1999, p. 5. equipped with a Doppler unit to allow some basic look-down capabilities. The bombing system was the anglicized version of the Lear/Siegler AN/ABJ-7. Fleet Air Arm Phantoms were fitted with a double-telescoping front landing gear strut that could extend , the increased angle of attack being necessary for catapult launches from the smaller British carriers. Other British contractors, including Short Brothers and British Aircraft Corporation, built sub-assemblies and supplied parts to the United States where the aircraft were assembled by McDonnell Douglas at Saint Louis. A Spey-powered Phantom was not a new concept: McDonnell Douglas had considered the idea to meet the USAF TFX requirement, later satisfied by the General Dynamics F-111. The Spey gave an increase of 10% in operational range, 15% increase in ferry range and better low-level acceleration, however the increased drag of the engine installation resulted in poorer performance at high altitude. Although some of the design changes were unique to the British aircraft – folding radar radome, Spey engine, nose-wheel extension and strengthened arrester hook – the other structural changes and improvements were used in the design of the F-4J. After modifications in the 1970s, the tail had a new RWR system; a British-made Marconi ARI.18228 fitted in a rectangular antenna box on the fin tip. Initially, a total of 140 FG.1s were to be ordered for the Fleet Air Arm; the intention was to operate the Phantom from both of the Royal Navy's remaining large fleet carriers, Eagle and Ark Royal, and the brand new CVA-01 carriers. However, the 1966 Defence White Paper saw the cancellation of the CVA-01 project, with the Royal Navy's Phantom order cut to 48. This was intended to provide for two squadrons each of 12 aircraft to be operated from Eagle and Ark Royal, both of which were to be heavily modified. While Ark Royal was undergoing conversion, the FG.1 underwent successful deck trials aboard Eagle. In 1969, however, the decision was taken that Eagle would not undergo conversion, leaving Ark Royal as the only Royal Navy carrier capable of operating the Phantom. As a consequence, 20 of the Fleet Air Arm's FG.1s were diverted to the Royal Air Force to equip No. 43 Squadron at RAF Leuchars in the air-defence role. These aircraft were modified to enable them to carry the SUU-23/A gun pods. The units equipped were 700P Naval Air Squadron trials unit, 767 Naval