Misplaced Pages

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76-474: Zenith Aircraft Company is a designer, developer and manufacturer of kit aircraft . The independent, privately owned company was formed in 1992 in Mexico, Missouri , and is based in 20,000+ sq. ft. production facilities at Mexico Memorial Airport . Zenith Aircraft Company has acquired the rights to manufacture and market Zenair kit aircraft designs from designer Chris Heintz of Zenair Ltd . His son Sebastian

152-413: A composite material . The sheets of wood are stacked such that each layer has its grain set typically (see below) perpendicular to its adjacent layers. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces thickness swelling and shrinkage, providing improved dimensional stability; and it makes

228-428: A caveat along the lines of "not suitable for boat In India,marine ply is popularly called "Kitply" after the brand which popularised the concept of water proof marine plywood in the 1980"s. Other types of plywoods include fire-retardant, moisture-resistant, wire mesh, sign-grade, and pressure-treated. However, the plywood may be treated with various chemicals to improve the plywood's fireproofing. Each of these products

304-620: A completed airframe, was the Baby Ace in the late 1920s. Homebuilt aircraft gained in popularity in the U.S. in 1924 with the start of the National Air Races , held in Dayton , Ohio . These races required aircraft with useful loads of 150 lb (68 kg) and engines of 80 cubic inches or less and as a consequence of the class limitations most were amateur-built. The years after Charles Lindbergh 's transatlantic flight brought

380-453: A four-place kit with cabin pressurization and a turboprop engine , cruising at 24,000 feet (7,300 m) and 370 knots (425 mph, 685 km/h). Although aircraft such as this are considered "home-built" for legal reasons, they are typically built in the factory with the assistance of the buyer. This allows the company which sells the kit to avoid the long and expensive process of certification, because they remain owner-built according to

456-642: A fuselage made of birch plywood sandwiching a balsa core, and using plywood extensively for the wings. Plywood was also used for the hulls in the hard-chine Motor Torpedo Boats (MTB) and Motor Gun Boats (MGB) built by the British Power Boat Company and Vosper 's, American PT boats , and the Higgins landing craft critical to the D-Day landings. The American designers Charles and Ray Eames are known for their plywood-based furniture, as

532-401: A good log, called a peeler, which is generally straighter and larger in diameter than one required for processing into dimensioned lumber by a sawmill . The log is laid horizontally and rotated about its long axis while a long blade is pressed into it, causing a thin layer of wood to peel off (much as a continuous sheet of paper from a roll). An adjustable nosebar, which may be solid or a roller,

608-732: A high tensile strength (usually fiberglass or carbon fiber , or occasionally Kevlar ) combined with a structural plastic (usually epoxy , although vinylester is used in some aircraft). The fabric is saturated with the structural plastic in a liquid form; when the plastic cures and hardens, the part will hold its shape while possessing the strength characteristics of the fabric. The two primary types of composite planes are moulded composite, where major structures like wing skins and fuselage halves are prepared and cured in moulds, and mouldless, where shapes are carved out of foam and then covered with fiberglass or carbon fiber. The advantages of this type of construction include smooth surfaces (without

684-402: A large number of other hardwoods. Flexible plywood is designed for making curved parts, a practice which dates back to the 1850s in furniture making. At 3 ⁄ 8 inch (9.5 mm) thick, mahogany three-ply "wiggle board" or "bendy board" come in 4 by 8 feet (1.2 m × 2.4 m) sheets with a very thin cross-grain central ply and two thicker exterior plies, either long grain on

760-417: A larger market for our airplanes. Emerging markets such as China and India could also boost demand for our products, but entire infrastructures will need to be formed before small players like us could benefit. Homebuilt aircraft can be constructed out of any material that is light and strong enough for flight. Several common construction methods are detailed below. This is the oldest construction, seen in

836-468: A peak of interest between 1929 and 1933. During this period many aircraft designers, builders and pilots were self-taught and the high accident rate brought public condemnation and increasing regulation to amateur building. The resulting federal standards on design, engineering, stress analysis, use of aircraft-quality hardware and testing of aircraft brought an end to amateur building except in some specialized areas, such as racing. In 1946 Goodyear restarted

