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Grumman XF9F-2 Panther The Grumman F9F Panther was the first jet-powered aircraft to be built by Grumman, a long-time manufacturer of carrier-based fighter aircraft for the US Navy. The Panther bore the brunt of carrier-based jet fighter operations in the Korean War, and had the distinction of downing the first MiG-15 to be destroyed by a US Navy plane. However, it was to be in the ground attack role that the Panther was to gain its primary claim to fame. As compared to some of its competitors, the Grumman Aircraft Corporation of Bethpage, Long Island was rather late in getting into the design of jet combat aircraft. However, between July of 1943 and November of 1944, Grumman undertook some preliminary work on several different jet-powered designs, some of them powered by a mixture of jet and piston engines. The first of these was the G-57, which was to have been powered by an R-2800 piston engine plus a small turbojet. Next was the G-61, which was a development of the F6F Hellcat with a turbojet engine in the tail. However, both of these projects had to be shelved in favor of higher-priority work on the G-58 (XF8F-1 Bearcat), a conventional piston-engined fighter. Later, Grumman began work on projects G-63 and G-71, which were both small single-jet designs. This was soon followed by the G-68, which was a single seat fighter to be powered by a TG-100 turboprop. However, none of these wartime projects attracted very much enthusiasm, and all of them were abandoned almost as soon as they were begun. Serious Grumman work on jet-powered fighter aircraft did not really get underway until after the war was over. The G-75 was a postwar project begun by Grumman in September of 1945 in response to a Navy Request For Proposals for a two-seat radar-equipped jet-powered carrier-based night fighter. The G-75 was to be capable of flying at speeds of 500 mph and at altitudes of 40,000 feet and was supposed to be able to detect the presence of enemy aircraft at ranges as great as 125 miles. The G-75 looked very much like a jet-powered F7F Tigercat, and was to be powered by four 3000 lb.s.t. Westinghouse 24C-4B turbojets mounted two each side-by-side in midwing-mounted nacelles. A radome was to be mounted in the nose, and the armament was to have been four 20-mm cannon. Competing proposals from Curtiss, Douglas, and Fleetwings were also submitted to the Navy in response to the RFP. On April 3, 1946, the Navy deemed the Douglas proposal as being the best of the lot, and ordered three prototypes under the designation XF3D-1. However, on April 11, a Navy contract was issued for the construction of two G-75 prototypes under the designation XF9F-1 as a backup just in case the Douglas design did not live up to expectations. The XF9F-1 was appreciably larger and heavier than the XF3D-1. In the summer of 1946, further design studies indicated that the Grumman design was considerably less promising than the Douglas design, and the Navy considered cancelling the XF9F-1 contract altogether. ,p. This would ordinarily have been the end of the line, but Grumman had fortuitously been working on another totally-unrelated project under the company designation of G-79 that had been initiated only a month before the two XF9F-1 night fighter prototypes had been ordered. As originally conceived, the G-79 was a much smaller single-seat fighter powered either by a single centrifugal-flow turbojet fed by wing root intakes and exhausting underneath the rear fuselage, by two wing-mounted Westinghouse J34 axial-flow turbojets, or by two Rolls-Royce Derwent centrifugal-flow turbojets mounted in the wing roots. Alternatively, during the early summer of 1946, Grumman proposed the use of a single 5000 lb.s.t. Rolls-Royce Nene centrifugal-flow turbojet which would be built under license in the USA as the J42. In case the J42 ran into unexpected difficulties, the 4600 lb.s.t. Allison J33 was considered as a possible alternative, since it was about the same size as the Nene but was somewhat less powerful. Enough interest was generated in this list of projects that the