Glossary
Velocity Manual Definitions
5 Minute Epoxy - this is supplied in the kit and is used for quick bonding to hold parts in position for permanent lay-ups. It will not dissolve the blue foam.
Aero-Poxy- This is a one - one mix Structural Adhesive. Used in the kit for bonding
premade parts together and bonding in Metal parts. Structural Adhesive usually
needs to be thickened with a filler like Cabosil.
BID - 8.9 Ounce Bi-Directional referred to as BID in the manual. BID has strength fibers that run in two directions. BID is a coarse woven cloth used by the builder throughout to attach mating parts as well as constructing wing, rudder, and aileron end ribs. See also Hexcel BID.
BiDirectional Cloth - See BID.
Bondo - a fast hardening putty that can be bought at any auto supply or hardware store. It is used to hold parts in place while applying permanent glass lay-ups. Do not use on blue foam because it will dissolve the foam.
Cabosil - Sometimes just referred to as "Cabo". Cab-O-Sil is a thickening agent for resin or structural adhesive . We found that by adding Cab-O-Sil to VelociPoxy or EZ-Poxy, we formed a strong, solid, heavy, but nonporous filler. When mixed with VelociPoxy to a paste consistency, it is good for fixing chipped or damaged edges of cowlings, doors, etc. We also found it to be very helpful in filling the porous surfaces left after the Micro-Balloon process has been sanded. Apply with a putty knife or squeegee to porous surfaces. A small amount of Cab-O-Sil may be added to Micro-Balloon to make the mixture stickier, so that it stays where up put it. This is especially helpful on vertical or upside down lay-ups. Be careful to remove all excess Cab-O-Sil, because once it has cured, it is very difficult to sand. Following cure, sand with 120-180 grit paper, then prime with epoxy primer. You will find that all those annoying pin holes have disappeared.
Carbon Fiber - Carbon is used in the Elite models for fuselage stiffening (door beams) and in the RG for main gear reinforcement. There are no Kevlar or hybrid fabrics used in the Velocity aircraft. It is also sometimes used in the aileron pockets, portions of the cowling.
Divinycell - (Blue P.V.C.) used extensively in the factory in the molding process of the Velocity aircraft. The builder uses it in the fabrication of the rear bulkhead and strake baffles and bulkheads.
E-glass - (Electrical) the standard of the industry, both for marine and general aviation use. It is used throughout the construction. Fiberglass is usually named for the orientation of the strength fibers in it and the weight of the cloth.
EZ-Poxy - is used in all major lay-ups on foam and all lay-ups of glass to glass. EZ-Poxy
hardener is mixed with DER 324 resin at a 44:100 ratio. For lay-ups on foam, a
slurry of EZ-Poxy and micro balloons is used. Throughout the construction manual
this mixture is referred to as Micro-Slurry. It is also used with milled fiber for
structural fillets and structural bonding such as hinge pockets for the speed brake,
doors, etc. This epoxy was known as Epolite (2180/2183/2184) and SafetyPoxy
in past manuals.
Flox - Flocked cotton fiber which may be used as a structural filler interchangeably with the milled fiber described above. Flox is not as dense or heavy as milled fiber.
Foam - See Polystyrene and Dyvinylcell.
Glass Bubbles - These are microscopic glass bubbles that the builder adds to resin to form a slurry for filling voids, forming fillets under glass lay-ups, and joining foam to foam and glass to foam. Mixed with EZ-Poxy, the bubbles lighten the lay-up and provide resistance to elamination. It is used with all foam lay-ups. The EZPoxy slurry is called Micro-Slurry in the manual. A dryer and thicker form of Micro-Slurry is called Micro-Balloon. Many people have been confused by statements to use EZ-Poxy Micro-Slurry to cover the blue polystyrene foam surfaces just prior to glassing, since we also state in the plans that EZ-Poxy will dissolve the blue foam, but the slurry mix will not harm the blue foam. The epoxy has been sufficiently diluted by the filler material so do not be apprehensive about using the EZ-Poxy slurry on the core surfaces.
