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The Grumman F9F Panther / Cougar

v1.0.3 / 01 jul 13 / greg goebel / public domain

* During World War II, the Grumman Aircraft Corporation of Bethpage, New York, became famous for its naval piston-powered combat aircraft -- F4F Wildcat, F6F Hellcat, and TBF Avenger. In the postwar period, Grumman carried on the tradition into the jet age by introducing the "F9F Panther", which performed distinguished service in the Korean War, and which was followed by a swept-wing version, the "Cougar". This document gives a history and description of the Panther and Cougar.

Grumman F9F-2 Panther


[1] F9F ORIGINS / F9F-2 & F9F-3
[2] F9F-2 DESCRIBED / PANTHER IN COMBAT
[3] F9F-4 / F9F-5
[4] GRUMMAN COUGAR
[5] COMMENTS, SOURCES, & REVISION HISTORY

[1] F9F ORIGINS / F9F-2 & F9F-3

* At the end of World War II, most American aircraft manufacturers had designs for jet aircraft on the drawing boards. Following work on several concepts for pure jet and "mixed power" aircraft with both jet and piston propulsion, engineers at the Grumman Corporation considered a two-seat night fighter, the "G-75", something like the company's F7F Tigercat but powered by Westinghouse J30 turbojets. Since this engine provided only a feeble 13.4 kN (1,360 kgp / 3,000 lbf) of thrust, the G-75 had four engines, mounted in the wings.

The G-75 lost the competition to the Douglas XF3D-1, which would emerge as the "Skyknight", but as a backup plan the US Navy Bureau of Aeronautics (BuAer) awarded Grumman a contract for two prototypes of the G-75, with the military designation "XF9F-1", on 11 April 1946. As work on the G-75 progressed it was increasingly obvious that it was a loser, but Grumman had also been working on an entirely different concept for a single-seat day fighter, the "G-79". In an intriguing exercise in bureaucratic paperwork, instead of formally canceling the G-75 program and awarding a new contract for the G-79, the G-75 contract was simply amended to specify the G-79, with three prototypes to be built.

Two of the prototypes, to be designated "XF9F-2", were to be powered by a single Rolls-Royce "Nene" centrifugal-flow turbojet engine, with 22.3 kN (2,270 kgp / 5,000 lbf) thrust and mounted in the fuselage. Efforts were underway at the time to arrange license production of the Nene by Pratt & Whitney (P&W) in the US as the "J42". Since the license arrangement hadn't been finalized, as a backup plan the third G-79 prototype, designated "XF9F-3", was to be powered by a similar but less powerful General Electric / Allison J33 engine, with 20.5 kN (2,090 kgp / 4,600 lbf) thrust.

Grumman XF9F-2

The first XF9F-2 performed its initial flight on 21 November 1947, with Grumman test pilot Corwin H. "Corky" Meyers at the controls. The second prototype flew on 26 November. Both were unarmed. The second prototype crashed during carrier trials on 28 October 1948, but the development program suffered no real delays. The Allison-powered XF9F-3 performed its initial flight on 16 August 1948.

Hedging their bets, Navy brass decided to order both versions of the "Panther", as the new fighter was called, specifying the production of 47 F9F-2s and 54 F9F-3s. The two variants were to be produced in parallel, with the initial production items of both flying in November 1948. However, license construction of the J42 / Nene by P&W was moving forward, rendering the Allison-powered Panther unnecessary, and in fact all the F9F-3s were either completed as or rebuilt to F9F-2 specification.

Initial deliveries of the F9F-2 to service units began in May 1949, and a total of 564 was built, including those that started life as F9F-3s. Underwing stores pylons were added about halfway through production; these Panthers were known using the designation of "F9F-2B" for a time, until all earlier production was refitted with stores pylons, and then all were simply referred to as F9F-2s.

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[2] F9F-2 DESCRIBED / PANTHER IN COMBAT

* The F9F-2 was of all-metal construction, with a mid-mounted straight wing, tricycle landing gear, and a "stinger"-type arresting hook under the exhaust. The wing featured leading-edge and trailing-edge flaps. The tail assembly was of conventional configuration, with a mid-mounted tailplane. There was a small extensible bumper just ahead of the arresting hook. The main gear hinged in the wings to retract towards the fuselage, while the nosewheel retracted backwards. There was a split perforated airbrake just behind the nosewheel doors. The nose and tail pulled off for maintenance.

