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Further Reading

F-14 Tomcat

Design

The Grumman F-14, the world's premier air defense fighter, was designed to replace the F-4 Phantom II fighter (phased out in 1986). F-14s provided air cover for the joint strike on Libyan terrorist targets in 1986. The F-14A was introduced in the mid-1970s. The upgraded F-14A+ version, with new General Electric F-110 engines, now widespread throughout the fleet, is more than a match for enemy fighters in close-in, air combat.

The AWG-9 is a pulse-Doppler, multi-mode radar with a designed capability to track 24 targets at the same time while simultaneously devising and executing fire control solutions for 6 targets. Designed in the 1960's and one of the oldest air-to-air radar systems, the AWG-9 is still the most powerful and new software will increase its capabilities for the 21st century.

The cockpit is fitted with a Kaiser AN/AVG-12 Head-Up Display (HUD) co-located with an AN/AVA-12 vertical situation display and a horizontal situation display. A Northrop AN/AXX-1 Television Camera Set (TCS) is used for visual target identification at long ranges. Mounted on a chin pod, the TCS is a high resolution closed circuit television system with two cockpit selectable Fields Of View (FOV), wide and narrow. The selected FOV is displayed in the cockpit and can be recorded by the Cockpit Television System. A new TCS, in development, will be installed in all three series aircraft. Electronic Support Measures (ESM) equipment include the Litton AN/ALR-45 radar warning and control system, the Magnavox AN/ALR-50 radar warning receiver, Tracor AN/ALE-29/-39 chaff/flare dispensers (fitted in the rear fuselage between the fins), and Sanders AN/ALQ-100 deception jamming pod.

The Tomcat has an internal 20-mm Vulcan Gatling-type gun fitted on the left side, and can carry Phoenix, Sparrow, and Sidewinder AAMs. Up to 6 Phoenix missiles can be carried on 4 fuselage stations between the engines and on 2 pylons fitted on the fixed portion of the wing; 2 Sidewinder AAM can be carried on the wing pylons above the Phoenix mount. Although the F-14 was tested with conventional "iron" bombs on its external hardpoints in the 1960s, the BRU-10 ejection racks were not strong enough to provide a clean separation. Tests in 1988-1990 showed that BRU-32 racks could drop Mk 80-series bombs safely. Later tests would qualify the AGM-88 HARM and the AGM-84 Harpoon.

The design of the F-14B allows for incredible pitch authority as well as good roll control to produce an extremely agile fighter. Rolling maneuvers are accomplished through the use of differential horizontal stabilator and 8 spoilers located on top of the wings. Its general arrangement consists of a long nacelle containing the large nose radar and 2 crew positions extending well forward and above the widely spaced engines. The engines are parallel to a central structure that flattens towards the tail; butterfly-shaped airbrakes are located between the fins on the upper and lower surfaces. Altogether, the fuselage forms more than half of the total aerodynamic lifting surface. With the wings in the 20 degree position most of the lifting force comes from the wings, in the 68 degree position over 60% of the lift is generated from the fuselage itself.

The wing carry-through is one-piece electron beam-welded structure of TI-6A1-4V titanium alloy with 6.71m span. Fuselage has machined frames, titanium main longerons and light alloy stressed skin; centre-fuselage is fuel-carrying box; radome hinges upwards for access to radar; fuel dump pipe at extreme tail; fins and rudders of light alloy honeycomb sandwich; tailplanes have multiple spars, honeycomb trailing-edges and boron/epoxy composites skins.

The wings are shoulder-mounted and are programmed for automatic sweep during flight, with a manual override provided. It's adjustable wing design provides amazing versatility between blazing speed and turn performance. The wings can be adjusted automatically by an onboard computer or manually by the pilot for optimum performance at all altitudes and airspeeds. The twin, swept fin-and-rudder vertical surfaces are mounted on the engine housings and canted outward. The wing pivot carry- through structure crosses the central structure; the carry through is 22 ft (6.7 m) long and constructed from 33 electron welded parts machined from titanium; the pivots are located outboard of the engines. Normal sweep range is 20 to 68 deg with a 75-deg "oversweep" position provided for shipboard hangar stowage; sweep speed is 7.5 deg per second. The fixed glove has dihedral to minimise cross-sectional area and reduce wave drag. Small canards on F-14A known as glove vanes extend forward progressively to 15° from inboard leading-edge to balance supersonic trim change and unload tail surfaces.

There are important differences in the wing geometry of the F-14 and F-111. In terms of the wing semispan in the low sweep position, the pivot of the F- 14A is 10 to 12 percent farther outboard than that of the F-111. The more outboard pivot location results in a much reduced rearward movement of the center of lift with increasing sweep angle. As a consequence, trim drag is reduced and available pitch-control power is increased. The favorable effect of locating the pivot in the proper outboard position is, of course, in accordance with NASA basic research.

Lateral control is achieved by long-span spoilers, ahead of flaps, and tailerons. Automatic leading-edge slats assist maneuvering, and strakes emerge from the wing glove leading-edge at high airspeeds. The automatic wing sweep has manual override, with automatic scheduling of control with airspeed and autostabilisation and angle of attack protection provided by the autopilot and automatic carrier landing system (ALCS). Airbrake panels are located above and below tail, between the twin fins and rudders. For roll control below 57 deg, the F-14 uses spoilers located along the upper wing near the trailing edge in conjunction with its all-moving, swept tailplanes, which are operated differentially; above 57-deg sweep, the tailplanes operate alone. For unswept, low-speed combat maneuvering, the outer 2 sections of trailing edge flaps can be deployed at 10 deg and the nearly full-span leading-edge slats are drooped to 8.5 deg. At speeds above Mach 1.0, the glove vanes in the leading edge of the fixed portion of the wing extend to move the aerodynamic center forward and reduce loads on the tailplane.

The sharply raked, 2-dimensional 4-shock engine intakes have 2 variable-angle ramps, a bypass door in the intake roof, and a fixed ramp forward; exhaust nozzles are mechanically variable. Viewed from ahead, the top of the intakes are tilted toward the aircraft centerline; from above, the engines are canted outward slightly to reduce interference between intake airflow and the fuselage boundary layer. The engines exhaust through mechanically variable, convergent-divergent nozzles.

The landing gear is of the retractable tricycle type. Twin-wheel nose unit and single-wheel main units retract forward, main units inward into bottom of engine air intake trunks. Arrester hook under rear fuselage, housed in small ventral fairing.

The tail control surfaces on F-14s are known as "rolling tails", in that the aircraft does not have ailerons on the wings to control roll. Roll control is instead provided at low speeds by wing-mounted spoilers and at high speeds by differential horizontal stabilizer deflection. This configuration also produces side force, or yaw, which contributed to the inadvertent spin entries. This large tail configuration is to aid in takeoff from aircraft carriers, by providing more pitch moment.

The F-14's fuel system is one of the very first things technicians check when the Tomcat pulls in for scheduled maintenance. Any leak in the fuel system can be critical, even one that isn't visible to the human eye. Finding the smaller leaks can be extremely difficult. Current maintenance practice involves a low-tech approach to finding larger leaks - having technicians run their bare hands along the accessible areas of the fuel line. However, this hands-on approach can miss small leaks completely, or when small leaks are felt by technicians, the precise location may not be readily apparent if the leak is covered by a flange or coupling.