Grumman G-51 / F7F Tigercat
Still infatuated with developing a more advanced twin-engined fighter to fly off the coming newer and larger carriers the Navy, in early 1941, again called on Grumman to design and build two twin-engine prototypes. The Navy's directive, projected into the future, required that the fighter be powered by powerful 2,100hp (1,566kW) Pratt & Whitney Double Wasps and have a combination of armament consisting of four 20mm cannon and four 0.50 calibre machine-guns. Additionally, the aircraft would carry a torpedo underneath the fuselage or two 1,000 lb (453kg) bombs hung under the wings.
Following the familiar 'Cat' line of aircraft produced for the Navy, Grumman called it the Model G-51 F7F Tigercat. Already proposed by the Navy was the future Midway-class carriers that the F7F would fly off.
In June 1941, Navy officials authorised Grumman to start the G-51 programme and to build two prototypes.
Though the originally planned XF7F-1, naval counterpart of the XP-65, never got off the drawing board, a modified version of it was ordered, to the tune of two prototypes, on 30 June 1941. The new XF7F-1 was much more powerful; indeed it promised to be the most powerful fighter in the world with two 2,000-hp Pratt & Whitney R-2800 Double Wasps (the same engine as used in the F6F). The concept of so powerful a fighter was made practical by the 45,000-ton Midway class carriers, which were being built in 1941. Called the G-51 by Grumman, and allotted the name Tigercat, the XF7F owed much to the earlier twins, the XF5F and XP-50.
Design and construction took nearly 2½ years, up to December 2, 1943. On that day test pilot Bob Hall took off in the prototype XF7F (BuNo 03549) on its maiden flight. Unfortunately, the test programme was delayed somewhat by a non-fatal accident that damaged '549 beyond repair. Luckily by this time the second prototype (03550) was about ready to fly and the test programme continued without let up. The Tigercat's flight data and resultant sterling performance convinced the Navy to immediately order 500 aircraft.
Sitting high off the ground on tricycle landing gear, it had a stubby squared-off wing carrying two huge nacelles for the 2,100-hp R-2800-22W engines. Just ahead of the leading edge, the pilot was surrounded by four 20-mm cannon in the wing roots and four 0.5-in guns in the nose. Under the slim fuselage could be hung a mighty 21.7-in torpedo, and provision was made for two 1,000-lb bombs under the inner wings. This time the wing folds could be simple, a straight up and over with the tips at the same height as the fin. Range, rate of climb and speed (425 mph) all promised to set new levels of performance for carrier-based aircraft.
When the production F7F-1s began coming off assembly lines in quantity in April 1944, Naval strategists decided to operate the Tigercat primarily from land bases due to the length of time to carry out carrier qualification trials at sea. Thus the Tigercat was given to the land-based Marine squadrons who used them as fighter bombers in tactical ground attack operations. The plan turned into an exchange programme whereby 12 USMC squadrons were to be equipped with 'Tigers' while the Marines would give up an equal number of F4U Corsair squadrons and return them to the Navy. The Corsairs then be transferred to Naval squadrons aboard fleet carriers in the Pacific who needed them in the final assault on the Japanese home islands.
By December 1944, Tigercat production suddenly came to a screeching halt owing to the rapidly changing conditions on the battlefront. By the end of 1944 only 35 examples were completed which was blamed on technical problems that unexpectedly cropped up. As the war progressed toward completion in the Pacific, by February 1945, Navy and Marine air squadrons began bombing and strafing targets of opportunity over the home islands; and it called for a change in aerial strategy.