The F9F-2 was powered by a J42-P-8 turbojet with 22.3 kN (2,270 kgp / 5,000 lbf) dry thrust and 25.6 kN (2,605 kgp / 5,750 lbf) boost thrust with water injection; early production had the J42-P-6 with the same thrust but a different ignition system. The engine intakes were in the wing roots. There were two spring-loaded auxiliary intake doors for takeoff and emergency airflow positioned, somewhat surprisingly, on the spine of the aircraft's midsection.

Grumman F9F-2 Panther

The wings folded hydraulically upward from just outboard the main gear; oddly, the wing fold angle was well short of the vertical. 455 liter (120 US gallon) fuel tanks were permanently mounted on the wingtips. The tip tanks were not fitted originally to the prototypes, being initially trialed on the first prototype and rolled into manufacturing with the 13th production F9F-2. Including internal tanks and wingtip tanks, total fuel capacity was 3,498 liters (923 US gallons). The pilot sat on an ejection seat in a pressurized cockpit under an all-round vision canopy that slid backwards to open. There was a small step on the lower fuselage that could be slid out to help the pilot get into and out of the aircraft.

The F9F-2 was armed with four 20 millimeter M3 Hispano-type cannon with 190 rounds per gun, fitted in the nose. The guns were aimed by a Mark 8 computing optical gunsight. The F9F-2 had no radar. It had four stores pylons under each wing, with a heavy pylon inboard and three lighter pylons outboard, for a total of eight pylons. The large pylon could handle up to a 450 kilogram (1,000 pound) bomb and was "wet", allowing carriage of a 568 liter (150 US gallon) drop tank. The outer wing pylons could each carry up to a 125 kilogram (250 pound) bomb or a 12.7 centimeter (5 inch) "high velocity air rocket (HVAR)"; it doesn't seem that HVARs were ever carried on the large pylon, possibly because they were too close to the intakes and rocket exhaust ingestion might have caused engine stalls. Total external load was 900 kilograms (2,000 pounds) -- though in practice, the F9F-2 was too underpowered to take off from a carrier deck with anything resembling a full combat load. Engine improvements were clearly needed.

Grumman Panther external stores

Although the prototypes had flown in natural metal finish, production machines were painted in overall dark sea blue, the standard US Navy and Marine color scheme of the day. Colorful trim was added as desired by various squadrons.

* The F9F-2 was the first US Navy jet to go into combat, performing airstrikes in support of UN forces fighting in Korea on 3 July 1950. The Panther would score its first "kill" on 3 July 1950, when Ensign E.W. Brown and LTJG L.H. Plog shared credit for the destruction of a Yakovlev Yak-9 piston-powered fighter. On 9 November 1950, Lieutenant Commander Tom Amen claimed the destruction of a Russian-built Mikoyan MiG-15 fighter, the US Navy's first jet-on-jet kill. Panthers would claim four or five more kills against the MiG-15 and records show no losses of Panthers to the MiG-15 in return -- but air combat statistics are notoriously dodgy, and these figures might be taken with a grain of salt.

The Panther was not generally the equal of the faster MiG-15 in performance and was mostly used in the attack role, but like its Grumman ancestors its was extremely rugged, able to both dish out and take punishment. It became the most heavily used jet fighter of the Navy and Marines during in the war. It also became the mount of the US Navy "Blue Angels" flight demonstration team in 1949, replacing Grumman F8F-1 Bearcats and becoming the first jet flown by the Angels.

A number of F9F-2s were field-modified by the Navy to a photo-reconnaissance configuration as a "stopgap solution", seeing service in Korea. These machines had no cannon, the nose carrying a suite of vertical and oblique cameras instead, and were designated "F95-2P". They served through most of the war, operating as a complement to McDonnell F2H-2P Banshee photographic reconnaissance machines.

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[3] F9F-4 / F9F-5

* The Navy liked the F9F-2 enough to obtain improved Panthers. 73 "F9F-4s" with the Allison J33-A-16 turbojet were ordered, with the engine providing 27.8 kN (2,835 kgp / 6,250 lbf) dry thrust and 30.9 kN (3,150 kgp / 6,950 lbf) boost thrust with water injection. The F95-4 also featured:

The F9F-4 prototype was converted from a production F9F-2 and performed its initial flight on 5 July 1950. 109 production F9F-4s were built and the Marines operated at least one squadron in Korea, but the Allison engine was unreliable, and many of these were converted to the "F9F-5" configuration.