Navy was persuaded to amend the XF9F-1 contract rather than cancel it outright. On October 9, 1946, the XF9F-1 contract was amended to provide for the construction of three single-seat prototypes (BuNos 122475/122477), a static test airframe, plus design data for a swept-wing version. By November, the Navy had narrowed its choice of powerplant options and specified that two of the G-79 prototypes should be completed as XF9F-2 powered by Rolls Royce Nene turbojets and that the third should be powered by an Allison J33 turbojet and be designated XF9F-3. The Rolls-Royce Nene jet engine, was to be built under license in the USA by the Taylor Turbine Corporation as the J42-TT-2. Just in case the adaptation of the Nene to production in the USA turned out to be more difficult than expected, Grumman developed a parallel version of the Panther to be powered by the Allison J33 turbojet. The J33 engine was somewhat less powerful than the J42, but it was considered to be a safer risk. The J33-powered version was to be designated F9F-3 and was to be manufactured in parallel with the J42-powered F9F-2. Since the the J42 was not going to be ready in time to be installed in the XF9F-2, Taylor Turbine Corporation supplied six imported Rolls-Royce Nene turbojets to Grumman. By the time that the mockup was ready for inspection in January and February of 1947, the G-79 design had been further revised. The cockpit had been moved further aft, the exhaust had been extended further to the rear, and the tail surfaces had been redesigned. The first XF9F-2 prototype (BuNo 122475) began engine ground running tests in October of 1947. The maiden flight took place from Bethpage on November 21, 1947, test pilot Corwin H. "Corky" Meyer being at the controls. The landing took place at Idlewild Airport (now the John F. Kennedy International Airport), since the runway at Bethpage was thought to be too short to risk a first landing of a jet-powered aircraft. The second XF9F-2 prototype (BuNo 122477) flew five days later. Neither XF9F-2 prototype was fitted with armament nor was it fitted with an ejector seat. The wings folded upward hydraulically. A single tailhook retracted into the rear fuselage underneath the jet exhaust. Internal fuel capacity was 597 US gallons. During company
and Navy trials, the two XF9F-2 prototypes were found to snake
markedly at all speeds and were longitudinally unstable at all
speeds. The snaking problem was addressed by increasing the area
of the fin and rudder, and the longitudinal instability problem
was attacked by adding baffles to the fuel tanks. One of the prototypes
shed its tail section during an arrested landing at Patuxent River,
Maryland, which required some strengthening of the rear fuselage.
Since the Navy was fearful that the Taylor Turbine Corporation might not be able to deliver sufficient numbers of engines in a timely fashion, the Navy encouraged Taylor to negotiate an agreement whereby the Nene manufacturing license would be transferred to a more-established engine manufacturing company. This was done as requested, and the Nene license was purchased from Taylor by Pratt & Whitney. Grumman F9F-5 Panther The F9F-5 was numerically the most important of the Panther variants. It had the longer fuselage and revised tail surfaces of the F9F-4, but was powered by the Pratt & Whitney J48 turbojet, a license-built version of the Rolls-Royce Tay. The XF9F-5 prototype was the 100th production airframe (F9F-2 BuNo 123085), modified and re-engined. It flew for the first time on December 21, 1949. It actually preceded the XF9F-4 into the air by almost half a year. 616 F9F-5s were delivered to the Navy and Marine Corps between November 1950 and January 1953. They were all powered by the Pratt & Whitney J48-P-6 or P-6A, rated at 7000 lb.s.t. wet. The F9F-5 had four external store pylons underneath each wing, with the three outboard pylons being stressed to carry bombs of up to 500 pounds in weight. Maximum external load was 3465 pounds. During the
course of production, an anti-stall fence was added just outboard
of the wing roots to control the airflow and reduce landing speed.
