Armstrong Whitworth AW.169
High-Altitude Mach 2 Interceptor Proposal
The Armstrong Whitworth AW.169 was proposed in the 1950s as a high-speed, high-altitude interceptor to counter the Soviet threat.
Authored By: Staff Writer | Last Edited:
As tensions between the East and West rose during the Cold War period (1947-1991), and military technology advanced at a feverish pace alongside it, the primary conventional threat to Britain lay in the potent, nuclear-capable Soviet bomber force. Into the 1950s, by which point the turbojet engine was the undisputed road to future aerial victory, aircraft were ever-more capable of flying higher and faster than before - exceeding speeds beyond Mach 2. To counter the threat posed by potential marauding enemy raiders, various programs were undertaken by British aerospace firms to find a local solution in the form of a Mach 2-capable, high-altitude interceptor/day-night fighter.
From meetings and studies conducted throughout the early-to-mid-1950s, authorities drew up a "wish list" of sorts, detailing the type of interceptor that was required to stay one step ahead of the Soviets. This involved a design of very advanced form offering considerable performance with the capability to utilize an "all-in-one" weapons arrangement involving onboard systems and externally-launched Air-to-Air Missiles (AAMs). Beyond the speed requirement would be an excellent rate-of-climb to ensure the aircraft could get to altitude in short order - and then fly out to the target at supersonic speeds. It was envisioned that a crew of two would be needed to properly man the airplane and its required systems and sub-systems to their fullest and it was also intended that this aircraft would reach Initial Operating Capability (IOC) as soon as 1962 - at which point several in-service interceptor-types would already be seeing their retirement. For the Armstrong Whitworth concern, the timetable saw a first-flight tentatively scheduled for mid-1959 and Initial Operating Capability (IOC) reached by mid-1962.
Specification F.155T was eventually written up and released on January 15th, 1955 for the new interceptor while a separate specification was forged for a compatible AAM that would supply the aircraft's inherent firepower (no fixed cannon armament was to be fitted).
The Radar Fit
The radar-of-choice for the new aircraft became the AI.18 ("Airborne Interception" Mk.18) series to be fitted into a hollowed-out space in the nosecone. This X-band unit would be supplied by GEC (General Electric Company) and built upon the framework of the existing Mk.16 series that was intended for the Gloster "Javelin" all-weather fighter-interceptor (detailed elsewhere on this site). This same unit went on to provide service for the new de Havilland "Sea Vixen" fleet defense fighter (also detailed elsewhere on this site). Range of the radar reached up to 20 miles.
The AW.169 Takes Shape
Armstrong Whitworth, having built planes since before the First World War (1914-1918), provided a possible design to fulfill the rather lofty requirement - this becoming the proposed "AW.169". Its layout had origins in the earlier research-minded AW.166 which helped to evolve the initiative. The resulting design utilized a super-slim, dart-like fuselage to contain the radar fit in the nose, a twin-seat, side-by-side cockpit emplacement, avionics, and fuel stores. The cockpit split the crew members by having only the pilot under the lightly-framed canopy seated towards port side and the radar operator buried (slightly lower) within the fuselage along starboard (under a shallow blister-style covering). The ultra-thin wing mainplanes were swept back at the leading edges and straight at the trailing edges with clipped wingtips. These members were further shoulder-mounted along the fuselage sides and positioned at midships. Passing through each member at their respective midway point was a "paired" engine nacelle utilizing a single aspiration point (complete with variable-depth, high-speed shock cone) at front and split exhaust ports at rear. The nacelles extended well-ahead of the wing leading edges. The tail unit would rely on a single vertical fin supporting high-mounted, all-moving horizontal planes. For ground-running, a short-legged conventional, retractable tricycle arrangement would be featured. Construction would incorporate lightweight, though strong, alloys.
The interceptor's weapon loadout was to be 2 x Air-to-Air Missiles (AAMs), one seated at each wingtip. This would be used in conjunction with the nose-mounted radar fit and onboard crew-managed systems to create a potent ranged counter for Soviet bombers.
Engines and Structure
Power would stem from 4 x de Havilland "Gyron Junior" PS.53 turbojet afterburning (reheat) engines paired with a single Spectre rocket unit offering upwards of 15,000lb of thrust combined. The Gyron Junior, a downsized version of the de Havilland Gyron, was in-the-works in the early-to-mid-1950s and first-run in August of 1955. It entered service with such types as the eventual Blackburn "Buccaneer" naval fighter detailed elsewhere on this site. The rocket unit, buried in the underside of the fuselage, was intended for short-term concentrated bursts. This sort of augmented performance would have assisted in getting the new interceptor to the required Mach 2.0 speeds (and much faster in a dive).
Dimensionally, the aircraft was to have a running length of 84 feet with a span of 51.7 feet, making it much more long than wide. By the end of it all, the AW.169 was to gross in the vicinity of 54,000lb making it a large, powerful interceptor on paper.
The End of the Road
Despite the promise held by the AW.169 design, it never advanced beyond its paper stage, a cockpit mockup, and wind tunnel testing. There was considerable work still to be had for this advanced interceptor form so attempting to make the 1962 IOC date was a long shot at best. As such, it went on to join many other offerings of the period in going nowhere - but nevertheless showed just how forward-thinking British aerospace was in the "Age of the Turbojet".