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912-669: A positive influence on the professionalism of its industry members and on the builders/pilots of its products. With concern over fuel prices, we might see a trend toward lower-powered aircraft intended more for pure sport flying rather than the trend toward cross-country aircraft, which has been the norm over the past 30 years. I would expect that toward the end of that period, there might be some design ventures into electric-powered aircraft, but only if battery technology improves significantly. We might see more motorglider-type homebuilts, tied both to high fuel prices and emerging electric-propulsion technology. What we do at Van's could mirror some of

988-431: A press at a temperature of at least 140 °C (284 °F), and at a pressure of up to 1.9 MPa (280 psi) (but more commonly 1.4 MPa [200 psi]) to form the plywood panel. The panel can then be patched, have minor surface defects such as splits or small knot holes filled, re-sized, sanded or otherwise refinished, depending on the market for which it is intended. Plywood for indoor use generally uses

1064-498: A result, many manufacturers are turning to low formaldehyde-emitting glue systems, denoted by an "E" rating. Plywood produced to "E0" has effectively zero formaldehyde emissions. In addition to the glues being brought to the forefront, the wood resources themselves are becoming the focus of manufacturers, due in part to energy conservation, as well as concern for natural resources. There are several certifications available to manufacturers who participate in these programs. Programme for

1140-519: A single thick layer of wood. Understanding the industrial potential of laminated wood, he invented the rotary lathe . There is little record of the early implementation of the rotary lathe and the subsequent commercialization of plywood as we know it today, but in its 1870 edition, the French dictionary Robert describes the process of rotary lathe veneer manufacturing in its entry Déroulage . One can thus presume that rotary lathe plywood manufacturing

1216-409: Is Finnish Architect Alvar Aalto and his firm Artek , while Phil Bolger has designed a wide range of boats built primarily of plywood. Jack Köper of Cape Town designed the plywood Dabchick sailing dinghy , which as of 2015 is still sailed by large numbers of teenagers. Plywood is often used to create curved surfaces because it can easily bend with the grain. Skateboard ramps often utilize plywood as

1292-423: Is a composite material manufactured from thin layers, or "plies", of wood veneer that have been stacked and glued together. It is an engineered wood from the family of manufactured boards, which include plywood, medium-density fibreboard (MDF), oriented strand board (OSB), and particle board (or chipboard). All plywoods bind resin and wood fibre sheets ( cellulose cells are long, strong and thin) to form

1368-399: Is also a common European size for Baltic birch ply, and aircraft ply. Sizes on specialised plywood for concrete-forming can range from 15 ⁄ 64 to 13 ⁄ 16  in (6 to 21 mm), and a multitude of formats exist, though 15 × 750 × 1,500 mm (.59in × 30 × 59 in) (19/32in × 2 ft-6in × 4 ft-11in)

1444-533: Is designed to fill a need in industry. Baltic Birch plywood is a product of an area around the Baltic Sea. Originally manufactured for European cabinet makers but now popular in the United States as well. It is very stable composed of an inner void-free core of cross-banded birch plys with an exterior grade adhesive. The face veneers are thicker than traditional cabinet grade Plywood production requires

1520-702: Is extremely strong and light. Howard Hughes' H-4 Hercules was constructed of plywood. The plane was built by the Hughes Aircraft Company employing a plywood-and-resin Duramold process. The specialized wood veneer was made by Roddis Manufacturing in Marshfield, Wisconsin . Usually faced with hardwood , including ash , oak , red oak , birch , maple , mahogany , shorea (often called lauan, meranti, or Philippine mahogany, though having no relation to true mahogany), rosewood , teak and

1596-509: Is from 1 ⁄ 8  to 3 inches (3.2–76.2 mm). The sizes of the most commonly used plywood sheets are 4 by 8 feet (1,220 mm × 2,440 mm) which was first used by the Portland Manufacturing Company, who developed modern veneer core plywood for the 1905 Portland World Fair. A common metric size for a sheet of plywood is 1200 × 2400 mm. 5 × 5 feet (1,500 × 1,500 mm)

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1672-573: Is higher in the center of the panel, and at the outer fibres. Within Europe basic plywood can be divided into three main categories: birch plywood (density approx. 680 kg/m ), mixed plywood (density approx. 620 kg/m ) and conifer plywoods (density 460– 520 kg/m ). Different varieties of plywood exist for different applications: Softwood plywood is usually made either of cedar , Douglas fir or spruce , pine , and fir (collectively known as spruce-pine-fir or SPF) or redwood and

