Aircraft

[2] Part 1 [3] (Definitions and Abbreviations) of Subchapter A of Chapter I of Title 14 of the U. S. Code of Federal Regulations states that aircraft "means a device that is used or intended to be used for flight in the air."

Small hot-air balloons, called sky lanterns, were first invented in ancient China prior to the 3rd century BC and used primarily in cultural celebrations, and were only the second type of aircraft to fly, the first being kites, which were also first invented in ancient China over two thousand years ago (see Han Dynasty).

Huge powered aerostats, characterized by a rigid outer framework and separate aerodynamic skin surrounding the gas bags, were produced, the Zeppelins being the largest and most famous.

Rocket-powered missiles that obtain aerodynamic lift at very high speed due to airflow over their bodies are a marginal case.

Man-powered aircraft also rely on ground effect to remain airborne with minimal pilot power, but this is only because they are so underpowered—in fact, the airframe is capable of flying higher.

Rotorcraft, or rotary-wing aircraft, use a spinning rotor with aerofoil cross-section blades (a rotary wing) to provide lift.

The largest aircraft by dimensions and volume (as of 2016) is the 302 ft (92 m) long British Airlander 10, a hybrid blimp, with helicopter and fixed-wing features, and reportedly capable of speeds up to 90 mph (140 km/h; 78 kn), and an airborne endurance of two weeks with a payload of up to 22,050 lb (10,000 kg).

[21][24] The 8-engine, piston/propeller Hughes H-4 Hercules "Spruce Goose" — an American World War II wooden flying boat transport with a greater wingspan (94m/260 ft) than any current aircraft and a tail height equal to the tallest (Airbus A380-800 at 24.1m/78 ft) — flew only one short hop in the late 1940s and never flew out of ground effect.

[28] The fastest manned, air-breathing powered airplane is the Lockheed SR-71 Blackbird, a U.S. reconnaissance jet fixed-wing aircraft, having reached 3,530 km/h (2,193 mph) on 28 July 1976.

Take-off may be by launching forward and downward from a high location, or by pulling into the air on a tow-line, either by a ground-based winch or vehicle, or by a powered "tug" aircraft.

The first practical, controllable example was designed and built by the British scientist and pioneer George Cayley, whom many recognise as the first aeronautical engineer.

Kytoons are balloon-kite hybrids that are shaped and tethered to obtain kiting deflections, and can be lighter-than-air, neutrally buoyant, or heavier-than-air.

Aircraft are designed according to many factors such as customer and manufacturer demand, safety protocols and physical and economic constraints.

A balloon similarly relies on internal gas pressure, but may have a rigid basket or gondola slung below it to carry its payload.

Lighter-than-air types are characterised by one or more gasbags, typically with a supporting structure of flexible cables or a rigid framework called its hull.

Smaller designs sometimes use flexible materials for part or all of the structure, held in place either by a rigid frame or by air pressure.

[32][33][35][37] The flight envelope of an aircraft refers to its approved design capabilities in terms of airspeed, load factor and altitude.

When an aircraft is abused, for instance by diving it at too-high a speed, it is said to be flown outside the envelope, something considered foolhardy since it has been taken beyond the design limits which have been established by the manufacturer.

For an unpowered aircraft, the maximum flight time is limited by factors such as weather conditions and pilot endurance.

The three critical flight dynamics parameters are the angles of rotation around three axes which pass through the vehicle's center of gravity, known as pitch, roll, and yaw.

Since the widespread use of digital computers, it is increasingly common for designs to be inherently unstable and rely on computerised control systems to provide artificial stability.

Pitch and yaw stabilities of conventional fixed wing designs require horizontal and vertical stabilisers,[46][47] which act similarly to the feathers on an arrow.

Tandem wing and tailless aircraft rely on the same general rule to achieve stability, the aft surface being the stabilising one.

A balloon is typically very stable in pitch and roll due to the way the payload is slung underneath the center of lift.

Control systems are also sometimes used to increase or decrease drag, for example to slow the aircraft to a safe speed for landing.

Aircraft permit long distance, high speed travel and may be a more fuel efficient mode of transportation in some circumstances.

They are also relatively noisy compared to other forms of travel and high altitude aircraft generate contrails, which experimental evidence suggests may alter weather patterns.

Commercial aircraft include types designed for scheduled and charter airline flights, carrying passengers, mail and other cargo.

General aviation is a catch-all covering other kinds of private (where the pilot is not paid for time or expenses) and commercial use, and involving a wide range of aircraft types such as business jets (bizjets), trainers, homebuilt, gliders, warbirds and hot air balloons to name a few.

A model aircraft is a small unmanned type made to fly for fun, for static display, for aerodynamic research or for other purposes.