Many of the F9F-4s were retrofitted with J48 engines and thus
became indistinguishable from F9F-5s. In November 1951, the F9F-5 replaced the F9F-2s of the Blue Angels flight demonstration team. This team began to convert to the swept-wing F9F-6 Cougar in 1953, but it turned out that these Cougars were urgently needed by the fleet and the team had to be hastily re-equipped with overhauled F9F-5s. The F9F-5s served with the Blue Angels until 1954, when they were finally replaced by F9F-8 Cougars. The first F9F-5s entered combat in Korea in October of 1952, serving aboard the USS Oriskany (CVA-34) with the reserve squadrons VF-781 and VF-783. They were also flown by VF-51, VF-52, VF-53, VF-111, VF-153, and VF-154 during the latter stages of the Korean War. They provided the backbone of the Navy's carrier-based jet-powered ground attack capability during the last year of the Korean War. One of the more significant experiments carried out by the F9F-5 was the performance of early midair refuelling tests. F9F-5 BuNo 125240 was fitted in 1952 with a refuelling probe in the nose for trials with a North American XAJ-1 attack plane modified as a tanker. These tests were so successful that the Navy eventually decided in September of 1955 to require that all of its jet-powered fighters and attack aircraft would henceforth be equipped for midair refuelling. As the Panther began to be replaced in active service by more advanced types, surviving F9F-5s were modified as F9F-5K remotely-controlled drones or as F9F-5KD drone directors. In the F9F-5KD, the nose guns were removed and were replaced by radio control equipment. In 1962, the Defense Department introduced the new Tri-Service designation scheme under which the separate USAF/Navy designations were replaced by a new unified designation system. This required that all existing Navy aircraft be redesignated. By this time, the only Panthers remaining in Navy service were the F9F-5KD drone directors, which were redesignated DF-9E. The last DF-9Es were struck off charge in the mid-1960s. Serials
of Grumman F9F-5 Panther: Specification of the Grumman F9F-5 Panther: Engine: One Pratt & Whitney J48-P-4/P-6A turbojet rated at 6250 lb.s.t. Performance: Maximum speed 604 mph at sea level, 579 mph at 5000 feet, 543 mph at 35,00 feet. Cruising speed 481 mph. Stalling speed 132 mph . Initial climb rate 5090 feet per minute. Service ceiling 42,800 feet. Range 1300 miles. Dimensions: wingspan 38 feet 0 inches, length 38 feet 10 1/2 inches, height 12 feet 4 inches, wing area 250 square feet. Weights: 10,147 pounds empty, 17,766 pounds gross, 18,721 pounds maximum takeoff. Internal fuel capacity 1003 US gallons. Armament: Four 20-mm cannon in the nose. Eight underwing hardpoints which could accommodate a total underwing load of up to 3465 pounds of bombs and rockets. Sources: 1. United
States Navy Aircraft Since 1911, Gordon Swanborough and Peter
M. Bowers, Naval Institute Press, 1990. Panther in Service with US Navy and US Marine Corps The F9F-2 and -3 initial production versions of the Panther were declared service-ready in the spring of 1949. However, because of initially-slow deliveries of the Pratt & Whitney J42, the Allison J33-powered F9F-3 was actually the first to enter service. F9F-3s were first delivered to VF-51 at NAS San Diego on May 8, 1949. The F9F-2s first went to the Blue Angels flight demonstration team based at NAS Pensacola on August 20, 1949, and a few days later F9F-2s went to VMF-115 at MCAS Cherry Point in North Carolina. The first Navy squadron to get the F9F-2 was VF-11 at NAS San Diego, which first received the machines in the early autumn of 1949. When war came to Korea on June 25, 1950, VF-51 and VF-52 loaded their F9F-2 Panthers aboard the USS Valley Forge (CV-45) and put to sea. Panthers from VF-51 were first in action on July 3, 1950, providing escort for a strike against an airfield at Pyongyang. Ens E. W. Brown and Lt(jg) L. H. Plog shared credit for downing a Yak-9, scoring the first kill credited to a Navy jet fighter. In November of 1950, the swept-wing MiG-15 began to appear over northern Korea. Although powered by derivatives of the same