F-14 Tomcat Fuselage
The F-14 features engines in separate nacelles, set well apart from each other so that damage to one of them will have minimal effect on the other. The main central and rear area of the fuselage consists of two separate engine nacelles joined together by a shallow flat area known as a pancake”. At the extreme rear of the aircraft, this pancake is little more than a decking between the engine pods. This leaves a deep tunnel between the engines which imposes a small drag penalty. However, it adds to overall lift, gives an extra attachment area for weapons pylons, and provides some additional fuselage space for fuel and equipment. The rear part of the broad between- engines pancake is gently curved upwards to reduce both the supersonic trim drag and the negative zero-lift supersonic pitching moment.
At the extreme end of the decking are a fuel dump pipe and housings for ECM antennas. This area of the aircraft has undergone several configuration changes. The first prototypes had a rear empennage that tapered gradually from the engines towards the center of the aircraft. This was found to create excessive drag and turbulence, so various attempts at ‘cutting down’ the empennage were made. Most early aircraft cut approximately ten inches per side, although there were several variations. Late production aircraft had an empennage that was only wide enough to accommodate the fuel dump pipe, chaff dispensers, and various ECM antennas.
The fuselage is an all metal semi-mono- coque structure with machined frames, main longerons of titanium, and light alloy stressed skin. The forward fuselage section comprises the cockpit and an upward hinged radome. The radome itself is manufactured by Brunswick. The center fuselage is a simple fuel carrying box structure. The rear fuselage was initially manufactured by Fairchild Republic and is a large flat section with an airfoil shaped cross section which provides more than half of the aircraft’s lifting surface.
The speed brake is in two parts and three pieces. The upper surface, located between the tails, is one piece and is actuated by two hydraulic cylinders to a maximum deflection of 60°. The lower part is in two pieces, each operated by a single actuator that are linked together, and also has a maximum deflection of 60′. Maximum extension is accomplished in less than two seconds.
To maintain a smooth fill between the trailing edge of the wing and the upper surface of the rear fuselage, the latter incorporates inflatable canvas bags on its upper surface. These are pressurized with engine bleed air via a regulator. Teflon paint on the underside of the wing prevents abrasion of the bags.
Air is admitted to the engines via two large, rectangular-shaped, sharp-lipped intakes, one mounted on each side of the fuselage. The edges of the intakes are swept sharply backward from top to bottom, ensuring that adequate amounts of air get into the engine at high angles of attack. These intakes are mounted well outboard of the fuselage sides, far enough away that turbulent boundary layer air Is kept from entering the engine without the use of complex diffuser systems such as those fitted to the F-4. Because of the overall dihedral of the wing glove box, the intakes are canted outwards at the bottom. However, even at the top of the intakes where they are closest to the fuselage, the inner wall of the intake is still over eight inches away from the fuselage.