McDonnell Douglas F-4 Phantom II RF-4C

McDonnell had been thinking about a reconnaissance Phantom from the very beginning of the Model 98 project in the early 1950s: as early as 25 August 1953 it offered the US Navy an unarmed photographic version, the 98F. Nothing came of it at the time, but the later Model 98AX (September 1958) and Model 98DF (January 1961) proposals eventually led to Specific Operational Requirement 196, approved by the Air Force on 31 December 1962. The programme ran in parallel with that of the Model 98DH, the Marine Corps' RF-4B, from which the Air Force aircraft differed only in the same respects that separated the naval F4H-1 from the F-110A.

Even before SOR-196 was issued, in May 1962 the Navy had instructed McDonnell to convert six F-4Bs into two YRF-110A prototypes (62-12200 and 62-12201) and four RF-110A development aircraft. The mock-up was reviewed in October 1962, by which time the designation had already become RF-4C under the new unified system. Optical and electronic reconnaissance systems were tested during 1963 at Holloman aboard a bailed F-4B, and the first YRF-4C (62-12200) made its maiden flight on 9 August 1963 with William S. "Bill" Ross at the controls. It already had the extended nose but carried no cameras; the second prototype, which flew on 30 September 1963, was fitted with panoramic and frame cameras but still lacked most of the other systems planned for production aircraft.

The most obvious difference was the new, longer and more pointed nose, where the fighter's AN/APQ-72 fire-control radar gave way to a suite of specialised sensors. Inside were three camera stations: the forward station, just behind the radar, took a single forward-oblique or vertical KS-87; the second, "low-altitude" station normally carried a KA-56 low-altitude panoramic camera, replaceable by a trio of KS-87s (vertical, left and right oblique) or a vertical KA-1; and the third, "high-altitude" station, just ahead of the cockpit, usually held a KA-55A or KA-91 high-altitude panoramic camera in a stabilised mount, with KC-1 or T-11 mapping cameras as alternatives. For night photography a photoflash cartridge ejection system was installed on the upper rear fuselage behind hydraulically actuated doors.

The radar became the much smaller Texas Instruments AN/APQ-99, a two-lobe monopulse J-band set with terrain-avoidance and terrain-following modes and a ground-mapping capability, later replaced by the AN/APQ-172 in all surviving RF-4Cs. Just aft of the nosewheel bay sat an AN/AAD-5 or AN/AAS-18 infrared linescan set, and on either side of the lower nose were the antennas of the Goodyear AN/APQ-102 side-looking mapping radar, replaced on some aircraft by the AN/APD-10 with an extended-range antenna podded in a modified external tank and a UPD-8 datalink that could send radar imagery to ground stations in real time. The ARC-105 high-frequency radio needed a large shunt antenna recessed into the fin, which meant deleting the upper pitot head. Many RF-4Cs were later given an aerodynamically refined nose with a bulge over the camera housing that allowed larger cameras to be fitted.

The rear cockpit, occupied by the reconnaissance systems operator, had a stick and rudder pedals, and on many occasions, especially on long overwater legs, the back-seater did fly the aircraft. But the view from the rear was very poor, the landing gear could only be lowered from there by pulling the emergency handle, which depleted the hydraulics and left the aircraft without wheel brakes, and neither the arrester hook nor the drag chute could be deployed, so landing from the back seat was difficult if not downright dangerous.

Initially the RF-4C carried no weapons and the F-4C's underfuselage Sparrow slots were omitted. In an emergency it could carry a nuclear weapon on the centreline, something rarely practised, although the aircraft of the 10th Tactical Reconnaissance Wing in Europe were fitted with the AJB-7 low-altitude bombing system just in case. In later years they gained AIM-9 Sidewinder missiles for self-defence on the inner wing pylon and an AN/ALQ-115 or AN/ALQ-184 electronic countermeasures pod under the starboard wing.

The electronic warfare fit was upgraded continuously over a very long service life: radar homing and warning receivers ALR-17, -31, -46, -50 and -126, until the USAF standardised on the AN/ALR-46A. Later additions included Litton's AN/ALQ-125 TEREC tactical electronic reconnaissance sensor (originally known as Pave Onyx) with a datalink for near-real-time transmission, the Lear Siegler AN/ARN-101 digital navigation unit, the EWACS electronic wide-angle camera system and, on 39 specially wired aircraft, the AN/AVQ-26 Pave Tack infrared pod, a few of them with the AN/AVQ-9 laser designator slaved to the sensor. In 1970, twenty RF-4Cs, all eighteen Block 40 aircraft and two from Block 41, received the ARN-92 LORAN-D navigation system with its distinctive "towel rail" antenna on the upper rear fuselage, giving all-weather blind navigation.

