The F-4K was the export model of the Phantom designed for the Royal Navy.
The Royal Navy had originally planned to purchase the Hawker Siddeley P.1154 Mach 2 V/STOL fighter as its primary carrier-based fighter aircraft. However, even before the British government cancelled the P.1154 project altogether, the Royal Navy had dropped out of the project, citing its high cost and protracted development schedule. This left the Royal Navy with no replacement for its fleet of ageing DeHavilland (Hawker Siddeley) Sea Vixens. During that time period, the British government happened to be involved in discussions with McDonnell in St Louis on their proposal for a version of the Phantom suitable for British requirements. On July 1, 1964, the Royal Navy gave the official go-ahead for a version of the Phantom to fulfill its needs.
The Royal Navy Phantom was originally to have been based on the US Navy F-4B. In fact, the original designation for the Royal Navy Phantom was to have been F-4B(RN). However, a change in plans led McDonnell to use the F-4J as the basis for the new aircraft, and the designation F-4K was assigned to the project.
Shortly after the initial approval of the Phantom by the Royal Navy, an order was placed with McDonnell for two YF-4K-26 prototypes and two F-4K-27 production aircraft. Production examples were ordered later. The original Royal Navy order was for 143 Phantoms, but cuts in the carrier fleet resulted in a reduction to 137, then to 110, and finally to only 50 plus an option for seven more.
The F-4K had a number of major modifications which were needed to permit its use aboard the smaller British carriers. Another important requirement was that it was to have 40 to 45 percent of its components produced in the United Kingdom.
The most important difference between the F-4K and the F-4J was the replacement of the J79 turbojets of the F-4J with a pair of 12,250 lb.s.t. dry and 20,515 lb.s.t. with afterburning Rolls Royce RB.168-15R Spey 201 turbofans. The additional power offered by the Spey was thought to be essential in order to provide sufficient power to operate the Phantom safely from smaller British aircraft carriers. In addition, the Spey was able to provide more bleed air for the boundary layer control system, which would permit slower approach speeds. However, the increased power of these engines required that the air intake area be increased by twenty percent and that the lower portion of the aft fuselage be redesigned.
A double-extensible nose undercarriage leg was used to enable high angle of attack carrier launches to be made. The gear could be extended in length by as much as 40 inches. This arrangement was first tested on a Navy F-4B during trials aboard the USS Forrestal. In the interest of achieving slower carrier landing approach speeds, larger wing leading edge flaps were fitted and boundary layer control was applied. The amount of anhedral on the stabilator was reduced, and slats were provided on the stabilator leading edge. 16 1/2 degree drooped ailerons were fitted, which is a fancy way of saying that with gear and flaps down, the neutral position of the ailerons automatically changes to 16 1/2 degrees downward deflection.
The Ferranti AN/AWG-11 fire control system was installed in the F-4K in place of the AN/AWG-10 of the F-4J. The British-manufactured AN/AWG-11 was a license-built version of the AN/AWG-10, and differed from the American-built version mainly in having a radar dish which could be swung sideways in order to reduce the aircraft's length to 54 feet so that it could fit on the small deck lifts of British carriers.
The initial Royal Navy contract was for two prototype YF-4Ks (Royal Navy serial numbers XT595/XT596) and two pre-production F-4Ks (XT597/XT598). The two YF-4Ks were development test aircraft which were powered by Spey engines but had primarily American-built equipment. The first YF-4K (XT595) took off on its maiden flight at St Louis on June 27, 1966. It was followed by XT596 on August 1. Both machines were sent to Edwards AFB for engine trials.
The first pre-production F-4K (XT597) flew for the first time on November 1, 1966. The two pre-production machines had more British-built equipment. The British subcontractors were Short Brothers, BAC, and Rolls Royce. British-built subassemblies were shipped to St Louis for assembly by McDonnell. Unfortunately, the complex offset agreements increased the unit price of the F-4K and caused delays. In addition, Britain had to shoulder all the development costs of the Spey, which raised the price even further.
The Royal Navy ordered 48 production F-4Ks (XT857/XT876 and XV565/XV592). They were designated Phantom FG.Mk 1 in Royal Navy service. The "FG" designation meant that they fulfilled both fighter and ground-attack duties. They differed from the two YF-4Ks and the two pre-production F-4Ks in having Spey 202/203 turbofans, and were fitted with all specified British-built equipment items.
The Royal Navy F-4K could be recognized by the quadrant on the rear fuselage which allowed deck crews to check that the stabilator was set at the correct angle for a catapult launch. The F-4K had three landing approach lights mounted in a vertical strip on the nose landing gear door. In addition to the Ferranti AN/AWG-11, which was a license-built version of the AWG-10, other British-built equipment included a Plessey PTR-373 receiver and transmitter, a Dowty Electronics UHF standby receiver amplifiier, and a PTR-374 D403P UHF airborne emergency transmitter/receiver.