* The F9F-5 was effectively an F9F-4 with the stretched fuselage, taller tailfin, and so on, but with an improved derivative of the Nene turbojet, known as the Rolls-Royce "Tay" and built under license by P&W as the "J48", instead of the Allison J33-A-16. The J48-P-6 engine fitted to the F9F-5 provided 27.8 kN (2,835 kgp / 6,250 lbf) dry thrust and 31.1 kN (3,175 kgp / 7,000 lbf) wet thrust. (Some sources hint that the Tay / J48 had afterburning, but this claim is hard to confirm.)

Grumman F9F-5 Panther

The initial prototype F9F-5, a converted production F9F-2, performed its first flight on 21 December 1949, with deliveries to the Navy and Marines beginning in November 1950. The F9F-5 generally replaced the relatively underpowered F9F-2 in service, and went into combat in Korea in late 1952. The Blue Angels had already upgraded to the F9F-5 about a year earlier, in late 1951.

   GRUMMAN F9F-5 PANTHER:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                11.6 meters         38 feet
   wing area               23.2 sq_meters      250 sq_feet
   length                  11.83 meters        38 feet 10 inches
   height                  3.73 meters         12 feet 3 inches

   empty weight            4,600 kilograms     10,150 pounds
   loaded weight           8,500 kilograms     18,720 pounds

   max speed at altitude   1,005 KPH           625 MPH / 545 KT
   service ceiling         13,000 meters       42,650 feet
   range                   2,090 kilometers    1,300 MI / 1,130 NMI
   _____________________   _________________   _______________________

A total of 616 F9F-5s was built, not counting F9F-4 conversions. Some F9F-5s were delivered in anodized aluminum finish as something of an experiment, but the metal didn't hold up against corrosion and Panthers went back to glossy sea blue.

A total of 36 "F9F-5P" unarmed photo-reconnaissance machines was built as well. The cannon were removed and replaced by vertical and oblique cameras. The modified nose stretched the length of the aircraft by 37 centimeters (14.6 inches) to 12.2 meters (40 feet). The F9F-9P also included an autopilot to provide stability during photoshoots.

* The Panther was quickly relegated to Reserve service after the Korean War, lingering on late into the decade. Some Panthers were modified as target drones and designated "F9F-2D" or "F9F-5D" as appropriate, with others modified as drone controllers and designated "F9F-2KD" or "F9F-5KD" as appropriate; the drones remained in service into the early 1960s. The only way to tell them from conventional Panthers was by the presence of a set of blade antennas on the nose. There were a number of other conversions of Panthers:

Panthers were also used for armament trials. A picture survives of an F9F-5 at the naval weapons test center at China Lake in California carrying four pods of four 12.7 centimeter Zuni rockets, for a total warload of 16 rockets -- a formidable punch in the attack role.

Grumman Panther with Zuni rocket pods

* The only foreign user of the Panther was Argentina, which received 24 refurbished F9F-2s in 1958. They were operated by the Argentine Navy from ground bases. Four were destroyed on the ground in a 1963 coup that put the army and navy at odds. The survivors performed border patrols in 1965 during a period of troubles with Chile. All were grounded due to lack of spares in 1969.

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[4] GRUMMAN COUGAR

* At the outset of the F9F program, the Navy had pressed Grumman to consider a swept-wing version, but in the face of inexperience with swept-wing aerodynamics at the time, the company's engineers were uncertain of how to proceed and the swept-wing F9F stayed on the back burner for the time being. The Korean War and the MiG-15 brought it to the front burner, and in March 1951 the US Navy awarded Grumman a contract for a swept-wing F9F, which was given the company model number of "G-93".

Three F9F-5s were modified on the production line as G-93 prototypes, with two of these machines being flight prototypes and the third a static test airframe. The program moved along quickly, the F9F-5 being a mature aircraft and much having been learned about swept wings in the previous few years. The initial flight of the "F9F-6" was on 20 September 1951, with Grumman test pilot Fred C. Rowley at the controls.