1748-456: Is listed as the owner of Zenith Aircraft Company. Kit designs manufactured by the company include the original two-seat STOL CH 701 , a high-wing all-metal short take-off and landing design, the larger STOL CH 801 four-place aircraft, the STOL CH 750 light sport utility kit airplane, and the two-seat CH 650, an all-metal low-wing cruiser. Other than the 801, these designs may be built to meet

1824-506: Is made of mixed hardwood species of tropical timber . Originally from the Asian region, it is now also manufactured in African and South American countries. Tropical plywood is superior to softwood plywood due to its density, strength, evenness of layers, and high quality. It is usually sold at a premium in many markets if manufactured with high standards. Tropical plywood is widely used in

1900-508: Is made out of wood from dicot trees (oak, beech and mahogany) and used for demanding end uses. Hardwood plywood is characterized by its excellent strength, stiffness, durability and resistance to creep. It has a high planar shear strength and impact resistance, which make it especially suitable for heavy-duty floor and wall structures. Oriented plywood construction has a high wheel-carrying capacity. Hardwood plywood has excellent surface hardness, and damage- and wear-resistance. Tropical plywood

1976-564: Is manufactured to a number of specifications including those outlined since 1931 in the Germanischer Lloyd Rules for Surveying and Testing of Plywood for Aircraft and MIL-P-607, the latter of which calls for shear testing after immersion in boiling water for three hours to verify the adhesive qualities between the plies meets specifications. Aircraft grade plywood is made from three or more plies of birch, as thin as 0.40 millimetres ( 1 ⁄ 64  in) thick in total, and

2052-494: Is not a professional activity. These aircraft may be constructed from "scratch", from plans, or from assembly kits. In the United States , Brazil , Australia , New Zealand and South Africa , homebuilt aircraft may be licensed Experimental under FAA or similar local regulations. With some limitations, the builder(s) of the aircraft must have done it for their own education and recreation rather than for profit. In

2128-579: Is not as good as certified general aviation aircraft. In the United States, in 2003, amateur-built aircraft experienced a rate of 21.6 accidents per 100,000 flight hours; the overall general aviation accident rate for that year was 6.75 per 100,000 flight hours. The accident rate for homebuilt aircraft in the U.S. has long been a concern to the Federal Aviation Administration . At Sun 'n Fun 2010, FAA administrator Randy Babbitt said that homebuilts "account for 10 percent of

2204-539: Is pressed against the log during rotation, to create a "gap" for veneer to pass through between the knife and the nosebar. The nosebar partly compresses the wood as it is peeled; it controls vibration of the peeling knife; and assists in keeping the veneer being peeled to an accurate thickness. In this way the log is peeled into sheets of veneer, which are then cut to the desired oversize dimensions, to allow it to shrink (depending on wood species) when dried. The sheets are then patched, graded, glued together and then baked in

2280-638: Is toward wood-composite aircraft. The basic load carrying material is still wood, but it is combined with foam (for instance, to increase buckling resistance of load carrying plywood skins) and other synthetic materials like fiberglass and carbon fiber (to locally increase the modulus of load carrying structures such as spar caps). Examples of wood-composite designs include: Planes built from metal use similar techniques to more conventional factory-built aircraft. They can be more challenging to build, requiring metal-cutting, metal-shaping, and riveting if building from plans. "Quick-build" kits are available which have

2356-530: Is typically used for construction and industrial purposes. The most common dimension is 1.2 by 2.4 metres (3 ft 11 in × 7 ft 10 in) or the slightly larger imperial dimension of 4 feet × 8 feet. Plies vary in thickness from 1.4 mm to 4.3 mm. The number of plies—which is always odd—depends on the thickness and grade of the sheet. Roofing can use the thinner 16-millimetre ( 5 ⁄ 8  in) plywood. Subfloors are at least 19 millimetres ( 3 ⁄ 4  in) thick,

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2432-438: Is very commonly used. Aircraft plywood is available in thicknesses of 1 ⁄ 8 inch (3 mm) (3-ply construction) and upwards; typically aircraft plywood uses veneers of 0.5 mm (approx 1/64 in) thickness although much thinner veneers such as 0.1 mm are also used in construction of some of the thinner panels. Grading rules differ according to the country of origin. The most popular standards are

