Folding wing

A folding wing is a wing configuration design feature of aircraft to save space and is typical of carrier-based aircraft that operate from the limited deck space of aircraft carriers. The folding allows the aircraft to occupy less space in a confined hangar because the folded wing normally rises over the fuselage decreasing the floor area of the aircraft. Vertical clearance is also limited in aircraft carrier hangar decks. In order to accommodate for this, some aircraft such as the Supermarine Seafire and Fairey Gannet have additional hinges to fold the wingtips downward, while others such as the S-3 Viking have folding tails. The F-14 Tomcat's variable-sweep wings could be "overswept" to occupy less space.

History

Short Brothers, the world's first aircraft manufacturer, developed and patented folding wing mechanisms for biplane ship-borne aircraft like their Short Folder, the first patent being granted in 1913. The Folder's biplane 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.

The Douglas TBD Devastator was the first naval aircraft to feature hydraulic folding wings.

Description

Since the monoplane supplanted the biplane in the late 1930s, virtually all fixed-wing aircraft designed for shipboard duty have been equipped with folding wings. Notable exceptions include the SBD Dauntless, F2A Buffalo, and A4D/A-4 Skyhawk (all USN types); the Mitsubishi A5M and Yokosuka D4Y (Japanese); and the Sea Harrier (British). All six are relatively compact designs. Exceptions which are currently in use, as of 2021, include the Dassault Rafale, the Lockheed Martin F-35B, and the McDonnell Douglas AV-8B Harrier.

The Grumman-patented ''Sto-Wing'' aftwards-folding wing folding system, pioneered on the Grumman F4F-4 ''Wildcat'', has been used since World War II on a number of Grumman-designed carrier aircraft, a version of which is still in use in the 21st century on the Grumman E-2 Hawkeye shipboard airborne early warning (AEW) aircraft and its C-2 Greyhound derivative.

Another Grumman naval aircraft, the F-14 Tomcat, had variable-sweep wings that could be swept between 20° and 68° in flight. For parking, the wings could be "overswept" to 75°.

A folding wing has some disadvantages compared to a non-folding wing. It is heavier and has more complex connections for electrical, fuel, aerodynamic, and structural systems.

Many naval helicopters have rotor blades that can be aligned over the fuselage to save space on board ships.

Folding surfaces are rare among land-based designs and are used on aircraft that are too tall or too wide to fit inside service hangars. Examples include the Boeing B-50 Superfortress and its folding tail. The Saab 37 Viggen and the Boeing 377 Stratocruiser have foldable rear fins that make them lower for entering hangars. The Boeing 777 (classic) twinjet wide-body airliner was offered with folding wingtips for confined airports. The new Boeing 777X models feature a shorter and simpler folding wingtip than was planned for the earlier Boeing 777. This will provide an extra of total wingspan in flight, yet the plane will still fit inside the same airport gates as the 777-200LR/777-300ER.

Gallery

Simple fold

File:Short Folder S.64 IWM Q 090115.jpg, Short Folder S.64 being hoisted aboard the cruiser HMS ''Hermes'' (horizontal fold)
File:Folding_wing_of_De_Havilland_Sea_Vixen.JPG, De Havilland Sea Vixen
File:hawker.sea.fury.folded.arp.jpg, Hawker Sea Fury
File:sea hawk wv908 frontview arp.jpg, Hawker Sea Hawk FGA.6
File:Super Hornet on flight deck.jpg, F/A-18E/F Super Hornet
File:F-8H VF-111 CVA-14 1969.jpg, F-8H in an elevator
File:Buccaneer S 2 - Elvington - BB.jpg, RAF Buccaneer S.2
File:F11F-1 Tiger on USS Forrestal (CVA-59) in April 1956.jpg, An F11F Tiger with downward-folded wingtips
File:North American XB-70A Valkyrie in flight (cropped).jpg, North American XB-70 Valkyrie
File:777X Roll-Out (40407369583).jpg, folding wingtip of a Boeing 777X

Aftward fold

Image:F6F-3 fighters landing on USS Enterprise (CV-6).jpg, Grumman F6F Hellcats of the US Navy. The patented ''Sto-Wing'' system was common to Grumman fighters of World War II.
File:Supermarine Walrus Argentine Navy (4446497743).jpg, Argentinian Supermarine Walrus on a cruiser.
File:Grumman E-1B 147223 RVAW-110 JAX 19.07.76 edited-2.jpg, Grumman E-1 Tracer with ''Sto-Wing'' system folded wings.
Image:Fairey Fulmer.JPG, Fairey Fulmar
Image:Fairey_Firefly_T.7_WM800_Ringway_17.04.53_edited-2.jpg, Fairey Firefly
Image:Seamew folded.jpg, Short Seamew
Image:FS_CdG_Super_Hawkeye.jpg, Grumman E-2 Hawkeye, which still uses a form of Grumman's ''Sto-Wing'' design.

Double fold

Image:Seafire F XVII SX 336 wings up.jpg, Supermarine Seafire
File:Fairey_Gannet_AEW3_AN1152038.jpg, Fairey Gannet
Image:Westland_Wyvern_S.4_VZ765_'181'_Stretton_25.06.55_edited-2.jpg, Westland Wyvern

Rotating wing

Image:V-22 Osprey wing rotated.jpg, A V-22 Osprey with wings rotated parallel to fuselage

Over-swept wings

File:US Navy 040712-N-7532C-051 An F-14 Tomcat taxis to one of four steam-powered catapults during flight operations aboard USS Harry S. Truman (CVN 75).jpg, A Grumman F-14 Tomcat with its wings in the "oversweep" position

Folding-wing aircraft on flight deck

Image:CVE-71 launching FM-2s Samar 25Oct1944.jpg, FM-2 Wildcats on USS ''Kitkun Bay'' (1944)
File:F7U-3 VF-124 on elevator of USS Hancock (CVA-19) c1956.jpg, Vought F7U Cutlass on flight deck elevator
Image:HMS_Victorious_(R38)_aerial_c1959.jpeg, Sea Venoms, Scimitars, and Skyraiders on (circa 1959-1960)
Image:USS Coral Sea (CVA-43) leaving Pearl Harbor in April 1963.jpg, Demons, Crusaders, Skywarriors, Trackers, Tracers, and Skyraiders on USS ''Coral Sea'' (1963)
File:US Navy 031117-N-6213R-035 An S-3B Viking assigned to the.jpg, A Lockheed S-3 Viking on board USS ''John C. Stennis'' (2003)
MAKS-2007-Su-33-1.jpg, Sukhoi Su-33

Notes

Bibliography

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External links

{{commons category-inline, Folding wings

The Case for the Folding Wing – Flying

Naval aviation technology
Aircraft wing components