Grumman F9F-6 Cougar

The new variant was different enough from the F9F-5 to be given a new name: "Cougar". The Cougar featured a wide range of improvements:

The Cougar retained other elements of the Panther, such as the quad 20 millimeter cannon and J48 engine. Although early Cougar production was fitted with the J48-P-6A variant, which was the same as the J48-P-6 with some fixes, later F9F-6 production featured the J48-P-8, with a max thrust of 32.2 kN (3,290 kgp / 7,250 lbf).

   GRUMMAN F9F-8 COUGAR:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                10.52 meters        34 feet 6 inches
   wing area               31.31 sq_meters     337 sq_feet
   length                  12.73 meters        41 feet 9 inches
   height                  3.73 meters         12 feet 3 inches

   empty weight            5,380 kilograms     11,860 pounds
   loaded weight           11,230 kilograms    24,760 pounds

   max speed at altitude   1,040 KPH           645 MPH / 560 KT
   service ceiling         15,240 meters       50,000 feet
   range                   1,690 kilometers    1,050 MI / 915 NMI
   _____________________   _________________   _______________________

Initial service deliveries were in late 1952. Pilots were delighted with the improved performance of the Cougar, and surprisingly it turned out to have better carrier handling than the Panther. No doubt Navy and Marine pilots were eager to take on MiG-15s with a machine that could fight on more equal terms, but the Cougar didn't reach combat before the war ended in July 1953.

Grumman F9F-6 Cougar

646 F9F-6 Cougars were built into 1954. They were delivered in classic Navy overall sea blue colors, but generally updated to the new standard of gull gray on top and white on the bottom. Many were refitted in service with a UHF direction finder in a fairing under nose, and some were fitted with a nose inflight refueling probe. On 1 April 1954, three probe-equipped F9F-6s set a transcontinental speed record by flying coast-to-coast in under four hours, the best time being 3:45:30 for a distance of 3,925 kilometers (2,438 miles).

* A total of 60 "F9F-6P" unarmed photo-reconnaissance machines with a camera nose and no cannon was built in 1954 and 1955. The camera nose stretched the aircraft by 22 centimeters (9 inches) to 12.86 meters (42 feet 2 inches). Some were refitted with nose inflight refueling probes.

Grumman F9F-6P

They were followed by 168 "F9F-7s" with the Allison J33-A-16A engine. As with the F9F-4, the Allison engine proved unreliable, and 50 of these machines were delivered with the J48 engine, making them indistinguishable from F9F-6s. Most F9F-7s that were delivered with the Allison engine were refitted with the J48 as well.

The final single-seat fighter version of the Cougar, the "F9F-8", was introduced in 1954. It featured a 20 centimeter (8 inch) fuselage stretch with a larger fuselage fuel tank; a reinforced canopy; and a redesigned wing, with greater area and reduced thickness to improve handling and provide more wing fuel tankage. Fuel capacity was increased to a total of 4,029 liters (1,063 US gallons). The F9F-8 was powered by a J48-P-8A or J48-P-8C engine, with the same thrust as the J48-P-8, but with some minor improvements.

A total of 601 F9F-8s was built from 1954 to 1957. Late production was fitted with a nose inflight refueling probe; it appears that earlier production was refitted with the probe as well, and that the F9F-8 was also refitted with the UHF homing system in an undernose fairing. Late production F9F-8s could also carry four Sidewinder air-to-air missiles (AAMs), two under each wing, and some earlier production was refitted with Sidewinder capability as well.

Grumman F9F-8 Cougar

The Blue Angels traded in their F9F-5 Panthers for F9F-8 Cougars in 1954; they had been handed F9F-6s in 1953, but demand for the Cougar at the time was intense and they were promptly yanked to operational service. The Angels flew the F9F-8 up to 1957, when it was replaced with the Grumman F-11F Tiger.

A number of F9F-8s were modified as "F9F-8B" tactical nuclear bombers, fitted with a "Low Altitude Bombing System (LABS)". A total of 110 "F9F-8P" unarmed reconnaissance machines with a swollen "duck's bill" camera nose were built as well. They could be fitted with a nose refueling probe.

