Grumman F6F Hellcat


In the lower part of the space between the fire-wall and the first frame was a reserve 284 liter fuel tank. Like all the others, it had self-sealing properties. The cockpit started just behind the rear surface of the reserve fuel tank. Also in this location, under the cockpit floor, the central spar was mounted to the fuselage. The mobile part of the canopy, moved by turning a crank, could also be thrown off in an emergency. The technically complicated windscreen of the F6F-3 was replaced in the F6F-5 by a much simpler but equally tough one.
The main instrument panel was equipped with an Mk.8 reflex sight. The joystick had a “gun handle” typical for American fighters. It contained a firing lock and a bomb release trigger. The pilot’s seat, similar in construction to its counterpart in the F4U Corsair, held the pilot’s seat parachute. In its lower part it also contained some free space for the so-called “jungle-pack” – a set of various emergency equipment such as a raft/dinghy. An armor plate behind the pilot’s seat separated him from the rear part of the fuselage, which held an 8,4 liter splinter-safe oxygen tank, a “boost” tank (containing hydro-methanol liquid) and an emergency breaking-hook installation. The most important detail filling the space behind the cockpit however was an AN/ARC-1/5 transceiver, an AN/ARR-2 homing device, and an IFF (Identification Friend or Foe) panel. On top of the fuselage behind the cockpit, besides an antennae mast, there was an identification light (a rear light was located under the rudder). All of the electrical devices (and there were many) in the F6F were powered by a single-cable, 28-Volt installation.
Under the rear part of the fuselage were located compartments containing the retractable tail wheel and the amortized breaking hook.
The trapezoidal, semi-monocoque wing, with a surface of almost 32 m2, consisted of the middle-wing containing two main fuel tanks (331 liters each) and main under-carriage compartments, and of folding outer wings. The bearing elements of the whole construction were three spars – two main ones and one supporting one – flush riveted to the working skin, ribbing and longerons. The wingtips were formed from aluminum. In the unfolded position (7,5% dihedral) all of the main spar elements were immobilized with diagonal bolts. Instead of placing it perpendicularly to the wing’s surface, the vertical spar surface had its lower part leaned forward, which ensured a better distribution of maximal stress between the main undercarriage and the spar – stress which was dangerous especially during landings. The most important task of the pilot just after the plane stopped to a halt after landing was to open the lock which enabled the deck personnel to manually fold the wings. This lowered the plane’s width to less than five meters, which was even less than the length of the elevator unit (564 cm). Located underneath the center section of the wing were (rarely used) mountings for the catapult.
The ailerons had a surface of 1,46 m2, an aluminum frame and were fabric covered. They were attached to the wings’ trailing edges on three hinges and were moved between positions +17° and –13,4°. The left aileron was fitted with a small, in-flight adjustable flap. The right flap had to be adjusted on the ground, however. “Crocodile” type flaps built into the trailing edge were divided into four parts. Every pair of flaps, which had a surface of 3,7 m2, could be pushed out (classically or in emergency) by hydraulic servo-motors to up to –50°. An additional servo-mechanism served as a safety motor which folded the flaps automatically if the flying speed exceeded 315 km/h. Mounted close to the end of the right wing’s leading edge was a Pitot tube.

“White 14” from VF-44 leaving catapulta on USS “Langley”. Course – Leyte gulf. [Via Andre R. Zbiegniewski]


Wings upper surfaces were provided with armament maintenance access hatches. Under the ammunition containers there were shell extractor outlets (three per wing). Wing armament compartments held three “half-inch” (0.5 cal = 12.7 mm) Colt-Browning M-2 machine guns with 400 rounds of ammunition each. The inner machine gun barrels were located 234 cm away from the plane’s axis. The outer ones – 271 cm. In a few F6F-3N’s and all F6F-5N’s the inner machine guns were replaced with 20-millimeter M-2 guns supplied with 200 bullets each. The four inner machine guns were left unchanged in the Hellcat’s night version. According to factory instructions, the armament harmonization point was located 274 meters in front of the plane, although in practice it was often “shortened” in field conditions on pilot’s request. The accuracy of fire of the F6F’s ­daytime versions was registered by means of a camera gun mounted into the central part of the left wing’s leading edge.
The control surfaces: monocoque, ribbed, aluminum-framed. With fabric covered movable elements. Its total surface – excluding the upwards angled horizontal stabilizers – was 7.23 m2, and the elevator was 2.39 m2. The fin’s surface was 4.84 m2.
The rudder, equipped with a trimmer on its trailing edge, could turn 33° left and right. The elevators also had trimmers and had a mobility of 26° upwards and 15° downwards. The tips of the control surfaces were aluminum prefabricates.
The F6F’s engine was an air-cooled 18-cylinder Pratt & Whitney R-2800-10W Double Wasp with 2000 KM take-off power and with its axis leaning 3° down away from the plane’s axis. It was supported by a double-speed, double-stage automatic compressor and a multiplying gear. The whole system powered a three-bladed constant-speed (adjustable between 26-65°) Hamilton Std airscrew with a diameter of 3988 mm. The propeller clearance didn’t exceed 186 mm.
The completely retractable undercarriage consisted of two (3,35 mm apart) main undercarriage shanks integrated with the central wing spar which were retracted chordwise and turned by 90° in the process. The tail wheel turned by 180° during retracting. All three undercarriage legs were locked in the open position (the so-called “zero” position) by means of bolts. When retracted, the undercarriage was covered by a system of flaps and covers, which left only the bottom parts of the wheels uncovered (the breaks and dampers were hydraulic). The tires of the main undercarriage were normal pressurized ones while the tail wheel, in accordance with the US Navy tradition, was a solid rubber one.
Bendix company, the producer of the Hellcat’s fuel system – adapted for 100/130 aviation fuel – ensured that to extend the F6F’s range it was possible to attach an auxiliary fuel tank under the middle section of the wing. The tank had 568 liter capacity and came in two versions: aluminum (earlier) and steel (later). Additional under-wing tanks could carry 379 liters of petrol. A light signaling system located on the instrument panel informed the pilot if the total fuel level dropped below 189 liters or if it was necessary to turn on the manual fuel pump when the main pump (mounted on the engine), or the whole installation, broke down.

F6F-3, VF-27 squadron, pilot Captain Dick Stambook, USS “Princeton”, 1944. [Painted by Zygmunt Szeremeta]


F6F’s hydraulic systems, filled with a red “Hydrol” liquid, were also used – besides the mechanisms, breaks and undercarriage shock absorbers – in the following sub-assemblies: all sorts of flaps, cooler valves, intercoolers, armament mechanisms and wing lock-in systems.
Located near the central, universal mount under the fuselage, to its left and right, were bomb pylons which could hold, in the F6F-3 version, two 227-kilogram (500-pound) bombs. In the F6F-5 their capacity rose to two 454-kilogram (1000-pound) bombs and was additionally supplemented by six (three per wing) “Zero-Length Mk.5” rails for unguided, universal HVAR rockets (127 mm cal.).

[…]

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