For long-range oblique photography the RF-4C could carry the gigantic General Dynamics HIAC-1 camera inside a large G-139 centreline pod, a system originally developed for the RB-57F and capable of showing astonishing detail at stand-off distances of up to 100 miles; several so-equipped aircraft flew along the North Korean and Eastern European borders, although the huge pod severely compromised performance. Later, 24 aircraft were adapted for the CAI KS-127A or KS-127F LOROP camera with a 66-inch focal length in stations 2 and 3. From aircraft 69-0375 onward the low-altitude panoramic camera could be used with an ejectable film cassette that descended by parachute with a locator beacon; the system proved impractical in the field and was replaced in South-East Asia by rapidly deployed film-processing vans.

The first production RF-4Cs went in September 1964 to the 33rd Tactical Reconnaissance Training Squadron at Shaw AFB, South Carolina, and the first operational unit, the 16th Tactical Reconnaissance Squadron of the 363rd Wing, reached combat readiness in August 1965, even though many aircraft still flew without their full equipment and with unqualified components. The last of 503 production RF-4Cs was delivered in December 1973: more than ten years in production, a run exceeded only by the F-4E among all Phantom versions.

The 16th TRS deployed to Tan Son Nhut in South Vietnam in October 1965, and the 15th TRS entered combat in February 1967. Early missions revealed a long list of problems: the AN/APQ-102A side-looking radar was highly unreliable and took years to fix, the AN/AAS-18 infrared sensor was defective, the aircraft shared the F-4C's faulty relay potting compound, and airframe vibration distorted the camera imagery. Even so, over the following eight years the RF-4Cs of the 11th, 12th, 14th and 16th squadrons flew from Tan Son Nhut and Udorn in Thailand over North and South Vietnam and Laos, mostly by day, alone and unescorted. No RF-4C was lost to a MiG, but 7 were shot down by surface-to-air missiles and 65 by anti-aircraft artillery or small arms; four more were destroyed on the ground and seven were lost in accidents. Given the number of sorties flown, the loss rate was regarded as low.

The RF-4C was the first Phantom version to reach the Air National Guard: Alabama's 106th TRS received it in February 1971 in place of its RF-84Fs, and eventually nine Guard squadrons plus a training unit in Idaho were equipped. By early 1989 seven active-duty squadrons remained, at Shaw, Bergstrom, Kadena and Zweibrücken, and the end of the Cold War accelerated retirement plans until Iraq's invasion of Kuwait in August 1990 put them on hold. Alabama's 106th TRS deployed to Sheikh Isa in Bahrain on 24 August 1990 and its LOROP-equipped aircraft surveyed Iraqi forces in Kuwait and along the Saudi border, losing one aircraft in an accident on 8 October 1990. Nevada's 192nd TRS relieved it in December, followed by RF-4Cs from the USAF's 12th and 38th squadrons, many of them Vietnam veterans. From the first strikes on 17 January 1991 the RF-4Cs were in action over Kuwait and Baghdad, hunting rocket-fuel and chemical-weapons plants and command centres, and were repeatedly diverted to search for Scud launchers in western Iraq. None was lost in combat; one crashed into the Persian Gulf after the ceasefire, its crew ejecting safely.

Within a year of Desert Storm the RF-4C had all but vanished from the USAF: the 26th Wing stood down in April 1991, the 91st TRS ended active-duty service in September 1991 and the 12th TRS held on until 1994. In the Guard, several units converted to the tanker mission with KC-135s between 1992 and 1994, Idaho moved to the F-4G, and Nevada's 192nd handed in its last four aircraft on 27 September 1995, flying them to Davis-Monthan. Abroad, two aircraft were loaned to Israel in 1970-71, twelve ex-USAF machines went to South Korea in 1989, and Spain received twelve under the designation CR.12, which after successive upgrades served until 2002. The first YRF-4C, 62-12200, enjoyed a second life as a test bed: aerodynamic prototype for the F-4E in 1965, trials aircraft for the Agile Eagle leading-edge slats, a beryllium rudder, a fly-by-wire control system in 1972 and canards under the PACT programme in 1974, before being donated to the USAF Museum at Wright-Patterson in January 1979, where it remains on display.