2508-454: The FAA 's light-sport aircraft (LSA) definition for operation by Sport Pilots . Zenith Aircraft designs may be built from plans-only (blueprints), selected parts, and from complete kits typically in a few hundred hours. The company holds two-day hands-on workshops at the factory every month to allow potential builders to gain building experience, tour the factory, and go up for a demo flight in

2584-660: The Sun N' Fun Fly-In, which occurs in the early spring in Lakeland, Florida , and the Northwest EAA Fly-In in Arlington, Washington . These events are called fly-ins as many people fly their homebuilts and other aircraft into the airport hosting the show, often camping there for the duration. Both events last a week. Takeoffs and landings at these shows typically number in the thousands. Plywood Plywood

2660-430: The canard design to the homebuilding world and pioneered the use of composite construction. Metal construction in kitplanes was taken to a new level by Richard VanGrunsven in his RV series . As the sophistication of the kits improved, components such as autopilots and more advanced navigation instruments became common. Litigation during the 1970s and 1980s caused stagnation in the small aircraft market, forcing

2736-539: The British Standard (BS) and the American Standard (ASTM). Joyce (1970), however, list some general indication of grading rules: Plywood is used in many applications that need high-quality, high-strength sheet material. Quality in this context means resistance to cracking, breaking, shrinkage, twisting and warping. Exterior glued plywood is suitable for outdoor use, but because moisture affects

2812-538: The Endorsement of Forest Certification (PEFC) Forest Stewardship Council (FSC), Leadership in Energy and Environmental Design (LEED), Sustainable Forestry Initiative (SFI), and Greenguard are all certification programs that ensure that production and construction practices are sustainable. Many of these programs offer tax benefits to both the manufacturer and the end user. The most commonly used thickness range

2888-535: The GA fleet, but 27 percent of accidents. It's not the builders [getting into accidents], but the second owners. We need better transition training." In the US, flight instruction , including primary flight training, can be received in the owner's homebuilt aircraft from any instructor willing to provide such training. A study released in 2012 by the U.S. National Transportation Safety Board concluded that homebuilt aircraft in

2964-629: The National Air Races, including a class for aircraft powered by 200 cubic inch and smaller engines. The midget racer class spread nationally in the U.S. and this led to calls for acceptable standards to allow recreational use of amateur-built aircraft. By the mid-1950s both the U.S. and Canada once again allowed amateur-built aircraft to specified standards and limitations. Homebuilt aircraft are generally small, one to four-seat sportsplanes which employ simple methods of construction. Fabric-covered wood or metal frames and plywood are common in

3040-426: The U.S. have an accident rate 3–4 times higher than the rest of the general aviation fleet. Almost 10% of accidents involving homebuilt aircraft occurred on the craft's first flight. A further 9% of accidents occurred on their first flight after being sold, due to the new owner's unfamiliarity with the craft. The study also identified that powerplant failures and loss of control in-flight accidents were much higher than

3116-513: The U.S., the primary builder can also apply for a repairman's certificate for that airframe. The repairman's certificate allows the holder to perform and sign off on most of the maintenance, repairs, and inspections themselves. Alberto Santos-Dumont was the first to offer for free construction plans, publishing drawings of his Demoiselle in the June 1910 edition of Popular Mechanics. The first aircraft to be offered for sale as plans, rather than

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3192-608: The UK, Japan, United States, Taiwan, Korea, Dubai, and other countries worldwide. It is used for construction purposes in many regions due to its low cost. However, many countries' forests have been over-harvested, including the Philippines, Malaysia and Indonesia, largely due to the demand for plywood production and export. High-strength plywood, also known as aircraft plywood, is made from mahogany, spruce and/or birch using adhesives with an increased resistance to heat and humidity. It

3268-405: The US. Poberezny's Mechanix Illustrated articles gained worldwide acclaim and the concept of aircraft homebuilding took off. Until the late 1950s, builders had mainly kept to wood-and-cloth and steel tube-and-cloth design. Without the regulatory restrictions faced by production aircraft manufacturers, homebuilders introduced innovative designs and construction techniques. Burt Rutan introduced

3344-418: The above thinking. Unfortunately, I don't see the growth potential that there was in the 1980s and 1990s. There seems to be a shrinking pilot base from which to draw people to build kits. Plus, with demographic changes, there is possibly a diminishing interest in, or ability to undertake, aircraft building as a pastime. Hopefully, EAA and AOPA initiatives to interest more people in learning to fly will help create