Hexcel BID - Hexcel 17 Ounce Biaxial Cloth is used by Velocity in premolded parts only such as the fuselage outer skin and landing gear reinforcement for torsional loading. Hexcel 12 Ounce Biaxial Cloth - used by Velocity in premolded parts only such as the inner fuselage and strake skins and other small parts like the spinner, wheel pants, sump tank, etc.
Hot Glue - useful for holding parts in place, faster and cleaner than Bondo. It holds foam very well.
Jeffco - Jeffco 9700, a thick two-part grey epoxy with excellent fuel properties that coats very evenly, and can be used to seal the Velocity's strakes completely in just two coats. Note that there are two hardeners, slow and fast. Trust me, you want the slow hardener. Ask me how I know sometime.
Knytex Bid - Knytex 17 Ounce Biaxial Cloth - used by Velocity for primary shear web construction in all spars to handle compression loading. Knytex 12 Ounce Biaxial Cloth - used by Velocity in secondary shear web construction.
Marine Grade Plywood - The wood supplied with the Velocity kit is a superior grade 6 mil, 5 ply plywood . It is specially designed and manufactured for epoxy lamination in the marine industry. It is superior to aircraft birch when used with epoxy for lamination of wood to glass as used in the Velocity construction process.
Micro-Slurry - For lay-ups on foam, a slurry of EZ-Poxy and micro balloons is used, and is called micro-slurry, or just micro or "schmooey"
Milled Fiber - finely chopped glass fiber that the builder adds to resin to form a slurry to fill voids at hard points, attach glass to metal, and other structural glass to glass construction. It is light green in color, and much denser than the glass bubbles. Milled fiber is used for installing hard points, structural fillets and fairings, etc. It has superior secondary adhesive qualities. Mix with EZ-Poxy for filling voids around structural glass to glass lay-ups for compatibility with the EZ-Poxy layups. Use with Structural Adhesive to attach metal pieces. Resin and Milled Fiber slurry is called Micro-Glass in the manual.
Polystyrene Foam - this blue foam is a premium grade of extruded, not expanded, foam. All the foam parts have been pre-cut by Velocity with a hot wire to form the airfoils in the wings, winglets, and elevators.
Plywood - See Marine Grade Plywood.
Roving - Certanteed 22 Ounce Woven Roving - used only by Velocity in the cowling reinforcement.
Schmooey - see Microslurry.
S-Glass - a structural fiber, strong in tension, used in the spar caps and gear legs at the factory.
Structural - This is a two-part structural Adhesive, see Aeropoxy.
Triax - Knytex 20 Ounce Triaxial is called TRIAX in the construction manual, is used throughout. TRIAX has strength fibers running in three directions with one of them being the Major Axis. The Major Axis is shown by a line on the cloth. The builder will use it for bulkhead reinforcement, the skin of the wings and canard, and fabrication of various hard points and energy absorbing pads.
Traxial cloth - see Triax.
UNI - Hexcel 7.2 Ounce Unidirectional called UNI in the manual. UNI has strength fibers running in one direction. UNI is used at the factory in the molding of the outer fuselage skin. It is used by the builder in the winglets, winglet attachment, elevators
and canard skin.
UniDirectional Cloth - See Uni.
VelociPoxy - these systems are used primarily in the finishing and filling , never for glass lay-ups. VelociPoxy hardener is mixed with DER 324 resin at a 1:2 ratio. For finish work, VelociPoxy is mixed with micro-balloon to create a smooth easy to sand
General Composite Definitions
ACETONE: Commonly used wipe solvent. Also known as 2-propanone and Di-methylketone. Used for cleaning composite surfaces prior to bonding and also metal surfaces prior to other treatments. Can also be used to remove uncured epoxy resin from tools and other items. Classed as “Seriously Flammable” with a flashpoint of –4 F (-20 C). Has a high evaporation rate. Mat be procured to U.S. Federal Specification O-A-51H or ASTM-D-329. Solvents and Reducers
ADDITIVE: Any substance added to another substance, usually to improve properties, such as plasticizers, initiators, light stabilizers, and flame retardants. See also filler. Fillers
ADHESIVE: A substance capable of holding two materials together by surface attachment. Adhesive can be in film, liquid, or paste form. In this context, the term is used to denote structural adhesives, i.e., those which create attachments capable of transmitting significant structural loads. Adhesives
ARAMID: A type of highly oriented organic material derived from polyamide (nylon) but incorporating aromatic ring structure. Used primarily as a high-strength, high-modulus fiber. Kevlar and Nomex are examples of aramids. Aramid and Carbon Fiber
BAGGING: Applying an impermeable layer of film over an uncured part and sealing edges so that a vacuum can be drawn. Vacuum Bagging
BIAS FABRIC: Warp and fill fibers at an angle to the length of the fabric. Knitted Fabric
BLISTER: Debond of paint or other coating from part surface. Undesirable rounded elevation of the surface of a plastic with boundaries that are more or less sharply defined, resembling in shape to a blister on the human skin. The blister may burst and become flattened.