Rolls-Royce Nene as was the F9F-2, the MiG-15 had a much better performance because of its swept wings and lighter weight. Nevertheless, the Panther was able to defeat the MiGs in the few air-to-air encounters that did take place. The first MiG-kill by a F9F Panther was by Cdr W. T. Amen of VF-111 on November 9, 1950. Four more MiG-15s were downed by Panthers before the Korean War ended, with no Panthers being lost in air-to-air combat. The first Marine Corps Panthers appeared in combat in Korea in December of 1950. These were F9F-2Bs serving with VMF-311, helping to support the withdrawal of troops from the Chosin Reservoir. Most Panthers serving in Korea flew air-to-ground close-support missions, air-to-air action being quite rare. The first Navy F9F-2Bs appeared in combat on April 2, 1951, when VF-191 flew an attack on railway bridges near Songjin. The more capable F9F-5 first appeared in Korea in October of 1952, flown initially by VF-781 and VF-783 operating off the USS Oriskany (CVA-34). F9F-5s also served with VF-51, VF-52, VF-53, VF-111, VF-153, and VF-154. The Marine
Corps flew F9F-2Bs, F9F-4s and F9F-5s in Korea, exclusively in
the ground support role. Active and reserve Marine Corps squadrons
that flew the Panther included VMF-115, VMF-122, VMF-211, VMF-213,
VMF-214, VMF-223, VMF-224, VMF-232, VMF-234, VMF-235, VMF-311,
VMF-312, VMF-314, VMF-324, VMF-334, and VMF-451, plus the training
squadrons VMFT-10 and VMFT-20. Throughout the early 1950s, Panthers served extensively with active and reserve units of both the Atlantic and Pacific Fleets. They provided the mainstay of the Navy's jet-powered carrier-based air-to-ground capability. The Panthers were phased out of active service with the Navy in 1956, but they remained with training units until 1958. The last Marine Panther units were the two reserve squadrons VMF-213 and VMF-234, which were based at Minneapolis. These Panthers were retired in 1958. Many of the surplus Panthers were used as drones or as drone directors under the designation F9F-5K or F9F-5KD. In 1962, the Defense Department eliminated separate designations for Navy aircraft, and ordered that all Navy planes be redesignated under the new Tri-Service unified designation scheme. The Panther/Cougar was assigned the designation F-9 under the new system. By this time, the only Panthers left in service were the F9F-5KD drone directors. These were redesignated DF-9E. The last of these DF-9Es was stuck off charge in the mid-1960s. Sources: 1. United
States Navy Aircraft Since 1911, Gordon Swanborough and Peter
M. Bowers, Naval Institute Press, 1990. Grumman F9F-5P Panther The F9F-5P was a specially built unarmed photographic reconnaissance version of the F9F-5. Unlike the F9F-2Ps, which were modified from existing F9F-2 airframes, the F9F-5Ps were built from scratch as unarmed photo-reconnaissance aircraft. 36 were built. The modified nose had the armament replaced by a housing for vertical and oblique cameras. The overall length was 40 feet as compared to 38 feet 10 1/2 inches for the standard F9F-5. The F9F-5P was deployed with a detachment of VC-61 aboard the USS Princeton during late 1952, supplanting the earlier F9F-2P. F9F-5P BuNo 126275 is on display at the USN Pensacola Air Museum. Grumman
F9F-5P Panther serials: Grumman
F9F-4 Panther The 99th and 101st production airframes (F9F-2s BuNos 123084 and 123086) were modified as the XF9F-4 prototype and the static test airframe. 123084 flew for the first time on July 5, 1950, powered by a 6250 lb.s.t. Allison J33-A-16 turbojet. The F9F-4 was equipped with four external store pylons underneath each wing. The three outboard pylons were stressed to carry bombs of up to 500 pounds in weight, bringing maximum external load to 3465 pounds. The J33-A-16 turbojet proved to be unreliable in service, and many F9F-4s were delivered to the Navy as J48-powered F9F-5s, and most of the others were re-engined with J48-P-6As once they entered service. They thus became indistinguishable from F9F-5s. In early 1954, F9F-4 BuNo 125081 was modified as a test bed for a high-lift boundary layer control system. Serials
of F9F-4 Panther: Grumman
