Into the 1960s, the British Royal Air Force (RAF) found itself in need of a budget-minded Advanced Jet Trainer (AJT) with inherent light strike capabilities. This led to a series of design brochures being published by the various British aero-industry players of the day. The Folland Fo.147 became a product of this period and held roots in the classic twin-seat, single-engine Folland "Gnat" fighter-trainer of 1959 (this aircraft is detailed elsewhere on this site). The Gnat found modest value on the global stage for its time, serving in the air forces of Britain, Finland, and India.
The Fo.147 was formed from the proposed supersonic, missile-armed, twin-seat, twin-engine Gnat Mk.5 fighter-trainer model. Key to Fo.147's design was integration of a "Variable Geometry" (VG) - or "swing wing" - capability in an effort to exact every ounce of speed and performance from the compact aircraft. Folland engineers believed that a VG arrangement in the Gnat could bring about speeds in excess of Mach 2 all the while retaining the proven inherent qualities of the existing aircraft - in this way, the revision would help increase all performance aspects of the original including operational range, straight-line speed, and operating ceiling.
Within the Fo.147 application, the wing sweep mechanism would allow the mainplanes to actively sweep (as needed) from an angle of 20 degrees to as much as 70 depending on the current flight phase - allowing the modified Gnat to operate equally-effectively at both low- and high-speed flying envelopes. Power would be provided through 2 x Rolls-Royce RB.153R series afterburning turbojet engines in a side-by-side arrangement within the body of the aircraft - these aspirated by side-fuselage intakes.
Another unique quality of the Fo.147 proposal, beyond its intended swing-wing capability, was the use of a rotating/retracting canard foreplane unit ahead of the cockpit section. This would take the place of any horizontal tailplanes in the design, leaving just the single vertical fin mounted aft of, and above, the engine installations.
A tandem, two-seat cockpit would feature pressurized workspaces for the crewmen and ejection seats were a must for enhanced survivability. Like the proposed Gnat Mk.5, the Fo.147 could be equipped with an Airborne Interception (AI) radar in the nose, most likely the Ferranti AI.23 series unit. Ground-running would be made possible by a retractable tricycle arrangement.
Dimensions included an overall length of 51 feet with a wingspan measuring 36.5 feet. Gross weight reached 18,500lb. With its engine pairing and unique wing arrangements, Folland engineers estimated their unique aircraft to have a maximum speed of Mach 2.2 with near-Mach 3 speeds deemed possible at some point.
While the Fo.147 and its related aircraft, the proposed Fo.148 featuring a more conventional tail unit, were ultimately abandoned, the requirement was eventually filled by the SEPECAT "Jaguar" (detailed elsewhere on this site). Beyond a single prototype, thirty-eight "Jaguar B" / Jaguar T.2 AJTs, offering an inherent secondary attack functionality, were taken into service.