Armoured Aircraft Carriers in World War II

OVERVIEW

With the outbreak of war, the fledgling Fleet Air Arm - barely two years in operation after finally restoring its independence from the Royal Air Force - found itself woefully unprepared.

An emergency order for navalised versions of the old RAF Gladiator was only just being filled. These aircraft, while fine fighters, were no match for the modern types being fielded by the Luftwaffe.

Nor were they expected to engage them.

The Sea Gladiators were ordered to fill a vital role in fighter familiarisation and training for FAA pilots, providing necessary hours of experience in single-seat aircraft. The Sea Gladiator was not intended to be the FAA's primary seaborne fighter. Instead, the idea was for it to free up Skuas and Roc's by taking over the role of base and harbour defence.

A handful did go to sea aboard HMS Glorious off Norway in 1940. Elsewhere, those Sea Gladiators that did end up aboard carriers in a combat role did so as emergency requisitions, not planned air group units.

That they were ever intended to do so is just one of the many derogatory myths that have grown up around the FAA post war.

But the weakness of the Skua and Roc was no myth. And the FAA knew this long before the war started. The Fairey Fulmar emergency program fleet fighter was the outcome of this knowledge, but it would be nine months before the escort fighter would be ready for squadron service.

And the FAA knew it needed more aircraft than Fairey could provide. 

Before there was Lend-Lease there were the undelivered orders placed by France and Greece for US fighter aircraft. The prospect of a diversion of these US-made single-seat naval fighters to the RNwas cause for excitement.

In 1940 the FAA got its hands on a number of Belgian B-339s after the fall of that country to Germany. This export version of the F2A 'Buffalo' proved to be a disappointment when evaluated at RN Air Station Hatston in July 1940: Once vital pilot armour was fitted, its performance and maneuverability deteriorated significantly. Its best speed was 270mph at 6000ft.

FAA Observer David Brown wrote that 804 Squadron FAA pilots assigned to test the Buffalo announced they'd rather continue flying Sea Gladiator biplanes. Any suggestion of placing a production order with Brewster was quietly dropped.

The Wildcat

The Grumman XF4F-1 biplane was a progressive development of the F2F and F3F which equipped the USN during the late 1930s and first years of the 1940s. This 1935 project proved to be a false start, but in 1936 Grumman was issued a contract for a new prototype.

The XF4F-2 was something of an urgent response to competing Brewster’s XF2A-1 “Buffalo” design. The airframe was adapted to that of a mid-winged monoplane with two fuselage-mounted .30 (7.62mm) Browning M2 machine guns firing through the propeller. It also had the capacity to have a further two such guns fitted in the wings, along with wing fittings for 100lbs (45kg) bomblets.

The prototype F4F-2 was flown in September 1937, but the program encountered a string of problems. Repeated crankshaft bearing failures forced the manufacturing process to be changed.

Then, in February 1938, a test-bed caught fire in flight. The pilot was fortunate to have put down before the fuselage failed.

USN compatibility trials were conducted in April 1938 but suffered a setback when an F4F-2’s engine failed during a catapult launch. The subsequent crash required two weeks of work to repair.

Despite promising a top speed of 290mph, there were doubts expressed about the aircraft’s actual performance. Concerns with about the Wildcat's problems including bearing failures caused Grumman to lose the contract for 54 production USN fighters to Brewster’s F2A-1 Buffalo.

But the USN was enticed enough by further promises of improved performance and reliability. Grumman said a new engine of increased horsepower would revive the F4F airframe. The USN issued a contract for another development project, the XF4F-3, in October 1938 as a “hedge” against the Buffalo’s performance.

F4F-3 Production

The prototype XF4F-3 was assembled out of parts salvaged from a pranged XF4F-2 and flew for the first time in February 1939. It had a 1200hp Pratt & Whitney R-1830-76 radial engine with a two-stage, two-speed supercharger offering 150hp more than the XF4F-2. It also had its wing area increased from 232 square feet to 260 sq ft, and the tail surface was also slightly enlarged.

