F-14 Wings

The variable-geometry wings have 20° of lead­ing edge sweep in the fully forward position and 69° when fully swept. An oversweep posi­tion of 75° is provided for carrier stowage and can only be engaged manually on the ground. The wing position is programmed automatical­ly for optimum performance throughout the flight regime, but manual override is provided. A short movable wing outer panel, needing a comparatively light pivot structure, results from a wide fuselage and fixed center-section glove, with pivot points 8 feet 11 inches from the centerline of the airframe. The inboard wing section, adjacent to the fuselage, arcs upward slightly to minimize cross-sectional area and wave drag. It consists of a one-piece electron beam-welded Ti-6A1 -4V titanium alloy assembly, 22 feet in span. Each wing “mates with its pivot points via two sets of lugs, one of which may fail without endangering the air­craft. The wing surfaces, slats, flaps and spoil­ers are manufactured by Kaman Aerospace while Hamilton-Standard builds the wing sweep actuators.

 Two small triangular-shaped vanes are mounted on the leading edge of the wing gloves on the F-14A. These vanes are normal­ly retracted, but are extended at supersonic speeds under the control of the air-data com­puter. The vanes generate additional lift ahead of the aircraft’s center of gravity, which helps to compensate for a nose-down pitching moment that takes place at supersonic speeds. These vanes are automatically de­ployed when the speed exceeds Mach 1.4 in order to push up the nose and unload the tailplanes, giving them sufficient authority to pull 7.5 g at Mach 2. The vanes can be manu­ally deployed between Mach 1.0 and Mach 1.4. but will not operate when the wing sweep is less than 35°. F-14B and F-14D aircraft do not have the glove vanes. Starting with block 135, the F-14A incorporated two small bulged antennas on the underside of each glove for the AN/ALQ-126 ECM sys­tem. Aircraft equipped with the AN/ALR-67 system added an additional blister to this area on each side.

Normal control of the wing sweep modes is via a four-way mode switch on the inboard side of the right throttle grip. In an emergency, wing sweep position can be manually selected with an emergency WING SWEEP handle on the inboard side of the throttle quadrant. The emergency handle is directly connected to the wing sweep hydraulic valves, and completely bypasses the automatic flight control system and computers. In BuNo 159825 and subse­quent aircraft, the emergency WING SWEEP handle incorporates locks in 4° increments between 20° and 68° to eliminate random wing movement should electrical transients be experienced.

 When the wing sweep selector is In AUTO, wing sweep is controlled by the central air data computer (CADC). The wing is automati­cally positioned, primarily as a function of Mach number, but includes some pressure altitude biasing. The wing is positioned to the optimum sweep angle for developing maxi­mum maneuvering performance.

 Alternately, the pilot can adjust wing sweep via the FWD and AFT positions of the four-way mode switch. The CADC will not allow the pilot to select a wing sweep that might potentially cause structural damage the aircraft or com­promise its ability to fly.

 The BOMB position on the four-way mode switch is used during ground attack. This mode has always existed on the Tomcat, although it has only recently found a use. If the wing sweep is less than 55° when BOMB is selected, the wings will drive to 55°. If the wing sweep is already greater than 55°, the wings will not move. If the maneuvering flaps are extended, they will retract and the wings will sweep to 55°. On F-14A aircraft, if the speed is greater than Mach 0.35, the glove vanes will automatically extend. The wings will continue to follow the automatic program commanded by the CADC, with the exception that the wings will not sweep forward to less than 55° while the mode selector remains in BOMB. This controlled movement eliminated a num­ber of variables that would otherwise have to be factored into the weapons release formulas in the computers, simplifying development and allowing faster solutions.

 The wing has no conventional ailerons, roll control being provided at low speeds by wing- mounted spoilers and at high speeds by the differentially-moving horizontal tailplane. The full-span trailing edge flaps have a small inboard section and a larger outboard section. These flaps are deliberately made inoperative when the wing is swept back to prevent dam­age. Leading-edge maneuvering slats occupy virtually the full span of the outer wing panel leading edge. To improve combat maneuver­ability, the slats and outboard flap sections can be deployed while the wing is in the fully- forward position. When wing sweep is greater than 57°, the wing spoilers are locked down, and roll control is provided completely by the differentially-moving horizontal stabilizers. Should the wings get stuck in the fully-aft position, the F-14 can still land safely at 200 mph with 4,000 pounds of fuel or at 166 mph with 2,000 pounds of fuel, in spite of the fact that the wing flaps are inoperative when the wing is swept.

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