BREATHER (BREATHER CLOTH): A loosely woven material such as glass fabric that will serve as a continuous vacuum path over a part or the repair area, but is not in direct contact with the part or the repair area. Vacuum Bagging
CARBON FIBER: Fiber produced by the pyrolysis of organic precursor fibers, such as rayon, polyacrylonitrile (PAN), and pitch in an inert environment. The term is often used interchangeably awith the term graphite; however, carbon fibers and graphite fibers differ. The basic differences lie in the temperature at which the fibers are made and heat treated, and in the amount of elemental carbon produced. Carbon fibers typically are carbonized in the region of 1315 C (2400 F) and assay at 93 to 95% carbon, while graphite fibers are graphitized at 1900 to 2480 C (3450 to 4500 F) and assay at more than 99% elemental carbon.
CAST: To form material into a certain shape by pouring it into a mold and letting it harden without applying external pressure. Mold Making
CASTING RESIN: A resin in liquid form that can be poured or otherwise introduced into a mold and shaped without pressure into solid articles. Polyester Resin
CATALYST: A substance that changes the rate of a chemical reaction without itself undergoing permanent change in composition or becoming a part of the molecular structure of the product. A substance than markedly speeds up the cure of a compound when added to minor quantity as compared to the amounts of primary reactants. Solvents and Reducers
CHOPPED STRAND MAT: A mat formed of strands cut to a short length, randomly distributed, without intentional orientation, and held together by a binder.
CHROME FINISH (VOLAN ‘A’): Applied to glass fibers to give good bonding to polyester and epoxy resins.
COMPOSITE MATERIAL: A combination of two or more materials (reinforcing elements, fillers, and composite matrix binder), differing in form or composition on a macro scale. The constituents retain their identities; that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another.
COMPOUND: The intimate admixture of a polymer with other ingredients, such as fillers, softeners, plasticizers, reinforcement, catalysts, pigments, or dyes. A thermoset compound usually contains all the ingredients necessary for the finishe dproduct, while a thermoplastic compound may require subsequent addition of pigments, blowing agents, etc.
CORE: (A) The central member, usually foam or honeycomb, of a sandwich construction to which the faces of the sandwich are attached or bonded. (B) The central member of a plywood assembly. (C) A channel in a mold for circulation of heat transfer media (D) Part of a complex mold that forms undercut parts. (E) A device on which prepreg is wound.
CORROSION: The deterioration of a metal by chemical or electrochemical raction resulting from exposure to weathering, moisture, chemicals, or other agents or media.
CURING AGENT: A catalytic or reactive agent that, when added to a resin, causes polymerization. Also called hardener.
DELAMINATION: Separation of the layers of material in a laminate, either local or covering a wide area. Can occur in the cure or subsequent life.
E-GLASS: A family of glasses with a calcium aluminoborosilicate composition and a maximum alkali content of 2.0%. A general purpose fiber that is most often used in reinforced plastics and is suitable for electrical laminates because of its high resistivity.
EPOXY RESIN: A polymerizable thermoset polymer containing one or more epoxide groups and curable by reaction with amines, alcohols, phenols, carboxylic acids, acid anhydrides, and mercaptans. An important matrix resin in composites and structural adhesives. Epoxy Resin
FIBER CONTENT: The amount of fiber present in a composite. This is usually expressed as a percentage volume fraction or weight fraction of the composite.
FIBER COUNT: The number of fibers per unit width of ply present in a specified section of a composite.