Factory performance figures for the F4F-3 were 331mph at 22,000ft with a service ceiling of 37,000ft. It carried 147 gallons (556litres) of fuel for a range of 860 miles (1284km). The engine, however, was to experience persistent cooling problems. As a result there were many cowling, cowl and propeller spinner modifications during the type's service life in an attempt to improve temperature control.

It had taken almost three years of development, testing and modification before, in August 1939, the USN ordered an initial 54-machine delivery of F4F-3s.

The first production aircraft flew in February 1940, Grumman having gambled on the order being placed by initiating construction of several aircraft before the contract was signed.

The main difference between production and prototype machines was the deletion of the cowling-based .303 machineguns. Instead, the standard armament would be four .50cal (12.7mm) Browning M2 machineguns fitted in the wings. Each gun carried 430 rounds.

France was the first nation to see the potential of the Wildcat, placing an order for 91 in in late 1939 (10 of which were to be provided disassembled for spare parts).

Their export variant differed in that it has a 1200hp Wright R-1820-G205A Cyclone nine-cylinder, single-row radial engine with a single-stage two-speed supercharger. It was also to be fitted with a single 7.5mm Darne MG in each wing with a further two in the engine cowling, along with French radios and gun sights.

US deployment

At the outbreak of war in Europe, the principal fighter being operated from US carriers was the Grumman F3F biplane.

It was a very successful USN fighter, delivered in three sub-variant groups between 1935 and 1938. By late 1938, all US Navy and Marine Corps front-line squadrons were flying Grumman’s F2F-1 and F3F.

The first operational squadron to receive the F4F-3 was Fighting Squadron Four (later designated VF-41) in December 1940. This 18-strong unit was assigned to USS Ranger which was tasked with at-sea assessment of the new type.

The second unit of 20 machines, VF-72, went active in January 1941. It was assigned to USS Wasp. A further group of 10 was delivered to VF-72 later in the year.

These ships undertook shakedown cruises to Guantanamo during which the F4F-3's windscreen issues became apparent, along with fuel pressurization problems at altitude and several spontaneous deployments - one fatal - of the emergency wing flotation bags.

USN deliveries were halted early in 1941 as production lines focused on assembling some 60 F4F-3As for Greece. Nevertheless, some 88 aircraft were completed for the USN between July and September 1941.

By December 31, 1941, a total of 176 F4F-3s had been delivered to USN and Marine squadrons. This included VF-5, VF-8, VF-41, VF-42, VF-71, VF-72, VMF-121 and VMF-211. VF-3 and VF-6 had small numbers assigned.

Letter from Chief of Naval Operations, United States Navy to Head of British Admiralty Delegation, Washington

[CAB 122/ 142] 9 October 1941

Supply of Grumman Martlet fighters

Your letter of 24 September, 1941, concerning the allocation of Grumman single seater fighters and the enclosed memorandum by the Joint Staff Mission have been given thorough consideration. We are in complete agreement as to the necessity for providing single seater fighters for aircraft carriers . United States carriers have always been so equipped. As yet the United States Navy has no folding wing fighters in service. Their production is being delayed by shortages of machine tools and materials due to the high priority given production of other defense materials. Our own carrier fighter squadrons, which we must maintain in readiness for action , are now operating on a very slender margin insofar as reserve aircraft are concerned. Under present schedules we shall continue to have difficulty until late 1942 in providing operating aircraft plus 33– 1/ 3% spares to care for attrition of all sorts. Any diversions or any heavy losses would place us in a very grave situation. The 240 folding wing fighters now scheduled for delivery to you will, in the opinion of the Navy Department, suffice for the needs in the near future of the four carriers which you list as requiring them. This number will provide for each carrier 60 aircraft with which to maintain a strength of 12, a total reserve of 400%, which should be ample to provide both for replacements and training. If fixed wing fighters are used for shore training, the need for the folding wing type will be somewhat decreased...
Because of the very slender reserve on which our carrier fighters are now operating, and the relatively ample reserve for immediate needs afforded you by the present schedule , I cannot agree to the diversion of 100 additional folding-wing fighters from the United States Navy to the British Navy proposed to be made during the period November 1941 – March 1942.

