Grumman F6F Hellcat

Grumman F6F Hellcat

Sundowners F6Fs.
The Eleventh Fighter Squadron of the US Navy, known among those

in the know as VF-11 “Sundowners”, had already completed one operational tour. Its location – Guadalcanal – was a recommendation in itself.
Fifty five aerial victories between April and July of 1943 were evidence of the high potential of the personnel, promoted from novice to veteran in a very short time. After its return to the US in August, the unit continued to use its equipment until mid-October, when the last F4F’s were replaced by F6F’s. The Squadron and its 54 pilots, commanded by Commander Gene Fairfax, would not fight on Hellcats for another year.
For VF-11 the second tour really began just in early October, 1944. The unit’s whole personnel were then on board of the aircraft carrier USS “Hornet”. The pilots took over the equipment of the retiring VF-2. The markings of the battered F6F-3s, F6F-5s and F6F-5Ps weren’t changed. The “Sundowners” settled for adding their emblem to the fuselages and began preparing for another combat debut. A part of TF38, the “Hornet” left Manus (Northern Papua) and headed straight for its destination – Nansei Shoto Archipelago. The Japanese airbases scattered on its islands were used by the enemy as refueling stops between Honsiu and Okinawa islands. An inaugural operation carried out on October 10th completely surprised the enemy. Not one Japanese fighter took off to intercept 46 VF-11’s Hellcats; armed with bombs and missiles. The enemy airfields turned out to be empty, which allowed the Americans to attack secondary targets – ports and anchorages.

Six of 38 Hellcats from VF-86 squadron prepare for sweeping over Japan. The day after making this shot (March 19th, 1945) this ship was bombed. [Via Andre R. Zbiegniewski]


Five hundred – and thousand-pound bombs, as well as HVAR missiles, were used as intended to put two enemy ships out of commission. This was mainly due to the determination of Lt Jim Savage’s flight. Despite flying a reconnaissance F6F-5P, he led his men as close to the targets as possible; maneuvering among the dense fire of Japanese AA guns. It wasn’t entirely unsuccessful and managed to claim one of the Hellcats. Ensign Kenneth Chase and his plane were lost. Meanwhile another Ensign, George Lindesmith, won a victory during his patrol to the north of the battle site. The D3A2 Val dive bomber he sent in flames into the sea was the first plane shot down by VF-11 during their second tour.
An unusual mission took off from the “Hornet” on the next day (October 11th). The Hellcats, commanded by LtCdr Fairfax, were now escorting SB2C Helldiver bombers. Each one of them was accompanied by ten F6F’s. This time they encountered no enemy in the air. The moorings of the Japanese fleet, which were full of ships 24 hours earlier, were now almost abandoned. The empty airfields were assaulted with unspecified results. Afterwards the planes returned to their mother ship. That disappointment would be in some respects made up for next day, over Formosa (now Taiwan).
On October 12th, 1944 the “Hornet” and accompanying vessels of TF38 approached Formosa from the east. The first wave of VF-11’s attack sortied while it was still dark. The fighters loaded with bombs and missiles. Since the roadstead of the Hieto port, which had been chosen as the primary target, was empty, the “Sundowners” focused their efforts on nearby airfields. Unfortunately they were surrounded by a ring of efficient AA defenses. The wall of flak soon brought down its first victim – the victor from two days earlier, Ens. Lindesmith. The explosion of a three-inch caliber projectile under Hellcat’s wing disrupted plane’s flight path. The plane was momentarily overturned into a vertical position. The wingtip of the plane caught up with the ground. Tumbling and exploding. Burying the pilot in the wreckage.
Meanwhile a taking off Japanese fighter formation passed right next to the ball of fire. For a moment, the dying flames lit up the orange Hinomarus on the Oscars’ fuselages. This allowed the “Sundowners” to notice the danger. Some still had enough diving speed to easily place themselves behind a Ki-43’s green tail. Spitting fire from all of its machine guns, an F6F shot down one of the enemy planes just as it took off. The undercarriage dropped under the bullet-torn plane. The wreck’s velocity sent it, with the dead pilot inside, over the runway and into a swampy rice paddy. Another green-and-silver Oscar and a similarly-colored Ki-61 Tony managed to climb into the air. Not for long. During the first moments of its laborious climb, the Ki-43 was attacked by Fairfax’s XO, LtCdr Clements. Quickly throttling back, the pilot located his Hellcat just behind the Japanese. From such a perfect position he began firing one short burst after another. Not many were needed to start ripping the Oscar’s thin skin like a lace. After shedding a considerable amount of parts, the Ki-43 left behind one of its horizontal stabilizers. Still, the Japanese pilot followed persistently by the Hellcat, attempted a forced landing. It was unsuccessful and ended in a fatal crash.