This changed the F7F-1 combat role as previously envisioned by Naval tacticians. This led to the development of a modified night fighter version of the Tigercat. The third production XF7F-1 served as the prototype for the XF7F-2N. The major and most noticeable modification included a second seat for a radar operator located over the mid-point of the wing (a fuel tank being removed to provide room) and a more prominently revised nose to accommodate the radar. This change required the removal of the four machine-guns located under and behind the nose cone but the F7F-2N was still heavily armed, possessing four 20-mm cannon buried in the wing leading edges. Other modifications included rocket launching stubs under the wings and a king-size Tiny Tim 11.75in rocket shackled under the fuselage. For safety reasons, the rocket had to be dropped from the Tigercat before ignition to eliminate the blast that could damage the metal skin. This was accomplished by unwinding a short umbilical cable simultaneously with the rocket which was electronically fired severing the cable.
Since the war's beginning, Pratt & Whitney had been busy developing a more powerful engine to keep pace with the newer, advanced aircraft coming off the assembly lines. The recently completed night-fighter version of the Tigercat became the recipient of the new R-2800-34 giving it a top speed of 445mph (716km/h).
Next phase of the project involved sea trials aboard an aircraft carrier. In April 1945 a select group of Tigercat pilots was temporarily assigned to the USS Antietam and in the ensuing days practised more than 30 night landings. Despite the Tigercats' flawless performances, the Navy strangely let the project die without explanation. The Navy dropped the idea of using twin-engine night fighters on carriers and continued using modified Corsair and Hellcat night fighters that had long proven themselves on fleet carriers.
VMF(N)-533 had the distinction of becoming the first squadron to be equipped with the new Tigercat, arriving in the war zone on August 14, 1945 - ironically the final day of hostilities in the Pacific. The Tigercats were sent up on patrols but they never saw or engaged any enemy air-craft. Shortly after the war ended, the squadron was sent to China where it served for several years with various models of Tigercats. The final conversion of the -3N into the F7F-4 incorporated strengthening of the landing gear and airframe, advanced radar, and arresting gear required for carrier landings. Aware of the fast-changing air environment in the postwar era with the new jet designs coming on-line, the Navy built only 12 -4Ns before closing down the Tigercat line.
In 1950 when the Korean War exploded on the world scene, two Tiger-equipped Marine squadrons, VMF-513 and 542, left the US for the battle zone. Soon after arriving, an F7F-3N fighter piloted by Major E A Crundy shot down an obsolete Polikarpov PO-2 Mule biplane of the Korean Air Force. During the course of the war, only one other PO-2 was downed by a Tigercat. Despite the Tigercat's superlative performance, it was usually sent on such missions rather than tangle with the newly introduced Russian MiG-15 fighter.
Unfortunately, the Tigercat had been designed to fight in a different kind of war. It became the victim of the sudden arrival of the jet era that ended the reign of piston-powered aircraft. Unusual for many World War Two fighters, no Tigercats were sold to foreign countries except two -2Ns that were delivered to the UK for evaluation.
Production of the Tigercat continued throughout 1945 and into November 1946 when it was ended for good. During this time a day fighter version emerged as the F7F-3 powered by Pratt & Whitney R-2800-34Ws. This variant attained the distinction of being the most prolific - 250 were built, all of them between March and June 1946 when production ceased.
The Navy's interest in turning the Tigercat into a night-fighter persisted, hence it called on Lockheed Air Service whose long experience was well known for modifying other company's aircraft to convert 60 F7F-3s into the F7F-3N night version. The single most identifying feature of the -3 was its redesigned fin that blended smoothly into the fuselage required because of the more powerful engine. Most of the fighter variants retained the second cockpit and the enlarged nose containing the SCR-720 radar as on the original -2N.
Other conversions appeared in the field such as the two-seat F7F-2D drone controller and the F7F-P photo-reconnaissance modification with several camera locations.
The Navy broke new ground with the Tigercat because it was the first operational tricycle landing gear aircraft in their inventory. All other Navy and Marine aircraft during World War Two were traditional 'tail draggers'. The unique landing gear configuration made ground handling a breeze and greatly expanded the pilot's forward vision over the nose. Pilots, particularly those above average stature, found the cockpit roomy and comfortable; that coupled with an autopilot and twin-engine safety, greatly eased fatigue on long over-water missions. The cockpit layout and instrumentation was similar to the F6F Hellcat and the F4U Corsair, except for the engine controls and the twin set of instruments.