F9F-3 Panther 54 J33-powered F9F-3s were delivered to the Navy by Grumman between August 1948 and November 1949. They came off the production line in parallel with the J-42-powered F9F-2. Because of initially slow deliveries of J42 engines for the F9F-2, the F9F-3 was actually the first Panther version to enter service with the Navy, when F9F-3s replaced the FJ-1 Furies of VF-51 in May of 1949. However, the J33 turned out in service to perform less well than the J42. In October 1949 virtually all F9F-3s were re-engined with 5750 lb.s.t. Pratt & Whitney J42 turbojets, and thereby became indistinguishable from the F9F-2. No further F9F-3s would be built, and further Navy contracts would be for the F9F-2 version. In the summer of 1950, a re-engined F9F-3 (BuNo 122562) was fitted with an experimental electro-hydraulically driven Emerson Aero X17A roll-traverse turret housing four 0.50-inch machine guns. The guns could be directed at any angle from directly forward to 20 degrees aft, and the gun mount could be rolled the full 360 degrees in either direction. The turret could roll at a rate of 100 degrees per second, and the guns could be traversed at up to 200 degrees per second. Although the tests with the turret went fairly well, delays in the development of the associated radar and fire control system led to the project being cancelled in early 1954. Serials
of F9F-3: Grumman
F9F-2 Panther The first F9F-2s began their trials powered by J42-P-4 turbojets, but initial production F9F-2s were powered by J42-P-6s. Most F9F-2s were powered by J42-P-8s with a modified ignition system. All of these engines offered a maximum wet takeoff-thrust of 5750 pounds and a dry take-off thrust of 5000 pounds. The production by Pratt & Whitney of the J42 adaptation of the Rolls-Royce Nene proceeded on schedule and with relatively few snags. The J42 engine was, in fact, so successful in service that the F9F-3 alternative J33-powered version was deemed not to be necessary and the few F9F-3s that were built were retrofitted with J42 engines and thus became indistinguishable from F9F-2s. A total of 564 Panthers were delivered as F9F-2. A substantial number of early production F9F-2s were modified as F9F-2B fighter bombers by the addition of four bomb racks underneath each wing. The inboard rack could carry either a 150-gallon drop tank or a 1000-pound bomb, whereas the three outboard racks could carry 250-pound bombs or 5-inch HVAR rockets. Maximum load was 2000 pounds. Beginning with the 365th F9F-2 (BuNo 125083), these racks were installed at the factory. After most F9F-2s had been brought up to F9F-2B standards, the B suffix was usually dropped. When the Korean War began in June 1950, the Navy had no jet-powered reconnaissance aircraft, since the McDonnell F2H-2P Banshee still had not undergone its first flight trials. As a stopgap measure, a small number of F9F-2s were modified as unarmed photographic reconnaissance aircraft under the designation F9F-2P. The four 20-mm cannon were removed and replaced by oblique and vertical cameras. Following the withdrawal of the F9F-2 from service, a few F9F-2s were modified as unarmed radio-controlled drones under the designation F9F-2D. A few F9F-2s were modified as drone controllers under the designation F9F-2KD. F9F-2 BuNo 123050 is on display at the USN Pensacola Air Museum. Serials
of Grumman F9F-2 Panther: F-9 / F9F-2 Panther The McDonnell Company of St. Louis built the Navy’s first all jet aircraft and demonstrated that the jet engine was adaptable to naval aviation, but it was Grumman’s F9F Panther that became the first Navy jet fighter to shoot down another jet fighter. Grumman’s departure from propeller driven fighters was accompanied by abandoning the tradition of naming the Company’s fighters "Cats." However, the feline connection lived on with Panther and Cougar and eventually returned to original policy with the F-14 Tomcat. Grumman received a Navy contract on 16 December 1946 to produce a jet powered, straight wing, carried based fighter. The aircraft Grumman proposed first flew on 21 November 1947 and was eventually designated and named the F9F-2 Panther. It was first delivered to Navy