The first three Royal Navy Phantoms were delivered to Yeovilton on April 29, 1968. The initial trials and crew training were handled by No. 700P Squadron, after which No. 892 Squadron was formed for carrier-based operations and No. 767 Squadron was assigned the task of handling crew training.
The only Royal Navy operational unit to fly the Phantom, No. 892 Squadron, was commissioned on March 21, 1969. It became carrier qualified aboard the USS Saratoga (CVA-60) in the autumn of 1969. It embarked for the first time aboard HMS Ark Royal in June of 1970. The primary role of the Phantom FG Mk 1 was air-to-air interception, with a secondary role of ground attack.
As compared to the General Electric J79-powered Phantom, the use of the Spey produced a ten percent increase in the operational radius and a 15 percent increase in ferry range. Better take-off, initial climb, and low-level acceleration figures were obtained. However, the Spey-powered Phantom had a lower maximum speed, a lower ceiling, and a generally poorer altitude performance.
Following the introduction of the Phantom FG.Mk 1 into service, the Royal Navy suffered from an unexpectedly rapid drawdown of its carrier force. The cost of refitting HMS Eagle for Phantom operations had turned out to be prohibitively high, and HMS Victorious had to be retired early because of an onboard fire. This left only the HMS Ark Royal as a Phantom "platform". Since the Royal Navy now didn't need as many Phantoms as before, only 29 Phantom FG.Mk 1s were actually delivered to the Royal Navy. The remainder were immediately diverted to the Royal Air Force, which was already receiving its own version of the Phantom, the FGR.Mk 2. These Phantom FG.Mk 1s were turned over to No. 43 Squadron at RAF Leuchars in Scotland. This squadron had been reformed on September 1, 1969 to operate Phantom FG.Mk 1s which were surplus to Royal Navy requirements, and was given the responsibility of the air defense role. Most of the other Royal Air Force Phantom FGR. Mk 2s served in the strike/attack role.
The last Phantom FG.Mk 1 (XV592) was delivered on November 21, 1969.
In later years, the Royal Navy's Phantoms were fitted with Marconi ARI 18228 radar warning receivers mounted inside a large box-like antenna fairing sitting on top the tail fin. Also, many British Phantoms received a three-stage radar upgrade, including a Sidewinder Expanded Acquisition Mode.
The F-4K carried no internal cannon nor could it carry the SUU-23/A underfuselage cannon pod. However, F-4K aircraft transferred to the RAF were later made compatible with this gun pod.
In 1978, the British government decided that it could no longer afford to maintain carriers capable of operating conventional fixed-wing aircraft, and the HMS Ark Royal was decommissioned. The last Phantom launch from HMS Ark Royal took place on November 27, 1978. This meant the end of the line for No. 892 Squadron, and the unit was disbanded on December 15, 1978. Its Phantom FG Mk Is were transferred to the Royal Air Force by the end of 1978. After that time, the Royal Navy switched to smaller carriers carrying V/STOL Harriers.
When transferred to the RAF, ex-Royal Navy FG Mk 1 aircraft were assigned to No. 111 Squadron. No. 111 Squadron had been formed at Leuchars, Scotland in 1975 to assume air defense duties and had flown Lightning interceptors. It converted to ex-Navy Phantoms in 1978-1980. No. 111 Squadron flew its Phantoms in the air defense role, its primary responsibility being the patrolling of the Iceland-UK "gap". It relinquished its Phantoms when it converted to the Tornado F.Mk 3 in 1990.
No. 43 Squadron of the RAF flew its last Phantom mission on July 1, 1989. It converted to the Tornado F.Mk 3 shortly thereafter.
The Royal Navy lost seven Phantoms in accidents during service. A further eight of them crashed after they were transferred to the RAF. Phantom FG Mk 1s are now in storage and are no longer flying. However, it is possible that they might be sold to another user.
Royal Navy serials for Phantom FG.Mk 1:
XT595-XT596 McDonnell YF-4K-26-MC Phantom XT597-XT598 McDonnell F-4K-27-MC Phantom XT857-XT858 McDonnell F-4K-30-MC Phantom XT859-XT862 McDonnell F-4K-31-MC Phantom XT863-XT870 McDonnell F-4K-32-MC Phantom XT871-XT876 McDonnell F-4K-33-MC Phantom XV565-XV571 McDonnell F-4K-34-MC Phantom XV572-XV578 McDonnell F-4K-35-MC Phantom XV579-XV585 McDonnell F-4K-36-MC Phantom XV586-XV592 McDonnell F-4K-37-MC Phantom XV604-XV610 order not taken up