Day of infamy

By December 7, 1941, only one of the three carriers in the US Pacific Fleet had a fully equipped and worked-up squadron of F4F-3As: The USS Enterprise with VF-6.

VF-3 was with USS Saratoga in San Diego and undergoing the working-up process. Lexington was operating the F1A Brewster Buffalo equipped VF-2.

Regardless, the Wildcat program turned out to be a case of just enough, just in time.

Only six months earlier the primary fleet fighter in the USN remained the F3F biplane. But it would be the F4F-3 which would bear the brunt of combat during the first six months of the war against Japan.

While it proved largely out-matched by the nimble A6M “Zero”, at least until an example of that fighter was captured and its limitations assessed, its performance was desperately needed at sea and the tubby little Wildcats gave a good accounting of themselves.

As Scott McCuskey (who scored 6 1/3 victories in F4Fs plus seven in the Hellcat) explained:

"... it was simply a question of flying your aircraft to maximize its advantages and minimize its weaknesses."

Another US pilot commented:

"Unless you tried to fight a Japanese fighter on his own terms or did something stupid, you were not at a real disadvantage in the Wildcat. He could climb away from you, but you could dive away from him. In the F4F, we were not going to score a kill in every fight, but we never felt that we were at a disadvantage where we were going to lose."

Letter from Chief of Naval Operations, United States Navy ... (continued)

Since receipt of your letter, and in the light of our appreciation of both our needs and yours for additional carrier fighters , a study has been made to determine the possibility of increasing the output of folding wing fighters. It appears probable that the output of the Grumman Aircraft Company can be increased, provided that necessary priorities can be obtained for the construction of additional facilities, for the assignment of essential machine tools, and for the allocation of sufficient material. At such time as an increased output is assured, consideration will be given to readjustment of delivery schedules to provide more adequately for the needs of the British Navy. Our review of this situation has shown conclusively that if conditions arise in which numbers of carriers are operated against active opposition, the total capacity now planned for producing carrier fighters will be inadequate. In addition to such remedial action as we may take, it appears imperative that some part of the large British production of fighters should be devoted continuously to a type suitable for carrier use. One of the obstacles to increased carrier fighter production is the emphasis and high priority heretofore given to four- engined bomber requirements. The four -engined bomber program is at least partially responsible for recent delays in the production of Grumman fighters, and may have further adverse effect as the program absorbs a larger proportion of the available machine tools, material and equipment.

Against the wind

But the harsh reality was the Wildcat was easily outmaneuvered and out-climbed by the Zero and other Japanese fighters. It's range, while good by FAA standards, also proved generally inadequate for extended Pacific operations.

A series of problems were also experienced with early F4F-3s in operational service: The wing-mounted flotation bags had a terrifying tendency to deploy without command, and segments of the windshield had a tendency to fail during high-speed dives. Tinkering with the cowling and spinner continued in an effort to address engine overheating.

Provision for a 42 gallon (159litre) non-jettisonable fuel tanks under the wings was also added to improve the tubby little fighter’s endurance.

By 1942 the realities of USN combat had validated the FAA’s earlier fears: Lack of pilot armour was therefore addressed with new plating in the cockpit and around parts of the engine, and bullet-proof glass added to the canopy. Self-sealing fuel bladders were also installed.

But with each new fix came extra weight. This, in turn, degraded performance.

In the meantime, the Royal Navy had delayed deliveries as it waited for production of a Martlet with folding wings.

The USN recognised the sense of such a feature, also changed its F4F-3 production contract to include the provision of hydraulically folding wings. This became the F4F-4.

Folding 'Cats'

Developing a folding wing took Grumman an unexpectedly long time. Eventually the ‘sto-wing’ was designed to rotated some 90 degrees and folded after parallel with the fuselage. In its folded configuration, the F4F-4 had a span of only 14 feet 4 inches (4.4m). Deployed, the wing spanned 38 feet (11.5m).

The USN also wanted a heavier armament: The new F4F-4 model was to carry six .05 caliber MGs in the wings. But the extra weight of the guns came with a price - only 240 rounds per gun could be stowed.