The last enemy, a Ki-61, was pursued by all too many Americans. This allowed the slick Tony to climb much higher, while its pursuers got in each other’s way and made it difficult to get a good firing position. VF-11’s situation was at this time complicated also by the constant AA fire. Finally the Ki-61, under heavy but inaccurate fire from six Hellcats, managed to climb high enough to disappear in the low clouds over Hieto. A probable victory over the Japanese plane was attributed to Lt Morris. The other “Sundowners” had to settle for some Nippon’s Eagles destroyed on the ground.
October 13th, 1944 happened to be Friday. The usually superstitious pilots were naturally not entirely indifferent to this fact. The “Hornet’s” whole Air Group was sent on an operation against Takao base. This time under LtCdr Schrader’s command. Initially a couple of “Sundowners” divisions were catapulted from the crowded flight deck. The first was led by Lt Savage. The second – by Lt Dayhoff. It was dawning when the “Hornet’s” Hellcats, heading west at 5000 meters, encountered their comrades from USS “Wasp”. The formations merged and headed for the coast of Formosa. The purpose of their sweep over Hieto was to lure into the air and destroy – either there or on the ground – as many Japanese fighters as possible.

Ground crew’s job was very hard… [Via Andre R. Zbiegniewski]


The planes reached the island’s mountainous eastern coastline without any problems. Further on, the Hellcats were met by an already familiar mass of AA fire, flanking the south-eastern edge of the airfield. There was nothing in the air but a mass of small, dark clouds of flak; but no sign of the enemy. In this situation the VF-11 and VF-14 formation descended as close to the ground as possible. Preparing to attack targets filling the airfields and surroundings of the airbase. There were planes and all kinds everywhere. As well as lots of other military equipment. The sudden change of altitude temporarily freed the Hellcats of the menace of large calibers. They were soon affected by an accurate small arms fire, however. Also, two planes dropping
Ta-Dan fragmentation bombs, already known to the Americans, appeared above them. There were no hits so far, but the F6F’s busily engaged over the airfield had to continue their mission among cascades of burning phosphorus.
Having used up its lethal cargo, one of the Japanese planes soon dived to follow Lt Savage. To counter the attack he decided to suddenly reduce his engine power. Speeding behind the Hellcat, fast Tojo had no choice but to pass its would-be victim with no time to open fire. A fraction of a second later, the American accelerated again. At full throttle, he was able to stay at the twisting enemy’s tail. The fighter covered with brown-and-silver leveled out his flight low above the ground. Following its every move, the Hellcat spit fire out of six Brownings. Heeding the advice of his armorers, Savage limited his salvoes to four seconds. Longer ones could permanently damage the guns. The stuff he sent after the Japanese plane, was entirely enough. Its fuselage, marked with “meatballs”1  in white squares, couldn’t free itself of the white trails closing in around it. Finally no more fire was necessary. Bullets fired directly from behind disappeared in the Ki-44’s fuselage. Tore through the right wing root, passed through the cockpit. After only a moment the affected areas became full of indistinguishable flames. Smashed along its whole length, the plane’s starboard seemed to be dragging it downward. Just a fraction of a second before the plunge, the canopy flew away. Either shot off or thrown back by the pilot preparing for a jump. The bright, transparent shape passed just above the propeller arc of the pursuing F6F. The next burst didn’t reach the Tojo. Rolling over its wing, the Ki-44 dropped in a slow tail spin, but only rotated twice before crashing into the runway and exploding.
The defeat infuriated Hieto’s defenders even more. This was too much for the Japanese. It seemed to the Americans that AA fire had become omnipresent. Shrapnel cut through the Hellcats more and more densely. A few damaged ones turned towards the aircraft carrier decks. So far all F6F pilots had carried out at least six runs over Hieto. Their tiredness showed. They were running out of ammunition. Fuel was also becoming a problem – there had to be enough left to return. In this situation an encounter with a larger enemy formation couldn’t be risked. Single sections and squadrons began returning to the “Hornet” and “Wasp”. Lt Savage was the last to leave the target area. From a distance, the cameras of his F6F-5P recorded ten columns of black smoke. They came from the burning Japanese wrecks in Hieto. During the return flight, the American went out of his way to carry out a reconnaissance over the neighboring Okoyama airbase. Savage and Dayhoff, who was covering him, made good use of their flight across the airfields. Besides making photographs, they strafed a lot of L2D and Ki-51 transports camouflaged behind the hangars. Seven were declared damaged. At the same moment the fuselage of Dayhoff’s plane was ripped open by a 20-mm shell. The F6F was instantly put out of action. This forced the last two Hellcats to return to the aircraft carrier, on which they landed with almost no fuel left.

