The Grumman F4F Wildcat is an American carrier-based fighter aircraft that began service in 1940 with the United States Navy, and the British Royal Navy where it was initially known as the Martlet.
First used by the British in the North Atlantic, the Wildcat was the only effective fighter available to the United States Navy and Marine Corps in the Pacific Theatre during the early part of the Second World War.
U.S. Navy Wildcats
The original Grumman F4F-1 design was a biplane, which proved inferior to rival designs, necessitating a complete redesign as a monoplane named the F4F-2.
This design was still not competitive with the Brewster F2A Buffalo which won initial U.S. Navy orders, but when the F4F-3 development was fitted with a more powerful version of the engine, a Pratt & Whitney Twin Wasp R-1830-76, featuring a two-stage supercharger, it showed its true potential.
U.S. Navy orders followed as did some (with Wright Cyclone engines) from France; these ended up with the Royal Navy’s Fleet Air Arm after the fall of France and entered service on 8 September 1940.
These aircraft, designated by Grumman as G-36A, had a different cowling from other earlier F4Fs and fixed wings, and were intended to be fitted with French armament and avionics following delivery.
In British service initially, the aircraft were known as the Martlet I, but not all Martlets would be to exactly the same specifications as U.S. Navy aircraft.
The F4F-3S Wildcatfish, a floatplane version of the F4F-3.
Edo Aircraft fitted one F4F-3 with twin floats.
This floatplane version of the F4F-3 was developed for use at forward island bases in the Pacific, before the construction of airfields.
It was inspired by appearance of the A6M2-N “Rufe”, a modification of the Mitsubishi A6M2 “Zeke”. BuNo 4038 was modified to become the F4F-3S “Wildcatfish”.
Twin floats, manufactured by Edo Aircraft Corporation, were fitted.
To restore the stability, small auxiliary fins were added to the tail plane.
Because this was still insufficient, a ventral fin was added later.
The F4F-3S was first flown 28 February 1943.
The weight and drag of the floats reduced the maximum speed to 241 mph (388 km/h).
As the performance of the basic F4F-3 was already below that of the Zero, the F4F-3S was clearly of limited usefulness.
In any case, the construction of the airfields at forward bases by the “Seabees” was surprisingly quick.
Only one was converted.
One of the main features of the F4F-4 were the Sto-Wing-design folding wings, a Grumman patented design
A new version, the F4F-4, entered service in 1941 with six machine guns and the Grumman-patented Sto-Wing folding wing system, which allowed more aircraft to be stored on an aircraft carrier, increasing the number of fighters that could be parked on a surface by more than a factor of 2.
This version was less popular with American pilots because the same amount of ammunition was spread over two additional guns, decreasing firing time.
With the F4F-3’s four .50 in (12.7 mm) guns and 450 rpg, pilots had 34 seconds of firing time; six guns decreased ammunition to 240 rpg, which could be expended in less than 20 seconds.
The increase to six guns was attributed to the Royal Navy, who wanted greater firepower to deal with German and Italian foes.
Extra guns and folding wings meant extra weight, and reduced performance: the F4F-4 was capable of only about 318 mph (512 km/h) at 19,400 ft (5,900 m).
Rate of climb was noticeably worse in the F4F-4; while Grumman optimistically claimed the F4F-4 could climb at a modest 1,950 ft (590 m) per minute, in combat conditions, pilots found their F4F-4s capable of ascending at only 500 to 1,000 ft (150 to 300 m) per minute.
Moreover, the F4F-4’s folding wing was intended to allow five F4F-4s to be stowed in the space required by two F4F-3s.
In practice, the folding wings allowed an increase of about 50% in the number of Wildcats carried aboard U.S. fleet aircraft carriers.
A variant of the F4F-4, designated F4F-4B for contractual purposes, was supplied to the British with a modified cowling and Wright Cyclone engine.
These aircraft received the designation of Martlet IV.
Two F4F-3s (the 3rd and 4th production aircraft, BuNo 1846/1847) were fitted with a Wright R-1820-40 engine and designated XF4F-5.
General Motors / Eastern Aircraft produced 5,280 FM variants of the Wildcat.
Grumman’s Wildcat production ceased in early 1943 to make way for the newer F6F Hellcat, but General Motors continued producing Wildcats for both U.S. Navy and Fleet Air Arm use.
Late in the war, the Wildcat was obsolescent as a front line fighter compared to the faster (380 mph/610 km/h) F6F Hellcat or much faster (446 mph/718 km/h) F4U Corsair.
However, they were adequate for small escort carriers against submarine and shore threats.