3420-907: The aircraft structure, but increasingly, fiberglass and other composites as well as full aluminum construction techniques are being used, techniques first pioneered by Hugo Junkers as far back as the late World War I era. Engines are most often the same as, or similar to, the engines used in certified aircraft (such as Lycoming , Continental , Rotax , and Jabiru ). A minority of homebuilts use converted automobile engines, with Volkswagen air-cooled flat-4s , Subaru -based liquid-cooled engines, Mazda Wankel and Chevrolet Corvair six-cylinder engines being most common. The use of automotive engines helps to reduce costs, but many builders prefer dedicated aircraft engines , which are perceived to have better performance and reliability. Other engines that have been used include chainsaw and motorcycle engines. A combination of cost and litigation , especially in

3496-583: The airplane. In February 2014, the company announced that it had shipped 10,000 sets of plans to aircraft builders in over 50 countries. In January 2016, Zenith Aircraft announced that it had purchased the intellectual property including the Sam LS design previously produced by Sam Aircraft , and was planning to produce kits alongside the existing Chris Heintz designs. Homebuilt aircraft Homebuilt aircraft , also known as amateur-built aircraft or kit planes , are constructed by persons for whom this

3572-526: The ancient Greek verb πλέκω . The ancient Egyptians and Greeks cut wood thinly and glued it together in layers with the grain in perpendicular directions as fine wood was in short supply. This is believed to have been done purely for cosmetic and economical purposes but it turned out to be a great alternative to pure wood as it reduced flex, making it a versatile building material. In 1797 Samuel Bentham applied for patents covering several machines to produce veneers. In his patent applications, he described

3648-447: The chance of trapping water in the plywood and hence providing a solid and stable glue bond. It uses an exterior Weather and Boil Proof (WBP) glue similar to most exterior plywoods. Marine plywood can be graded as being compliant with BS 1088 , which is a British Standard for marine plywood and IS:710 is Bureau of Indian Standards (BIS) for marine grade plywood. There are few international standards for grading marine plywood and most of

3724-574: The concept of laminating several layers of veneer with glue to form a thicker piece – the first description of what we now call plywood. Bentham was a British naval engineer with many shipbuilding inventions to his credit. Veneers at the time of Bentham were flat sawn , rift sawn or quarter sawn ; i.e. cut along or across the log manually in different angles to the grain and thus limited in width and length. About fifty years later Immanuel Nobel , father of Alfred Nobel , realized that several thinner layers of wood bonded together would be stronger than

3800-490: The cutting, shaping, and hole-drilling mostly done, requiring only finishing and assembly. Such kits are also available for the other types of aircraft construction, especially composite. There are three main types of metal construction: sheet aluminum , tube aluminum, and welded steel tube. The tube structures are covered in aircraft fabric , much like wooden aircraft. Examples of metal-based amateur aircraft include: Composite material structures are made of cloth with

3876-599: The drag of rivets), the ability to construct compound curves, and the ability to place fiberglass or carbon fiber in optimal positions, orientations, and quantities. Drawbacks include the need to work with chemical products as well as low strength in directions perpendicular to fiber. Composites provide superb strength to their weight. Material stiffness dependent upon direction (as opposed to equal in all directions, as with metals) allows for advanced "elastic tailoring" of composite parts. Examples of amateur craft made of composite materials include: The safety record of homebuilts

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3952-554: The first aircraft and hence the best known. For that reason, amateur-built aircraft associations will have more specialists for this type of craft than other kinds. The most commonly used woods are Sitka spruce and Douglas fir , which offer excellent strength-to-weight ratios. Wooden structural members are joined with adhesive, usually epoxy . Unlike the wood construction techniques used in other applications, virtually all wooden joints in aircraft are simple butt joints , with plywood gussets . Joints are designed to be stronger than

4028-472: The first homebuilt aircraft. In 1928, Henri Mignet published plans for his HM-8 Pou-du-Ciel , as did Pietenpol for his Air Camper . Pietenpol later constructed a factory, and in 1933 began creating and selling partially constructed aircraft kits. In 1936, an association of amateur aviation enthusiasts was created in France. Many types of amateur aircraft began to make an appearance, and in 1938 legislation