FIBERGLASS REINFORCEMENT: Material used to reinforce a resin matrix using continuous or discontinuous glass fibers. Available as mat, roving, fabric, etc. It is incorporated into both thermosets and thermoplastics.
FIBER-REINFORCED PLASTIC (FRP): A general term for a composite that consists of a resin reinforced with cloth, tape, mat, or strands of any fiber form and using any type fiber.
FILL: Yarn oriented at right angles to the warp in a woven fabric. Also called “weft” or “woof”.
FILLER: A relatively inert substance added to a material to alter its physical, mechanical, thermal, electrical, and other properties, or to lower coast or density. Fillers Fillers
FLAME RETARDED RESIN: A resin compounded with certain chemicals to reduce or eliminate its tendency to burn. Polyester Resin
GEL COAT: A quick setting resin applied to the surface of a mold and gelled before lay-up. The gel coat becomes an integral part of the finished laminate, and is usually used to improve surface appearance and bonding. Gelcoats
HAND LAY-UP: The process of placing (and working) successive plies of reinforcing material or resin-impregnated reinforcement in position on a mold by hand.
HARDENER: A substance or mixture added to a plastic composition to promote or control the curing action by taking part in it. The term is also used to designate a substance added to control the degree of hardness of the cured film.
IMPREGNATE: In reinforced plastics, to saturate the reinforcement with a resin.
KNITTED FABRICS: Fabrics produced by interlooping chains of yarn. Knitted Fabric
LAMINATE (noun): A product made by bonding together two or more layers (plies) of material.
LAY-UP: (A) The reinforcing material placed in position in the mold. (B) The process of placing the reinforcing material in position in the mold. (C) The resin-impregnated reinforcement.
MEKP: Methyl ethyl ketone peroxide, a catalyst for polyester resins. Highly corrosive. Solvents and Reducers
MICROSPHERES: Small, hollow glass spheres used as fillers n epoxy and polyester compounds to reduce density. Fillers
MILLED FIBER: Continuous glass strands hammer milled into very short glass fibers. Useful as inexpensive filler or anticrazing reinforcing fillers for adhesives. Fillers
MOLD: The cavity or matrix into or on which the plastic composition is placed and from which it takes form. To shape plastic parts of finished articles by heat and pressure. The assembly of all the parts that function collectively in the molding process.
MOLDING: The forming of a polymer or composite into a solid mass of prescribed shape and size by the application of pressure and heat for given times. Sometimes used to denote the finished part.
MOLD-RELEASE AGENT: A lubricant, liquid, or powder (often silicone oils and waxes), used to prevent sticking of molded articles in the cavity. Mold Release
MOLD SURFACE: The side of a laminate that faced the mold (tool) during cure, often called the tooled surface.
PEEL PLY: A layer of open-weave material, usually fiberglass, polyester, or heat-set nylon, applied directly to the surface of a prepreg lay-up. The peel ply is removed from the cured laminate immediately before bonding operations, leaving a clean resin-rich surface that may need no further preparation for bonding, other than application of a primer where one is required. Vacuum Bagging
PLAIN WEAVE: A weaving pattern in which the warp and fill fibers alternate, that is, the repeat pattern is warp/fill/warp/fill, etc. Both faces of a plain weave are identical.
POLYMER: A large molecule created by a large number of smaller molecules, called monomers, in a regular pattern.
POT LIFE: The length of time, at some specified temperature, that a catalyzed resin is workable. Also known as working life.
PRIMER: A coating applied to a surface, before the application of an adhesive, lacquer, enamel, etc., to improve the adhesion performance or load carrying ability of the bond. Some primers contain a corrosion inhibitor.
REINFORCEMENT: A strong material bonded into a matrix to improve its mechanical properties. Reinforcements are usually long fibers, chopped fibers, etc. A material used to reinforce, strengthen or give dimensional stability to a part.
RELEASE AGENT: A material that is applied in a thin film to the surface of a mold to keep the resin from bonding to the mold. Also called parting agent. Mold Release
RELEASE FILM: An impermeable layer of film that does not bond to the resin being cured. Mold Release
RESIN: In reinforced plastics, the material used to bind together the reinforcement material; the matrix. Most resins are polymers.
