below. Wood and fabric This is the oldest construction, seen in 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 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, but commonplace items such as saw, planer, file, sandpaper, and clamps. Examples of amateur-built wood and fabric designs include: The classic Pietenpol Air Camper, a homebuilt that has been built since the 1920s The Bowers Fly Baby, a low-wing monoplane which has been popular since the 1960s The Ison miniMAX Wood/composite mixture A recent trend 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 glass- and carbon fibre (to locally increase the modulus of load carrying structures like spar caps, etc.). Examples of wood-composite designs include: Ibis experimental aircraft project, designed by Roger Junqua KR series of homebuilts designed by Ken Rand PIK-26 designed by Kai Mellen Metal 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 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 aluminium, tube aluminium, and welded steel tube. The tube structures are covered in aircraft fabric, much like wooden aircraft. Examples of metal-based amateur aircraft include: The Murphy Moose, Rebel, Super Rebel and Maverick, produced by Murphy Aircraft The Vans RV-4, RV-8, RV-10 and other models produced by Van's Aircraft, are the most popular metal homebuilt aircraft Chris Heintz's Zenith CH601 Zodiac and Zenith STOL CH701 family of two-seat kit planes The ARV