4104-412: The form of an alcoholic solution or powder, which, however, did not provide sufficient accuracy of application. Around 1930 a dry process of gluing veneers to plywood with phenolic resin in form of a film has begun to spread in the production of waterproof plywood. A typical plywood panel has face veneers of a higher grade than the core veneers. The principal function of the core layers is to increase

4180-469: The less expensive urea-formaldehyde glue, which has limited water resistance, while outdoor and marine-grade plywood are designed to withstand moisture, and use a water-resistant resorcinol-formaldehyde or phenol-formaldehyde glue to prevent delamination and to retain strength in high humidity . The adhesives used in plywood have become a point of concern. Both urea formaldehyde and phenol formaldehyde are carcinogenic in very high concentrations. As

4256-401: The members. After the structure has been completed, the aircraft is covered in aircraft fabric (usually aircraft-grade polyester ). The advantage of this type of construction is that it does not require complex tools and equipment, instead employing commonplace items such as saw, planer, file, sandpaper, and clamps. Examples of amateur-built wood and fabric designs include: A recent trend

4332-408: The mid-1950s when EAA founder Paul Poberezny wrote a series of articles for the magazine Mechanix Illustrated where he explained how a person could buy a set of plans and build their own aircraft at home. In 1955, Poberezny co-founded, with Robert D. Blacker, EAA's first youth outreach program, Project Schoolflight , which brought "homebuilding" into high school industrial arts classes throughout

4408-476: The mid-1980s era, discouraged general aviation manufacturers from introducing new designs and led to homebuilts outselling factory built aircraft by five to one. The history of amateur-built aircraft can be traced to the beginning of aviation. Even if the Wright brothers , Clément Ader , and their successors had commercial objectives in mind, the first aircraft were constructed by passionate enthusiasts whose goal

4484-461: The original material was not strictly plywood, but a single sheet of veneer. Marine plywood is manufactured from durable face and core veneers, with few defects so it performs longer in both humid and wet conditions and resists delaminating and fungal attack. Its construction is such that it can be used in environments where it is exposed to moisture for long periods. Each wood veneer will be from tropical hardwoods and have negligible core gap, limiting

4560-466: The regulations. One of the terms applied to this concept is commonly referred to as "The 51% Rule", which requires that builders perform the majority of the fabrication and assembly to be issued a Certificate of Airworthiness as an Amateur Built aircraft. A small number of jet kitplanes have been built since the 1970s, including the tiny Bede Aircraft BD-5J . Van's Aircraft and Aircraft Kit Industry Association (AKIA) President Dick VanGrunsven

4636-716: The same rates for certified aircraft. Most nations' aviation regulations require amateur-built aircraft to be physically marked as such (for example in the U.K. "Occupant Warning – This aircraft ... is amateur built." must be displayed ), and extra flight testing is usually required before passengers (who are not pilots themselves) can be carried. The largest airshow in the world is the Experimental Aircraft Association 's annual EAA AirVenture Oshkosh airshow in Oshkosh, Wisconsin , which takes place in late July and early August. Other annual events are

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4712-445: The separation between the outer layers where the bending stresses are highest, thus increasing the panel's resistance to bending . As a result, thicker panels can span greater distances under the same loads. In bending, the maximum stress occurs in the outermost layers, one in tension , the other in compression . Bending stress decreases from the maximum at the face layers to nearly zero at the central layer. Shear stress , by contrast,

4788-548: The sheet, or cross grain. Wiggle board is often glued together in two layers once it is formed into the desired curve, so that the final shape will be stiff and resist movement. Often, decorative wood veneers are added as a surface layer. In the United Kingdom single-ply sheets of veneer were used to make stove pipe hats in Victorian times, so flexible modern plywood is sometimes known there as "hatters ply", although

4864-421: The standards are voluntary. Some marine plywood has a Lloyd's of London stamp that certifies it to be BS 1088 compliant. Some plywood is also labeled based on the wood used to manufacture it. Examples of this are Okoumé or Meranti . In the UK, one can find builders' merchants advertising a grade of ply as "marine ply" that does not conform to BS 1088 - generally online adverts for these products will include

4940-410: The strength of the panel consistent across all directions. There is usually an odd number of plies, so that the sheet is balanced, that is, the surface layers have their grains set parallel to one another. This balance reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it has high stiffness perpendicular to the grain direction of

