A folding wing is a design feature of aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 to save space in the airfield, and time, and is typical of naval aircraft that operate from the limited deck space of aircraft carrier

Aircraft carrier

An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

s. The folding allows the aircraft to occupy less space in a confined hangar

Hangar

A hangar is a closed structure to hold aircraft or spacecraft in protective storage. Most hangars are built of metal, but other materials such as wood and concrete are also sometimes used...

 because the folded wing normally rises over the fuselage

Fuselage

The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...

 decreasing the floor area of the aircraft. Vertical clearance is also limited in aircraft carrier hangar deck

Hangar

A hangar is a closed structure to hold aircraft or spacecraft in protective storage. Most hangars are built of metal, but other materials such as wood and concrete are also sometimes used...

s. In order to accommodate for this, some aircraft such as the Supermarine Seafire

Supermarine Seafire

The Supermarine Seafire was a naval version of the Supermarine Spitfire specially adapted for operation from aircraft carriers. The name Seafire was arrived at by collapsing the longer name Sea Spitfire.-Origins of the Seafire:...

 and Fairey Gannet

Fairey Gannet

The Fairey Gannet was a British carrier-borne anti-submarine warfare and airborne early warning aircraft of the post-Second World War era developed for the Royal Navy's Fleet Air Arm by the Fairey Aviation Company...

 have additional hinges to fold the wingtips downward, while others such as the S-3 Viking

S-3 Viking

The Lockheed S-3 Viking is a four-seat twin-engine jet aircraft that was used by the U.S. Navy to identify, track, and destroy enemy submarines. In the late 1990s, the S-3B's mission focus shifted to surface warfare and aerial refueling. The Viking also provided electronic warfare and surface...

 have folding tails.

Short Brothers

Short Brothers

Short Brothers plc is a British aerospace company, usually referred to simply as Shorts, that is now based in Belfast, Northern Ireland. Founded in 1908, Shorts was the first company in the world to make production aircraft and was a manufacturer of flying boats during the 1920s, 1930s, and 1940s...

, the world's first aircraft manufacturer, developed and patented

Patent

A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 folding wing mechanisms for ship-borne aircraft (Short Folder

Short Folder

Short Folder is a generic name often applied to several different Short Brothers' aircraft types designed and built prior to and during World War I...

), the first patent being granted in 1913. The wings were hinged so that they folded back horizontally alongside the fuselage., usually being held in place by latches projecting sideways from the rear of the fuselage

Fuselage

The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...

.

Since the monoplane supplanted the biplane in the late 1930s, virtually all fixed-wing aircraft designed for shipboard duty

Navalised

A navalised aircraft is an aircraft that has been specifically designed for naval use, in some cases as a variant of a land-based design.-Characteristics:...

 have been equipped with folding wings. Notable exceptions include the SBD Dauntless, F2A Buffalo, and A4D/A-4 Skyhawk (all USN types) and the Sea Harrier

BAE Sea Harrier

The British Aerospace Sea Harrier is a naval VTOL/STOVL jet fighter, reconnaissance and attack aircraft, a development of the Hawker Siddeley Harrier. It first entered service with the Royal Navy in April 1980 as the Sea Harrier FRS1 and became informally known as the "Shar"...

 (British). All four are relatively small designs.

A folding wing has disadvantages over a fixed wing. It will be heavier and have complex connections for electrical, fuel

Fuel

Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

, aerodynamic and structural systems.
Many naval helicopter

Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

s have rotor blade

Helicopter rotor

A helicopter main rotor or rotor system is a type of fan that is used to generate both the aerodynamic lift force that supports the weight of the helicopter, and thrust which counteracts aerodynamic drag in forward flight...

s that can be aligned over the fuselage to save space onboard the ship.

Folding surfaces are rare among land-based designs, and are used on aircraft that are tall or too wide to fit inside service hangars. Examples include the Boeing B-50 Superfortress

Boeing B-50 Superfortress

The Boeing B-50 Superfortress strategic bomber was a post-World War II revision of the Boeing B-29 Superfortress, fitted with more powerful Pratt & Whitney R-4360 radial engines, stronger structure, a taller fin, and other improvements. It was the last piston-engined bomber designed by Boeing for...

 (folding tail) and Sukhoi Su-47

Sukhoi Su-47

The Sukhoi Su-47 Berkut , also designated S-32 and S-37 during initial development, was an experimental supersonic jet fighter developed by Sukhoi Aviation Corporation...

 (folding wings). The Saab 37 Viggen and the Boeing 377 Stratocruiser have foldable rear fins that make them lower for entering hangars.