The prototype F4F-4 was completed in April 1941. The consequences of the folding wing conversion were immediately apparent: The Wildcat’s weight had bloated from 7065lb (3205kg) to 7750lb (3515).

The decision was taken to delete the hydraulics from the folding mechanism to bring the F4F-4’s weight back down to a somewhat more acceptable 7489lbs (3397kg).

Performance naturally suffered significantly. This was noted in sea trials aboard USS Saratoga between December 1941 and January 1942.

Factory performance figures for the F4F-4 were reported as 318mph at 19,400ft with a service ceiling of 33,700ft (10,272m). Range was 1275 miles (2052km).

Active squadron service performance figures were below this, however.

Minute from First Lord of Admiralty to Prime Minister

[AVIA 46/ 136] 6 December 1941

Supply of Grumman Martlet fighters

FIGHTER AIRCRAFT FOR THE FLEET AIR ARM.

I am increasingly anxious as regards the prospective situation of shipborne fighter aircraft. I attach a chart on which graphs show how the aircraft available fail to meet the requirements. It will be seen from the graphs that up to the end of 1942 the situation is apparently satisfactory, but I would point out that this apparently satisfactory position is due to the use of the obsolescent Fulmar in the first line squadrons aided by Carriers, and by the prospective supply of 200 Spitfires, which you yourself were instrumental in obtaining for us from the Royal Air Force subsequent to your visit to H.M.S. INDOMITABLE. It was hoped that with the supply of Martlets from the United States of America commencing at the rate of 20 per month, as it should have done from October, 1940, we could have kept our heads above water until the new fleet fighters, Firebrand and Firefly, came into effective production. Owing to the failure of the U.S.A. to keep their promise, the situation deteriorates to a marked degree after the end of 1942. We wish to increase the number of Auxiliary Carriers by a total of 15 in 1942, and are considering a further 15 in 1943 and 1944. This will accentuate our difficulty, because although at present the idea of using these Carriers for anti-submarine purposes is predominant, it may well be that Germany will push out her air-raiders to an extent which will require Auxiliary Carriers to be equipped with fighters in addition to anti-submarine craft... It is clear, therefore, that unless drastic steps are taken to increase the production of fleet fighters, we are likely to be in a nasty hole from the beginning of 1943 onwards...

The American folding fleet fighter is the ideal aircraft for the job, but here again the productive capacity of the United States is barely sufficient to meet the requirements of their own Navy, which is much behind in modern aircraft owing to the fact that Congress has not allowed them to change their aircraft more than once every five years. During Admiral Lyster’s visit to the United States it was emphasised to him by Col . Knox, Admiral Stark and other high officials in the U.S . Navy and elsewhere, thatin order to meet the requirements of both the Royal Navy and the United States Navy means must be found:–

(a) to increase the present rate of production of naval aircraft and

(b) to increase the productive capacity for naval aircraft.

As far as (a) is concerned, steps have been taken to increase the output of the Grumman factory from 60 to 75 fighters per month. Of this the Royal Navy will be receiving aircraft at the rate of 25 per month from April, 1942. This is only a target figure and experience has shown that target figures are never reached and we shall be lucky if we get 75% of the target.

Safety in numbers

The USN ordered 436 F4F-4s June 1941. The first eight deliveries went to VF-6 aboard USS Enterprise in March 1942. By the time of the Doolittle Raid (April 18), Enterprise was carrying 22 F4F-4s and five F4F-3s. VF-8 aboard USS Hornet had 30 F4F-4s.

The F4F-4 was blooded for the USN at Midway on June 4-7, 1942. Enterprise, Hornet and Yorktown each carried 27 F4F-4s at this time.

But, early in 1942 the need for a successor to the Wildcat was already obvious. Grumman resolved to cease production in favour of its new F6F-3 Hellcat.

Nevertheless, there was still demand for the Wildcat - particularly for deployment aboard the growing numbers of escort carriers rolling off the slipways. The F4F’s small size was its advantage, and its performance relative to the opposition it was expected to encounter in escort duties remained acceptable.