5016-501: The strength of wood, optimal performance is achieved where the moisture content remains relatively low. Subzero conditions do not affect the dimensional or strength properties of plywood, making some special applications possible. Plywood is also used as an engineering material for stressed-skin applications. It has been used for marine and aviation applications since WWII. Most notable is the British de Havilland Mosquito bomber, with

5092-453: The surface ply. Smaller, thinner, and lower-quality plywoods may only have their plies (layers) arranged at right angles to each other. Some better-quality plywood products by design have five plies in steps of 45 degrees (0, 45, 90, 135, and 180 degrees), giving strength in multiple axes. The word ply derives from the French verb plier , "to fold", from the Latin verb plico , from

5168-479: The surviving companies to retain older, proven designs. In recent years, the less restrictive regulations for homebuilts allowed a number of manufacturers to develop new and innovative designs; many can outperform certified production aircraft in their class. An example of high-end homebuilt design is Lancair , which has developed a number of high-performance kits. The most powerful is the Lancair Propjet ,

5244-404: The thickness depending on the distance between floor joists . Plywood for flooring applications is often tongue and groove (T&G); This prevents one board from moving up or down relative to its neighbor, providing a solid-feeling floor when the joints do not lie over joists. T&G plywood is usually found in the 13-to-25-millimetre ( 1 ⁄ 2 to 1 in) range. Hardwood plywood

5320-443: The top smooth surface over bent curves to create transition that can simulate the shapes of ocean waves. Typical end uses of spruce plywood are: There are coating solutions available that mask the prominent grain structure of spruce plywood. For these coated plywoods there are some end uses where reasonable strength is needed but the lightness of spruce is a benefit, e.g.: Phenolic resin film coated (Film Faced) hardwood plywood

5396-825: Was amended to provide for a Certificat de navigabilité restreint d'aéronef ( CNRA , " restricted operating certificate for aircraft "). 1946 saw the birth of the Ultralight Aircraft Association which in 1952 became the Popular Flying Association in the United Kingdom , followed in 1953 by the Experimental Aircraft Association (EAA) in the United States and the Sport Aircraft Association in Australia . The term "homebuilding" became popular in

5472-693: Was an established process in France in the 1860s. Plywood was introduced into the United States in 1865 and industrial production there started shortly after. In 1928, the first standard-sized 4 ft by 8 ft (1.22 m by 2.44 m) plywood sheets were introduced in the United States for use as a general building material. Artists use plywood as a support for easel paintings to replace traditional canvas or cardboard. Ready-made artist boards for oil painting in three-layered plywood (3-ply) were produced and sold in New York as early as 1880. There were experiments with gluing plywood with phenolic resins, mostly in

5548-523: Was asked about the future of the kit aircraft industry in a wide-ranging interview in KitPlanes magazine in December 2012: I don't expect to see dramatic changes in the industry within the next five years. Ten years; who knows – it’s too dependent on fuel prices, FAA policy, etc. Overall, I think our industry will continue to mature, particularly as AKIA is successful in growing and having

5624-490: Was formed in two separate mirror-image halves, using curved moulds. Structural aircraft-grade plywood is most commonly manufactured from African mahogany, spruce or birch veneers that are bonded together in a hot press over hardwood cores of basswood or poplar or from European Birch veneers throughout. Basswood is another type of aviation-grade plywood that is lighter and more flexible than mahogany and birch plywood but has slightly less structural strength. Aviation-grade plywood

5700-594: Was to fly. Aviation took a leap forward with the industrialization that accompanied World War I . In the post-war period, manufacturers needed to find new markets and introduced models designed for tourism. However, these machines were affordable only by the very rich. Many U.S. aircraft designed and registered in the 1920s onward were considered "experimental" by the (then) CAA, the same registration under which modern homebuilts are issued Special Airworthiness Certificates . Many of these were prototypes, but designs such as Bernard Pietenpol 's first 1923 design were some of

5776-439: Was used in the construction of air assault gliders during World War II and also several fighter aircraft , most notably the multi-role British Mosquito . Nicknamed "The Wooden Wonder", plywood was used for the wing surfaces, and also flat sections such as bulkheads and the webs of the wing spars. The fuselage had exceptional rigidity from the bonded ply-balsa-ply 'sandwich' of its monocoque shell; elliptical in cross-section, it

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