature, humidity, 
	       pressure and whether or not the fuse is sheathed in a tube.

Tiger Tail(tm) An igniter sold by Quest Aerospace consisting of two very 
	       thin copper foil leads separated by and even thinner plastic 
	       insulator with the pyrogenic compound at the tip. Essentially
	       a mini Copperhead (q.v.), its name comes from the orange and
	       black striped tape strip provided to allow it to be used with
	       ordinary alligator clip ignition systems.

Time Delay     See "Delay Train"

Triple Base    A solid propellant based on three monopropellants and additives.
Propellant     In practice, the monopropellants are usually nitroglycerin,
	       nitrocellulose, and nitroguanidine. In military rockets, 
	       such propellants have been largely replaced by composites. 
	       Triple base propellants are not used in hobby rocketry. See 
	       also "Composite Propellant"

Tripoli        Tripoli Rocketry Association.  A consumer rocketry organization
(TRA)          founded to promote the interests of high power and advanced 
               rocketry enthusiasts.  

Tripolitan     *The Tripolitan...America's High Power Rocketry Magazine*
               The bimonthly journal of the Tripoli Rocketry Association,
               published until July/August 1992. It became *HPR Magazine*
	       (q.v.) with the Sept/Oct 1992 issue).

Through The    An HPR fin attachment technique which provides much greater 
Wall (TTW)     strength than the typical surface mount used in model rocketry. 
 	       To use TTW, slots are cut in the body tube where the fins mount 
	       and the fins are built with extended tabs on the root edge which 
	       fit through these slots. In one form of TTW, the tabs are 
	       short and just provide a surface to build up epoxy fillets on 
	       the inside as well as the outside. In a stronger version of TTW, 
	       the tabs reach all the way to the motor tube where they are 
	       glued forming a very rigid box structure (also known as TTW-GTMT
	       for "Glued To the Motor Tube).

Wadding        Any flame retardant material used to prevent the scorching of 
	       the recovery system do to the heat of the ejection charge.  
	       The material (usually a boron treated paper tissue) is placed 
	       in the body tube between the engine and the recovery system.
	       See also "Ejection Baffle"

Waiver         The term used to describe the official permission given by 
	       the FAA allowing rockets with more than 113 grams of fuel or 
	       weighing more than 1 pound to be flown into FAA controlled 
	       airspace.  See also "FAR 101"

Woosh          The humorous, genderless, politically correct way to refer to 
Generator      the propulsion device in a hobby rocket; thus avoiding the
(w.g.)         great motor/engine debate (see discussion at the end).

YABAR          Yet Another Born Again Rocketeer.

Zipper         A devastating side effect of mounting the shock cord to the motor
Effect         mount (which is often done for strength or to anchor a piston 
	       ejection system). If strong and thin cord is used (e.g. Kevlar) 
	       and the recovery system opens at too high a speed and/or the 
	       piston comes all the way out of the body, then the line can "zip"
	       open the body tube all the way down to the motor mount :-(   A 
	       sufficiently strong top mounted shock cord can partially zip a 
	       body tube if opened at a high enough speed.

--------------------------------

And the final burning question: Is the proper term rocket 'engine' or rocket 
'motor'? Some thoughts from Buzz McDermott:

    I don't know.  I don't really care.  And neither should you!  In this 
    hobby 'motor' and 'engine' are taken to mean the same thing and both
    refer to "the thing in the rocket which makes it go 'whoosh!!' (or 'roar',
    if flying high power :-)".  If you want a sure way to start a fight with 
    a fellow rocketeer, just argue that whatever term he/she uses is the wrong 
    one!

While I think Buzz's response reflects the correct attitude to the question, 
the subject comes up often enough that a real definition is required. The 
difficulty comes since there are several "real" interpretations of the terms 
involved. The following discussion is intended for the purposes of education 
only to clear up some of the rampant misunderstandings seen periodically. It 
should not be used to start flame wars :-) I think that by the end, you'll see 
that the subject is complicated enough that *either* term is perfectly 
acceptable. And, no, I'm not weaseling out on this one.

>From a mechanical engineering standpoint, "motor" is the more general term. 
It is defined as anything that imparts mechanical motion (hence the name). 
"Engine" is more specific and despite its Roman origins (where it meant 
mechanical weapons of war and "Engineer" was a military rank) the commonly 
accepted definition today is "A device which creates mechanical force (rotary 
or linear) by means of a mechanism converting stored chemical energy through a 
thermal process." In other words, a heat engine. Look up Carnot.

Thus we have internal combustion engines (gasoline, diesel, etc) which do 
the thermal conversion right in the mechanism itself; external combustion 
engines (steam, Stirling, etc) where the thermal conversion takes place 
outside the mechanism and the heat is transferred by a working fluid; and 
continuous combustion engines (gas turbines) where the various cycle phases 
(mixing, compression, combustion and expansion) are separated by distance 
along the engine rather than by time.

Electric motors are called such because even though they do an energy conversion
by means of a mechanism and have a mechanical (rotary or linear) output, there 
is no consumption of fuel and no thermal component to the conversion.

Jets and rockets get into a gray area, though. Turbojets, such as used on 
airliners, helicopters, etc., are clearly engines. While they don't use a 
mechanical device for the thermal expansion (e.g. a piston) they do have 
mechanical compressors and power take-offs in major support roles. However, it 
is possible to make a jet with no moving parts, e.g. a ram jet. 

Likewise, the "whoosh generators" we use in the hobby are clearly motors. While 
they do consume a chemical fuel and produce thrust by a thermal conversion, 
there is no mechanism, no moving parts at all except the exhaust itself. Liquid
fueled rocket "engines" are less clear.  True they have propellant pumps, valves
and lots of other moving bits, but their support roles are much less central 
than the compressors on a turbojet. You can build a liquid fueled rocket without
pumps at all, as Goddard and many amateurs have shown (see "Hyper for Hypergols"
in the Jul/Aug 93 HPRM for an example). This limits you to comparatively low 
propellant flow rates, however, and pumps are used to enhance the process. 
Generally, the sheer volume and complexity of the mechanism on a modern rocket 
(e.g. a Titan or the Space Shuttle) award it the term "engine."

The above discussion, though, is rooted in the past. In our modern, information
society we have "compute engines" and "graphics engines" to reflect the 
expanded role these devices play in our daily lives. Accordingly, the term 
"engine" has been broadened considerably and a current definition is "a device
to effect a desired outcome" which pretty much covers everything. From this
point of view, "engine" is the superior of the term "motor." If you consider
that the "desired outcome" of flying our rockets is to put them high in the
air then a "rocket engine" is the device to effect it.

I think that you should find enough information here to defend either position!