RESIN TRANSFER MOLDING (RTM): A process whereby catalyzed thermosetting rein is transferred or injected into an enclosed mold in which the fiber reinforcement has been placed. Cure is normally accomplished without external heat. RTM combines relatively low tooling and equipment costs with the ability to mold large structural parts. In general, thermoplastics are too viscous to be used in RTM even if heat is applied.
ROOM-TEMPERATURE VULCANIZING (RTV): Vulcanization or curing at room temperature by chemical reaction; usually applies to silicones and other rubbers.
ROVING: A number of yarns, strands, tows, or ends collected into a parallel bundle with little or no twist. This term is applied most commonly to glass and Kevlar. Roving
SANDWICH CONSTRUCTIONS: Panels composed of a lightweight core material, such as honeycomb, foamed plastic, etc., to which two relatively thin, dense, high-strength or high-stiffness faces or skins are adhered.
SATIN WEAVE: Weaving pattern producing a satin appearance. “Eight-harness” means the warp yarn crosses over seven fill yarns and under the eighth (repeatedly). Also produced as four harness and five harness.
SELVAGE: The woven-edge portion of a fabric parallel to the warp, finished off so as to prevent the yarns from unraveling.
SOLVENT: A substance (usually a liquid) used for dissolving and/or cleaning materials during reinforced plastics operations. Often flammable or toxic. Should be handled in accordance with safety instructions. Solvents and Reducers
STRUCTURAL ADHESIVE: Adhesives used for transferring required loads between adherends exposed to service environments typical for the structure involved.
SUBSTRATE: A material upon the surface of which as adhesive or resin is spread for any purpose such as bonding or coating.
TACK-FREE: A condition in which a plastic material can be dented with an inert object without sticking to it. It is indicative of a definite stage of hardening.
THIXOTROPIC: Concerning materials that are gel-like at rest, but fluid when agitated. Having high static shear strength at the same time. To lose viscosity under stress.
THREAD COUNT: The number of yarns (threads) per inch or centimeter in either the lengthwise (warp) or crosswise (fill or weft) direction of woven fabrics.
TOOLING: The molds and fixtures used to produce a composite article. Tooling may be made of any suitable material, including composites.
TWO-COMPONENT ADHESIVE: an adhesive supplied in two parts that are mixed before application. Such adhesives usually cure at room temperature. Adhesives
UNIDIRECTIONAL: All of the fibers are oriented in the same direction.
VACUUM BAG MOLDING: A process in which a sheet of flexible transparent material plus bleeder cloth and release film are placed under the layup on the mold and sealed at the edges. A vacuum is applied between the sheet and the lay-up. The entrapped air is mechanically worked out of the lay-up and removed by the vacuum, and the part is cured with temperature, pressure, and time. Vacuum Bagging
VINYL ESTERS: A class of thermosetting resins containing esters of acrylic and/or methacrylic acids, many of which have been made from epoxy resin. Cure is accomplished as with unsaturated polyesters by copolymerization with other vinyl monomers, such as styrene. Vinylester Resin
VULCANIZATION: A chemical reaction in which a rubber is cured by reaction with sulfur or other suitable agents.
WARP: The yarn running lengthwise in a woven fabric. A group of yarns in long lengths and approximately parallel. Fabrics are tensional in the warp direction during weaving. The weft is not tensioned.
WEATHERING: Exposure of plastics to the outdoor environment.
WEAVE: The particular manner in which a fabric is formed by interlacing yarns. Usually assigned a style number.
WEFT: The transverse threads or fibers in a woven fabric. Those fibers running perpendicular to the warp. Also called fill, filling yarn or woof.
WET LAY-UP: A method of making or repairing a reinforced product by applying the resin system as a liquid when the reinforcement is put in place.
WET-OUT: The condition of an impregnated roving or yarn in which substantially all voids between the sized strands and filaments are filled with resin.
WORKING LIFE: The period of time during which a liquid resin or adhesive, after mixing with catalyst, solvent, or other compounding ingredients, remains usable. Also called pot life.
WOVEN ROVING: A heavy glass fiber fabric made by weaving rovig or yarn bundles. Roving