In April 1942, the contract to build 839 “FM-1” Wildcats (lease redesignation for F4F-4s) for the USN and 311 “Martlet V’s” for the FAA was awarded to General Motors’ Eastern Aircraft Division.

The FM-1 quickly dropped its armament from six .50 cal MGs to four with increased ammunition capacity (430rpg) in response to complaints from pilots that their weight was making the fighter sluggish and that firing time was insufficient.

Production of the FM-2 variant began in the second half of 1943. These were fitted with 1350hp Wright R-1829056 Cyclone engines. These carried nine cylinders, were air cooled and had a single-stage, two speed supercharger. It was some 500lbs (227kg) lighter than previous Wildcat powerplants, giving it a factory specified top speed of 320mph at 28,000ft, with a service ceiling of 35,600ft. It had a range of 1350 miles (2173km).

Another notable difference in the FM-2 was its ability to carry zero-length rocket launchers and two 58gal (220litre) drop tanks under each wing.

In all 4437 were built for the USN and a further 340 assigned to the RN as the Wildcat VI (The designation “Martlet” had been by this time dropped.

Wildcat production was ceased in April 1945.

Note by Joint Secretaries... (continued)

Owing to a delay of over 9 months in the appearance of the folding wing Martlet, and to increased commitments involved in the new measures to counter the air menace in the Battle of the Atlantic, the Navy have been forced to obtain obsolescent R.A.F. fighter aircraft for use in the few carriers with large lifts. By next spring the first line strength of single-seater fighters necessary to fill carriers to complement will amount to 120 (10 squadrons, say); five squadrons, but no more, can be maintained by the fighters diverted to the Navy by the R.A.F. It is not possible to use R.A.F . fighters for more than five squadrons for the following reasons:

(1) the aircraft will not be available.

(2) non -folding aircraft cannot be used in the remaining single-seater fighter squadrons. We are faced with the difficulty of providing the remaining five squadrons.

The only British naval single-seater fighter is the Firebrand, a machine which is to be produced ‘off the board’ with deliveries commencing at a very slow rate early next summer. Because of limited capacity, the peak target monthly delivery rate of the Firebrand is only 25, this peak being planned to be attained in October 1942. Allowing for inevitable delays and difficulties encountered in the introduction of a new type of aircraft into service, it is thought that the first operational squadron of Firebrand fighters will only be formed at the outset of 1943. The latter epoch coincides with the time of the proposed formation of new squadrons for the INDEFATIGABLE: six months later new squadrons are required for the IMPLACABLE.

The above statements relating to the Firebrand make it plain that IF THE CARRIERS ILLUSTRIOUS , FORMIDABLE, VICTORIOUS , AND ARK ROYAL ARE NOT TO BE ENTIRELY DEPRIVED OF FIGHTER PROTECTION, IT WILL BE IMPERATIVE TO FORM AT LEAST 5 FIRST LINE MARTLET SQUADRONS AND TO MAINTAIN THEM UNTIL AT LEAST HALF WAY THROUGH 1943.

Since losses on these five squadrons and on the two squadrons of training aircraft are budgeted to amount to about 15 a month and since it has been found essential to build up reserve pools of naval aircraft, it is at once obvious that FAILURE OF THE U.S.A. TO DELIVER THE 20 (FOLDING WING ) MARTLETS A MONTH ASKED FOR AFTER THE PRESENT ORDER FOR 240 COMPLETES IN AUGUST, 1942, WILL RESULT IN THE EXPOSURE OF FOUR IMPORTANT CARRIERS TO GRAVE RISKS OR IN THE IMMOBILIZATION OF IMPORTANT NAVAL RESOURCES.

Owing to the introduction of new type of two-seater fleet fighter, the Firefly, towards the end of 1943, and the previous cessation of production of the Fulmar, the two-seater fighter situation during the last few months of 1942 and the first months of 1943 will probably be very ‘tight’. The arming of the ILLUSTRIOUS, FORMIDABLE, VICTORIOUS, and the ARK ROYAL with two-seaters in lieu of single-seaters does not therefore exist as a possibility. It will therefore be seen that the release of a continuation order of 20 Martlets a month is a matter of the highest priority towards the Navy war effort …