The Sandlin Goat is an American

parasol wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

, single-seat,

ultralight Ultralight aviation (called microlight aviation in some countries) is the flying of lightweight, 1- or 2-seat fixed-wing aircraft. Some countries differentiate between weight-shift control and conventional three-axis control aircraft with aile ...

glider that was designed by Mike Sandlin and is provided in the form of technical drawings for amateur construction.Bertrand, Noel; Rene Coulon; et al: ''World Directory of Leisure Aviation 2003-04'', page 55. Pagefast Ltd, Lancaster OK, 2003. ISSN 1368-485X

Design and development

The Goat first flew on February 1, 2003. The aircraft was designed as a

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

development of the

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

Bug. Like the Bug it is intended to be an inexpensive and easy-to-fly three-axis-controlled aircraft similar to a

primary glider Primary glider aircraft, gliders are a category of aircraft that enjoyed worldwide popularity during the 1920s and 1930s as people strove for simple and inexpensive ways to learn to fly.Schweizer, Paul A: ''Wings Like Eagles, The Story of Soaring ...

, although the designer terms it an ''airchair''. The Goat has an empty weight of under and so qualifies to be flown under the United States

FAR 103 Ultralight Vehicles Ultralight aircraft exist outside of the United States. In most countries, ultralights are a class of aircraft. A completely different legal concept is valid within the USA. The FAA makes explicitly clear that ultralight vehicles are not air ...

regulations and does not require registration or a pilot license. The aircraft is made available as technical drawings, not plans, to allow potential builders to study them. Sandlin makes his

computer assisted design Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve c ...

drawings available free of charge as downloads in .dxf, .dwf and .gif formats and has explicitly released them to the

public domain The public domain (PD) consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly Waiver, waived, or may be inapplicable. Because no one holds ...

. The Goat 1 drawings consist of 71 sheets. The designer considers his aviation activities a hobby only. The aircraft is predominately made from bolted-together

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

tube and covered with heat-shrunk

Dacron Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods ...

fabric. The

wing rib In an aircraft, ribs are forming elements of the airframe structure of a wing, especially in traditional construction. By analogy with the anatomical definition of "rib", the ribs attach to the main spar, and by being repeated at frequent inter ...

s are made from

fiberglass Fiberglass (American English) or fibreglass (English in the Commonwealth of Nations, Commonwealth English) is a common type of fibre-reinforced plastic, fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened i ...

graphite Graphite () is a Crystallinity, crystalline allotrope (form) of the element carbon. It consists of many stacked Layered materials, layers of graphene, typically in excess of hundreds of layers. Graphite occurs naturally and is the most stable ...

rod and

epoxy resin Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also co ...

over

Styrofoam Styrofoam is a brand of closed-cell extruded polystyrene foam (XPS), manufactured to provide continuous building insulation board used in walls, roofs, and foundations as thermal insulation and as a water barrier. This material is light blue in ...

. It has a span wing supported by

lift strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of struts, which act in ...

s and

jury strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of struts, which act in ...

s or, alternatively, cable bracing. Controls are conventional three axis, with the

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement aroun ...

s and

elevator An elevator (American English) or lift (Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems suc ...

controlled by a

center stick A centre stick (or center stick in the United States), or simply control stick, is an aircraft cockpit arrangement where the control column (or joystick) is located in the center of the cockpit either between the Aviator, pilot's legs or between ...

and

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, airship, or other vehicle that moves through a fluid medium (usually air or water). On an airplane, the rudder is used primarily to counter adverse yaw ...

controlled by pedals. The landing gear is a fixed

monowheel gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for taxiing, takeoff or landing. For aircraft, it is generally needed for all three of these. It was also formerly called ''alighting gear'' by some manufacturers, s ...

. The pilot sits on an open cockpit seat without a windshield and is secured with a four-point harness. The aircraft is designed to be car-top transportable and can be assembled by one person. The Goat is designed to be launched by

aerotow Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word ''soaring'' is a ...

behind an ultralight aircraft,

auto-tow Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word ''soaring'' is a ...

winch-launch Gliding is a recreational activity and competitive air sports, air sport in which pilots fly glider aircraft, unpowered aircraft known as Glider (sailplane), gliders or sailplanes using naturally occurring currents of rising air in the atmospher ...

or by rolling it down a slope. It is flown for

soaring Soaring may refer to: * Gliding, in which pilots fly unpowered aircraft known as gliders or sailplanes * Lift (soaring), a meteorological phenomenon used as an energy source by some aircraft and birds * ''Soaring'' (magazine), a magazine produced ...

and is not recommended for

aerobatics Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in conventional passenger-carrying flights. The term is a portmanteau of "aeroplane" and "acrobatics". Aerobatics are performed in aeroplanes and gl ...

Operational history

One Goat was flown on a cross-country flight of more than that exceeded .

Variants

;Goat 1 :Initial version, first flown February 1, 2003, with "V"

s and

s that fold onto the wing for transport. Landing gear is a monowheel. Drawings are still available. ;Goat 2 :Lighter-weight version, with a kingpost and

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

cable-bracing in place of struts and push-pull tubes eliminated in favor of cables. Landing gear is a monowheel. Drawings no longer available as it has been replaced by the Goat 4. ;Goat 3 :Short-wing version, with "V" lift struts and jury struts similar to the Goat 1, plus a higher-speed

airfoil An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fl ...

. Drawings are still available. ;Goat 4 :Standard-wing version, uses the cable-braced Goat 2 wing with Goat 3 nose and tail. Drawings are still available.

Specifications (Goat 1)

References

External links

* {{Mike Sandlin aircraft 2000s United States sailplanes Homebuilt aircraft Aircraft first flown in 2003

Design and development

Operational history

Variants

Specifications (Goat 1)

See also

References

External links