Although too late for World War II, the Tigercat did see action in Korea, VMF(N)-542’s F7F-3Ns entering combat in October 1950 and performing both day and night in the interdiction task.
The XF7F-1 Tigercat was Gordon Israel's happiest achievement. Even during the beginning of the jet age, the big twin was one of the Navy's best-performing airplanes. With 5,600 horsepower on hand with water injec-tion, the Tigercat was a climbing fool. The airplane also had a remarkable range that made a 2,600-mile cross-country hop - literally across the country - routine for the Navy units equipped with the Tigercat.
The airplane never fired a shot in World War II, but it served in an attack role in Korea. One F7F made it into legend when it came home dragging two 500-pound chunks of concrete attached to cable the North Koreans had rigged as a kind of homemade antiaircraft measure. If the F7F had one drawback, it was the Vmc of 160 knots. Proper takeoff technique called for the pilot to wait for 160 before pulling the gear.
Grumman built but 363 F7Fs of all types. In the postwar period, it served with the Marines and Naval Reserve until the late 1950s. In civil life, the Tigercat's versatility showed up well as an air tanker to fight forest fires or as an agricultural sprayer.
A total of 45 F7F-2Ns was built. Grumman built only 34 F7F-1 single-seat day fighter/attack air-craft, followed by 66 two-seat F7F-2N night-fighters with radar replacing the nose guns, 190 F7F-3 single-seaters with uprated engines, a taller fin and more fuel, 60 F7F-3Ns with two seats and a very long radar nose, and finally 12 F7F-4Ns with full carrier equip-ment and a revised radar nose and second cockpit. The next version to appear was the F7F-3. Some 189 were built, a few being fitted converted with cameras by Lockheed Air Service for reconnaissance as the F7F-3P, whilst 60 two-seat F6F-3N night-fighters were also completed before production came to a close in November 1946 with 13 F7F-4N aircraft featuring an enlarged vertical tail, improved radar and other refinements.
The F7F-3N version was still used in small numbers by the U.S. Marine Corps in 1955.
Engine: Pratt & Whitney R-2800-22W Double Wasp, 2000 hp.
Wingspan: 51 ft
Length: 45 ft
Speed: 427 mph
Range: 1170 miles
Armament: 4 x 20mm cannon
Bombload: 2 x 1000lb bomb or 1 x torpedo
Engine: Pratt & Whitney R-2800-22W Double Wasp, 2000 hp.
Engines: two 2,100-hp (1566-kW) Pratt & Whitney R-2800-34W radial piston engines.
Maximum speed: 700 km/h (435 mph) at 6705 m (22,000 ft)
Service ceiling 12405 m (40,700 ft)
Range 1931 km (1,200 miles)
Empty weight 7380 kg (16,270 lb)
Maximum take-off 11667 kg (25,720 lb)
Wing span 15.70 m (51 ft 6 in)
Length 13.83 m(45 ft 4.5 in)
Height 5.05 m(16 ft7 in)
Wing area 42.27 sq.m (455 sq ft).
Armament: four 12.7-mm (0.5-in) machine-guns and four 20-mm cannon.
Vmc: 130 to 140 kts (149 to 161 mph or 239 to 259km/h).
TO speed: 75 kt, 53in, 2,800rpm.
ROC: 3500 fpm @ 150 mph.
Ldg Gear extension speed: 100 mph.
Max X-wind: 30 mph.
two seat night fighter
Engines: two 2,100 hp Pratt & Whitney R2800-22
Span: 51 ft. 6 in
Weight: 13,000 lb
Range: over 1,500 miles
Max Speed: 425 mph
Engine: Pratt & Whitney R-2800-10W Double Wasp, 2200 hp.