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 A-5 Vigilante and 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.

In 1935, the Douglas TBD Devastator was the first aircraft to feature hydraulic folding wings, allowing the pilot to fold the wings from the cockpit without requiring other sailors to fold them manually.

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 onboard 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, though this was never ordered. The new Boeing 777X features a shorter and simpler folding wingtip than was planned for the earlier Boeing 777, which will provide an extra of total wingspan in flight, while allowing the airplane to fit inside the same airport gates as the 777-200LR/777-300ER.

Aircraft with ventral fins under the fuselage for stability which had to be folded for takeoff and landing include the Mikoyan-Gurevich MiG-23, the MiG-27, and the Vought XF8U-3 Crusader III.

An example of aircraft using folding wingtips other than stowage/hangar space such as aerodynamics and flight handling was the North American XB-70 Valkyrie. This increased both compression lift and enhanced directional stability at high speeds.

Gallery

Simple fold

File:A-6A VA-65 at NAS North Island 1966.jpeg, Grumman A-6A Intruder
File:777X Roll-Out (40407369583).jpg, folding wingtip of a Boeing 777X
File:Buccaneer S 2 - Elvington - BB.jpg, RAF Buccaneer S.2
File:Folding_wing_of_De_Havilland_Sea_Vixen.JPG, De Havilland Sea Vixen
File:Vought F-8H Crusader of VF-111 on forward elevator of USS Ticonderoga (CVA-14), in 1969.jpg, F-8H in an elevator
File:F11F-1 Tiger on USS Forrestal (CVA-59) in April 1956.jpg, An F11F Tiger with downward-folded wingtips
File:Super Hornet on flight deck.jpg, F/A-18E/F Super Hornet
File:hawker.sea.fury.folded.arp.jpg, Hawker Sea Fury
File:sea hawk wv908 frontview arp.jpg, Hawker Sea Hawk FGA.6
Mikoyan-Gurevich MiG-29K ‘RF-92324 - 48 blue’ (36928677816).jpg, MiG-29K at ARMY 2017
File:Short Folder S.64 IWM Q 090115.jpg, Short Folder S.64 being hoisted aboard the cruiser HMS ''Hermes'' (horizontal fold)
MAKS-2007-Su-33-1.jpg, Sukhoi Su-33 at MAKS 2007
File:North American XB-70A Valkyrie in flight (cropped).jpg, North American XB-70 Valkyrie
Yakovlev Yak-38 frontview .jpg, Yakovlev Yak-38
Yakovlev Yak-141 in 2009 (2).jpg, Yakovlev Yak-141

Aftward fold

Image:Fairey Fulmer.JPG, Fairey Fulmar
Image:Fairey_Firefly_T.7_WM800_Ringway_17.04.53_edited-2.jpg, Fairey Firefly
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:FS_CdG_Super_Hawkeye.jpg, Grumman E-2 Hawkeye, which still uses a form of Grumman's ''Sto-Wing'' design.
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.
MAKS2015part5-05.jpg, Kamov Ka-52K stub wings
Image:Seamew folded.jpg, Short Seamew
File:Supermarine Walrus Argentine Navy (4446497743).jpg, Argentinian Supermarine Walrus on a cruiser.

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

Folding rotors

Ka-32S-1997.jpg, Ka-32S at MAKS 1997
Russian Navy, Kamov, Ka-52K (21444723505).jpg, Kamov Ka-52K.
MAKS Airshow 2019 (2019-08-30) 432.jpg, Kamov Ka-226
US Navy 100223-N-7948R-007 A member of the flight crew folds the wings of a CH-46 Sea Knight helicopter after flight operations aboard the amphibious assault ship USS Peleliu (LHA 5).jpg, CH-46 Sea Knight
File:SikorskyCH124SeaKing07A.JPG, Sikorsky CH-124 Sea King
SH-60K helicopter during tail folding.jpg, Sikorsky SH-60K
File:25th CAB storm preparations 140807-A-NN814-029.jpg, Sikorsky UH-60M
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 decks

File:A-1J of VA-196 on USS Bon Homme Richard (CVA-31) 1964.jpg, A-1J of VA-196 on USS Bon Homme Richard
Image:HMS_Victorious_(R38)_aerial_c1959.jpeg, Sea Venoms, Scimitars, and Skyraiders on (circa 1959-1960)
Image:CVE-71 launching FM-2s Samar 25Oct1944.jpg, FM-2 Wildcats on USS ''Kitkun Bay'' (1944)
Soviet cruiser Admiral Isachenkov underway aerial port quarter view 1985.jpg, Kamov Ka-25 on the helideck of cruiser ''Admiral Isachenkov''
File:Aircraft carrier "Minsk" in 1980.jpeg, Ka-25 Hormone and Yak-38 Forger parked on the flight deck of the Soviet aircraft carrier ''Minsk''.
Storing a Russian Navy Kamov Ka-27PS (RF-34145) (4).jpg, Ka-27PS
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)
File:SH-3A Sea King of HS-6 aboard USS Kearsarge (CVS-33), circa in 1964 (NNAM.2011.113.378).jpg, SH-3A Sea King of HS-6 aboard USS Kearsarge (CVS-33), circa 1964
File:Vice_Admiral_Ajendra_Bahadur_Singh,_Flag_Officer_Commanding-in-Chief_Western_Naval_Command,_embarked_ships_of_Western_Fleet_off_the_West_Coast_of_India_from_11_to_13_October_2022,_to_review_readiness_of_the_Fleet_02.jpg, Indian Navy MiG-29K
551-baltimora-19.jpg, SH-3D/H Sea King on Italian aircraft carrier Giuseppe Garibaldi
File:Cubierta de vuelo del L-61, parte de popa (34258720604).jpg, SH-3D/H Sea King on Spanish aircraft carrier ''Juan Carlos I''
File:F7U-3 VF-124 on elevator of USS Hancock (CVA-19) c1956.jpg, Vought F7U Cutlass on flight deck elevator
File:A3J-1s VAH-7 CVAN-65 NAN11-62.jpg, North American A-5 Vigilante on flight deck. Note the folded Vertical stabilizer
File:Yak-38 fighters on Soviet carrier Minsk in 1980.jpg, Yak-38 on Soviet carrier Minsk, 1980

See also

*Index of aviation articles

Notes

Bibliography

*

External links

{{commons category, Folding wings

The Case for the Folding Wing – Flying

Naval aviation technology
Aircraft wing components