The Saunders-Roe SR.53 mixed power-plant high performance interceptor used as main engine a Armstrong-Siddeley A.S.V.8 Viper 101 turbojet of just 1,640 lb thrust mounted high in the narrow fuselage just below the swept T tail. Just below and slightly forward of this turbojet was mounted the de Havilland Spectre 1A or 3B (references differ) rocket engine of, respectively-7,000 lbft or 8,000 lbft fully-variable thrusts. The Spectre rocket used hydrogen peroxide (htp) as the oxidizer fuel with endurance at full power boost of seven minutes. Many design complexity setbacks to the development led to delay of the first scheduled flight in July 1954 with fleet introduction scheduled for 1957, including an explosion of the Spectre rocket motor during ground testing.
The rocket fuel also posed substantial maintenance/fueling concerns/problems projected to the squadron maintenance level, and only two prototypes of three contracted for were ever built, XD145 and XD151. XD145 first flew on 16 May 1957 piloted by Squadron Leader John Booth. That prototype may be seen preserved at the Royal Air Force Museum Cosford. The second prototype XD151, also flown by Booth crashed on 5 June 1958 during an aborted takeoff, killing John Booth. LtCdr Peter Lamb then took over the flight testing with the remaining XD145 aircraft.
The SR.53 with single pilot cockpit had a very narrow sleek fuselage with high dynamic Q, and only a small gun ranging radar and otherwise was intended to be directed by ground control radar to make interceptions. This small cross-section enabled high speeds with jet thrust/weight of 0.52. The lack of aircraft intercept radar would have relegated the SR.53 to simply a high-speed missile test platform. The SR.53 also was one of the few jets that had launcher rails on the aircraft's wingtips at the time, rather than under-wing missile-launcher rails. A flight test camera and instrumentation pod was sometimes mounted on the opposite-wing rail from the Firestreak AAM infra-red guided missile. The side airbrakes located just above the rocket engine were too effective originally and were subsequently perforated to let some airflow pass through.
As Rob pointed out-the loss of XD151 and John Booth in 1958 effectively axed the SR.53 program and its successor SR.177 planned interceptor with aircraft radar and higher endurance by the infamous Defence Review in 1957.
XD145 Specs/performance
Powerplant: One Armstrong-Siddeley A.S.V.8 Viper 101 turbojet of 1,640 lb thrust and one de Havilland Spectre 1A rocket engine of 7,000 lb thrust.
Thrust/Weight (jet) 0.52
Crew: One
Max speed: Mach 2.1 or 2.2
Rate of climb: 52,800 ft/min or time: 2 min 12 sec from brake release to 50,000'
Max Altitude: (projected) 130,000 ft (not a typo)
Service ceiling: 67,000 ft
Wingspan: 25'1"
Wing area: 274 sqft
Wing loading: 67.2 lb/sqft
Airfoil: RAE102
Length: 46'5"
Height: 10'10"
Weight: empty: 7,400 lb, loaded 18,400 lb
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As to the Skeeter two-seat helicopter also built by Saunders-Roe, they purchased the originator/builder of the Skeeter-Cierva Autogyro Company in 1951. Power was one de Havilland Gipsy Major of 200 or 215 hp. Operated by British Army and RAF, as well as the Army and Navy of the German Federal Republic in various nomenclatures.