The most severe loss suffered in Friday’s operation was only realized by the participants after the last F6F had landed. For some time there was some uncertainty, but LtCdr Schrader would not return. After analyzing the participants’ accounts it was realized that he had been shot down by a stray AA salvo over the Japanese seaplane anchorage.
The last victim of that fateful Friday was Ensign Lee. He and his F6F-5, which had ditched near the “Hornet” just after dark, were never found. The darkness, responsible for the disappearance of Leon Lee, soon engulfed another victim. Lt Helgerson’s F6F-5N, maneuvering on board of the “Hornet”, rolled off its deck. The Hellcat sank immediately and the pilot had no chance of survival. He became one of five people lost by VF-11 on October 13th, 1944. As a compensation for these losses, the squadron reported 19 confirmed aerial victories. Won both in offensive operations and during CAP duties.

Crash on USS “Solomons”. Hellcats from this carrier did not manage to fight over Pacific. [Via Andre R. Zbiegniewski]

Nuts and Bolts
At the beginning of 1936 Leroy Grumman’s aircraft production plant, created six years earlier, moved for good to a location near Bethpage (Long Island). The times were favorable for the development of the company, registered as the Grumman Aircraft Engineering Corporation. The US economy, which had just gotten out of a big crisis, the civil war in Spain, the Italian “pre-emptive strike” in Abyssinia, the re-militarization of Germany…
All those were good reasons for the development of American military technology. The section of the economy neglected for years, especially on the part of the airforce. Grumman’s early products – according to world standards of the time – could not be considered satisfactory, nor mass-produced. The first construction to change all this was the F4F Wildcat.
At the outbreak of the Pacific war, the engineers from Bethpage had already been working for five months on Wildcat’s successor. The new fighter, powered by the same engine as the F4U Corsair, was to be a “reserve project in case of a failure or delay in the Corsair program”. The US Navy BuAer’s faithful decision turned out to be justified. The F4U’s appearance on the decks of American carriers was delayed. During the crucial period of its absence it was duly replaced by engineer Bill Schwendler’s brainchild.
His work on a simple improvement of the Wildcat didn’t seem to lead anywhere at first. It would take more than just a “Wildcat-DeLuxe” to satisfy the customer’s demand. Cosmetic improvements couldn’t change the firepower, range, armor or speed of the F4F. It was necessary to make significant structural changes to achieve all this.
In the dramatic December of 1941, a prototype called “Design No 50” was in its last phase of construction. It was then given designation XF6F-1, in accordance with the US Navy system. The first confrontations of American naval fighters with their Japanese counterparts were not promising at all. Many of Wildcat’s features, such as its rate of climb and maneuverability, were far from satisfactory. In order to allow for the new fighter to use a larger engine than the F4F, it was decided that every part of the plane should be enlarged. Among other things it was hoped this would also increase the new fighter’s endurance. Besides the constructors it was BuAer’s design director, LtCdr. Jackson who played a decisive role in creating the final design. Such features as speed and firepower were to be guaranteed by the new engine. The only difference between the F6F and F4F, visible at first glance was the increased forward visibility. This was achieved by redesign of the engine compartment and its casing. The result – an optimized naval fighter with improved performance, simplified maintenance in field conditions and a sturdy airframe, necessary to withstand rough deck landings and combat damage.

* * *

The F6F Hellcat was a single-seat, single engine mid-winged, all-metal monoplane fighter, with fabric covering only the control surfaces. Its fuselage of semi-monocoque construction, was based on 21 formers and 20 longerons, covered with “flush riveted” aluminum sheeting.
The Hellcat’s oval fuselage consisted primarily of an engine compartment containing a power plant, fuel and oil pumps, a compressor, transmission gear, fire extinguishers, an 83-liter oil tank, and an interstage air and oil cooler with a thermostat regulating the cool air inflow.

Section of F6F-3 from VF-5 division. August of 1943. [Via Andre R. Zbiegniewski]


The engine compartment was closed from the back with a fire-wall connected with the main wing spar. At the same level as the fire-wall, by the rear edges of the engine cover, were located hydraulically powered flaps regulating the airflow.

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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