These relatively modest ships only carried two types of aircraft, the Wildcats and GM-built TBM Avengers.
The Wildcat’s lower landing speed and ability to take off without a catapult made it more suitable for shorter flight decks.
At first, GM produced the FM-1, identical to the F4F-4, but reduced the number of guns to four, and added wing racks for two 250 lb (110 kg) bombs or six rockets.
Production later switched to the improved FM-2 (based on Grumman’s XF4F-8 prototype) optimized for small-carrier operations, with a more powerful engine (the 1,350 hp (1,010 kW) Wright R-1820-56), and a taller tail to cope with the torque.
The F4F-7 was a photoreconnaissance variant, with armor and armament removed.
It had non-folding “wet” wings that carried an additional 555 gal (2,101 L) of fuel for a total of about 700 gal (2,650 L), increasing its range to 3,700 mi (5,955 km).
A total of 21 were built.
The F2M-1 was a planned development of the FM-1 by General Motors / Eastern Aircraft to be powered by the improved XR-1820-70 engine, but the project was cancelled before any aircraft were built.
Royal Navy Martlets
Martlet Mk I
At the end of 1939, Grumman received a French order for 81 aircraft of model G-36A, to equip their new Joffre-class aircraft carriers: Joffre and Painlevé.
The main difference with the basic model G-36 was due to the unavailability for export of the two-stage supercharged engine of F4F-3.
The G-36A was powered by the nine-cylinder, single-row Wright R-1820-G205A radial engine, of 1,200 hp (890 kW) and with a single-stage two-speed supercharger.
The G-36A also had French instruments (with metric calibration), radio and gun sight.
The throttle was modified to conform to French pre-war practice: the throttle lever was moved towards the pilot (i.e. backward) to increase engine power.
The armament which was to be fitted in France was six 7.5 mm (.296 in) Darne machine guns (two in the fuselage and four in the wings).
The first G-36A was flown on 11 May 1940.
After France’s defeat in the Battle of France, all contracts were taken over by Britain.
The throttle was modified again, four 0.50 in (12.7 mm) guns were installed in the wings and most traces of the original ownership removed.
The Martlets were modified for British use by Blackburn, which continued to do this for all later marks.
British gunsights, catapult spools and other items were installed.
After attempts to fit British radio sets, it was decided to use the superior American equipment.
The first Martlets entered British service in August 1940, with 804 Naval Air Squadron, stationed at Hatston in the Orkney Islands.
The Martlet Mk I did not have a wing folding mechanism and was therefore used primarily from land bases, with the notable exception of six aircraft of 882 Sqn aboard Illustrious from March 1942.
In April 1942 Illustrious transferred two Martlet I aircraft to HMS Archer while in port at Freetown.
One of her four retained Martlet I aircraft were subsequently fitted with folding wings by ship’s staff during passage to Durban.
In 1940, Belgium also placed an order for at least 10 Martlet Mk 1s.
These were to be modified with the removal of the tail hook.
Belgium surrendered before any aircraft were delivered and by 10 May 1940, the aircraft order was transferred to the Royal Navy.
Martlet Mk II
Before the Fleet Air Arm took on charge the Martlet Mk Is, it had already ordered 100 G-36B fighters.
The British chose the Pratt & Whitney R-1830-S3C4-G engine to power this aircraft; this too had a single-stage, two-speed supercharger.
The FAA decided to accept a delay in delivery to get Martlets fitted out with the Grumman-designed and patented Sto-Wing folding wing system first fitted onto U.S. Navy F4F-4 Wildcats, which were vitally important if the Martlet was to be used from the first 3 Illustrious class carriers which had elevators that were too narrow to accommodate non-folding wing aircraft.
Martlet Mk III
The first 30 F4F-3As were released for sale to Greece, after the Italian invasion in November 1940.
However, at the defeat of Greece in April 1941 the aircraft had only reached Gibraltar.
They were taken over by the FAA as Martlet Mk III(B).
As these aircraft did not have folding wings, they were only used from land bases.
Martlet Mk IV
The Royal Navy purchased 220 F4F-4s adapted to British requirements.
The main difference was the use of a Wright R-1820-40B Cyclone in a distinctly more rounded and compact cowling, with a single double-wide flap on each side of the rear and no lip intake.
Martlet Mk V
The Fleet Air Arm purchased 312 FM-1s, originally with the designation of Martlet V.
In January 1944, a decision was made to retain the American names for US-supplied aircraft, redesignating the batch as the Wildcat V.
Wildcat Mk VI
The Wildcat VI was the Air Ministry name for the FM-2 Wildcat in FAA service.