Grumman F9F-8P, F9F-8T

The last production version of the Cougar was the "G-105" or "F9F-8T", a tandem-seat trainer. It featured a fuselage stretch of 86.4 centimeters (34 inches) and a single rearward-sliding canopy. There was a windscreen between the cadet pilot's seat in front and the instructor's seat in back; armament was reduced to two cannon. Initial flight of the F9F-8T was on 4 April 1956. The US Navy had planned to adopt a navalized version of the Lockheed T-33 trainer, the "T2V-1 Sea Star", and had initially not been very interested in the F9F-8T. However, the Sea Star program ran into troubles and the F9F-8T began to seem more attractive, with the Navy obtaining a total of 399 F9F-8Ts.

Most F9F-8Ts were refitted with a nose refueling probe and some were wired for Sidewinder AAMs, though in fact they rarely carried them. A night-fighter version with AAM armament was considered but not adopted, and an improved trainer with a P&W J52 turbojet was also considered but rejected.

* The Cougar was regarded as a fine aircraft, very rugged and reliable, with excellent handling. Aircraft design was moving very rapidly in the 1950s, however, and Cougar fighters were out of first-line service by the end of the decade. They lingered in Reserve service into the mid-1960s. After retirement from squadron service, Cougars were used as drones -- including the "F9F-6K", "F9F-6K2", and "F9F-8K" -- and drone directors -- including the "F9F-6D", "F9F-6PD", and "F9F-8D".

The US military services adopted a uniform aircraft designation system in 1962, and such Panthers as were still in operation at the time were redesignated as follows:

   _________________

   F9F-5KD:   DF-9E
   F9F-6:     F-9F
   F9F-6D:    DF-9F
   F9F-6K:    QF-9F
   F9F-6K2:   QF-9G
   F9F-7:     F-9H
   F9F-8:     F-9J
   F9F-8T:    TF-9J
   _________________

The F9F-8T / TF-9J remained in training service into 1974. Four were flown in Vietnam on fast spotter missions. A number of Cougars remain on static display, but it doesn't appear any are flying any longer.

* As with the Panther, a number of Cougars were used for test and trials:

The only foreign user of the Cougar was once again Argentina, which obtained two hand-me-down US Navy F9F-8Ts in 1962. They were withdrawn from service in 1971.

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[5] COMMENTS, SOURCES, & REVISION HISTORY

* The following table gives F9F variants and production:

   variant  built  mods  notes
   ______________________________________________________________________

   XF9F-1       2        Panther prototypes.
   F9F-2      564        Initial production Panther.
   F9F-2B       -        Early designation for F9F-2 with stores pylons.
   F9F-2P       -     ?  Field modifications to reconnaissance spec.
   F9F-2D       -     ?  F9F-2 drone conversions.
   F9F-2KD      -     ?  F9F-2 drone controller conversions.
   XF9F-3       1        F9F prototype with Allison J33 turbojet.
   F9F-3        -        F9Fs built with J33, all completed as F9F-2s.
   F9F-4      109        Production F9Fs with J33, tall tailfin, stretch.
   F9F-5      616        Like F9F-4 but with J48 / Nene engine.
   F9F-5P      36        Unarmed F9F-5 with camera nose.
   F9F-5D       -     ?  F9F-5 drone conversions.
   F9F-5KD      -     ?  F9F-5 drone controller conversions.
   ______________________________________________________________________

            1,328        TOTAL PANTHERS
   ______________________________________________________________________

   F9F-6      646        Initial production Cougar.
   F9F-6P      60        Unarmed photo-reconnaissance F9F-6.
   F9F-7      168        Allison engine, most kitted to F9F-8 spec.
   F9F-8      601        F9F-6 with modified wing.
   F9F-8B       -     ?  F9F-8 with tactical nuclear strike capability.
   F9F-8P     110        Reconnaissance F9F-8 variant.
   F9F-8T     399        Tandem two-seat trainer variant of F9F-8.
   ______________________________________________________________________

            1,984        TOTAL COUGARS
   ______________________________________________________________________

   TOTAL    3,312
   ______________________________________________________________________

* Sources include:

This document owes much to an online document on the Panther / Cougar by aviation enthusiast Joe Baugher.

Grumman F9F-8 Cougar

* Revision history:

   v1.0.0 / 01 oct 07 
   v1.0.1 / 01 sep 09 / Minor corrections.
   v1.0.2 / 01 aug 11 / Review & polish.
   v1.0.3 / 01 jul 13 / Review & polish.
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