For a time in military aviation history, the rocket-powered fighter / interceptor stood as the potential future of aerial combat. This approach was laid down in the World War 2 period (1939-1945) when German engineers realized the Messerschmitt Me 163 "Komet", a single-seat, single-engine rocket-powered fighter / interceptor (detailed elsewhere on this site). The design was not without its issues for its fuel was highly volatile - making it as much a danger to its pilot as to any Allied bomber - and the stores burned rather quickly - giving the little warplane very limited endurance when intercepting bomber formations; perhaps enough burn to complete two strafing passes into the group. To this was added the lack of an onboard undercarriage requiring the pilot to land his aircraft in a relatively smooth open field on a simplistic belly-mounted skid.
From this approach came the vision that the future of aerial warfare would be dominated by fast and nimble rocket-powered warplanes, capable of exceptional inherent speeds and sporting an outstanding rate-of-climb. In Britain, there were many projects drawn up for this very purpose though few were eventually realized due to the post-war draw-down - and the turbojet ultimately became the fixture of warplanes for the foreseeable future which left rocket-centric vehicles to power the various space programs that unfolded in the Cold War period (1947-1991).
The need for rocket-powered interceptors was driven home with the fear of ever-increasing capabilities of Soviet bombers and reconnaissance planes as these high-flying terrors might push the limits of ground-based air defense systems and those manned interceptors relying on air-breathing turbojet engines. A rocket-powered interceptor, therefore, could provide the answer, giving a reach upwards of 60,000 feet and beyond, providing a direct counter to marauding enemy warplanes.
Against this backdrop, the British concern of Saunders-Roe penciled out what it believed to be a sound rocket-powered interceptor contender in the "P.154". The company is long-remembered as a flying boat builder and its designs were used throughout the fighting of World War 2 in various capacities. However, it also knew how to push the boundaries of aeronautics design for its part in aviation history with many forward-thinking and unique proposals offered during the post-World War 2 period.
The design of the aircraft was certainly modern by 1950s standards, incorporating a short nosecone assembly ahead of the single-seat, pressurized cockpit. The pilot would sit under a two-piece canopy that offered generally unobstructed views (though the rear was partially obscured by the raised dorsal fuselage spine). The wing mainplanes were situated at midships (and were mid-mounted along the fuselage sides) while given a large-area surface. The leading edges were supplied good sweepback for the high-speed flight envelope while the trailing edges countered with straight lines, these also containing the needed control surfaces. The tail unit had just one vertical fin and mounted its elevators low (yet above the mainplane's wash). Internally, there would be a twin-chambered rocket motor outputting a combined 8,000lb of thrust (one or both of these chambers could be selected by the pilot based on flight phase: covering general cruising or high-speed interception actions as needed). Since the rocket engine did not require air-breathing (as a turbojet would), no intakes were present. The unit exhaust by way of a conventional ring positioned at the extreme rear of the design and under the tail fin in the usual way.
As with the wartime Me 163 rocket fighter, the P.154 was to have relied on a jettisonable, three-wheeled "dolly" for its ground-running /take-off action and have to land on a skid-equipped belly for the return trip.
Beyond the proposed internal rocket engine, which would have been an in-house Saunders-Roe-developed rocket motor, the design was also proposed with additional take-off thrust by way of rocket boosters and another idea involved the installation of a compact turbojet for propulsion power for the return trip home.
In terms of armament, the P.154 was envisioned as having two retractable housings at the rear section of the fuselage to contain 25 x RP aerial rockets each. Only later was thought being given to supporting 2 x "Blue Jay" air-to-air missiles. In either case, both weapon arrangements were strictly intended for the interception role and mainly for large enemy warplanes such as bombers (whose airframes often went on to double as reconnaissance platforms due to their inherently good range).
While never built, SARO engineers provided some estimates for their proposed creation: it would have a maximum speed reaching nearly Mach 2.5 at altitudes of 60,000 feet and climb-rate would be in excess of 13,500 feet-per-minute - qualities brought about by the focus on rocket propulsion (though at the expense of limited range due to excessive fuel burn). The aircraft was to have reached 60,000 feet in a little over two minutes and, beyond this, the structure would see a running length of 37 feet with a wingspan of 26 feet. Gross weight was to reach nearly 13,300lb.
At any rate, the P.154 was not furthered beyond its paper stage though Saunders-Roe's own "SR.53" development, detailed elsewhere on this site, at least went on to make it to the prototype stage before being terminated.