squadron in May 1949 and remained in service until October 1958. The Navy accepted a total of 1,388 Panthers with designations of F9F-2, F9F-3, F9F-4 and F9F-5. With the Panther, Grumman maintained its position into the jet age as a major supplier of Navy carrier fighter aircraft. The Panther never enjoyed the recognition of Grumman's last piston engine fighter, the F8F Bearcat, as a spectacular performer. However, it did extend Grumman's reputation for building rugged, effective fighter aircraft. The F9F series began when development was initiated on the large two-place four-jet XF9F-1 night fighter. Before design work was completed, the XF9F-1 was dropped and the project shifted to the single-place, single-jet XF9F-2 day fighter. The imported Rolls-Royce Nene jet engines of the two XF9F-2 prototypes were replaced in production F9F-2s by Pratt & Whitney-built J42 Nenes. In the XF9F-3 and production F9F-3s, an Allison J33 replaced the Nene. Only engine installation details differed between the -2 and -3 Panthers. Permanently attached tip-mounted external fuel tanks were the most obvious change added to all Panthers early in the program. While the first aircraft to see squadron service were the -3s, which VF-51 received in May 1949, the Nene-powered -2 became the sole production version following early deliveries. An increased thrust version of the Allison J33 led to the -4 with a longer fuselage and increased area vertical tail. The same airframe with the P&W-produced J48 version of the Rolls-Royce Tay engine became the F9F-5. The -5s joined the -2s as the major production versions. Photo versions, the Navy-modified -2P and Grumman-built -5P, also served in carrier air groups of the early Fifties. A total of 1,385 Panthers were delivered to the Navy. The Panthers became a mainstay of Navy and Marine forces in Korea. They were the first carrier jets to fly in combat, shooting down two YAK-9s on their first mission in July 1950. Later, in November, LCdr. W. T. Amen, C.O. of VF-111, was the first carrier jet pilot to shoot down a MiG-15. In 1954, flight tests of the first fly-by-wire aircraft, a modified F9F Panther jet, were initiated at Langley. The primary objective of the tests was to evaluate various automatic control systems, including those based on rate- and normal-acceleration feedback. However (as is the case in many research investigations), the most valuable result of the flight test was related to secondary objectives—in this case the introduction and evaluation of fly by wire and a sidestick controller for pilot inputs. In a serendipitous approach, Langley researchers decided to avoid the relatively large expense and time required to modify the existing hydraulic flight control system for the F9F. Instead they chose to implement an auxiliary system based on a fly-by-wire analog concept and a small (4 in.) sidestick controller mounted at the end of the armrest at the side of the pilot. The sidestick controller was used as the maneuvering flight controller throughout the investigation. Rapid and precision maneuvers such as air-to-air tracking, ground strafing runs, and precision landings were evaluated. The objectives of the flight program were completed with great success, and the information on various types of automatic control feedback was used for numerous aircraft development programs. However, the very successful use of the rudimentary fly-by-wire and sidestick controller concepts generated considerable excitement within the research community, especially those visionaries that anticipated the weight saving advantages for future aircraft. Additional research was conducted at Langley on these systems, including the use of a sidestick controller for the Apollo mission. As the -4 and -5 Panthers replaced the -2s in
carrier squadrons, the -2s took over advanced training, drone/drone
control, reserve squadron and other duties, followed in turn by
the -4s and -5s as they were replaced by their swept-wing F9F-6
successors. The last Marine combat squadrons to use Panthers kept
their -5s until late 1957, and a few drone F9F- 5KDs remained
to be redesignated DF-9Fs under the 1962 DOD redesignations. |
