Saunders-Roe SR.177

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Saunders-Roe SR.177

Description
Role	Interceptor project
Crew	one, pilot
First Flight	(never completed)
Designer	Saunders-Roe
Dimensions as designed
Length	50 ft	15.2 m
Wingspan	30 ft	9.1 m
Height	14 ft	4.3 m
Wing area	ft²	m²
Weights as designed
Empty	lb	kg
Loaded	25,500 lb	11,570 kg
Maximum takeoff	lb	kg
Intended powerplant
Jet engine	1 × de Havilland Gyron Junior
Thrust	8,000 lbf	35.6 kN
Rocket engine	1 × de Havilland Spectre
Thrust	8,000 lbf	35.6 kN
Anticipated performance
Maximum speed	1,550 mph	2,500 km/h
Combat range	miles	km
Ferry range	miles	km
Service ceiling	67,000 ft	20,500 m
Rate of climb	60,000 ft/min	18,300 m/min
Wing loading	lb/ft²	kg/m²
Thrust/Weight
Avionics
Avionics	A.1 radar
Armament
Missiles	2 × Fairey Firestreak missiles

The Saunders-Roe SR.177 was a 1950s project to develop a combined jet- and rocket-powered interceptor aircraft for the Royal Air Force and Royal Navy. The German Navy also expressed interest in the project, which was cancelled due to changes in Britain's military policies in 1957. An even larger variant was studied under the SR.187 project, but this work was also cancelled in 1957.

In 1952, Saunders-Roe had won a contract to develop a similar aircraft, the Saunders-Roe SR.53. However, as development progressed, the shortcomings of the design became increasingly evident. Most particularly, as with the German rocket-powered interceptors of World War II, the range and endurance of such an aircraft were limited by the high rate of fuel consumption by the rocket engine. However, as turbojets developed and became increasingly powerful and efficient, soon new powerplants were available that would make the aircraft more practical.

The SR.177 began as an advanced design concept for the SR.53, but when a development contract was issued by the Ministry of Defence (specification F.155), the project was given its own designation.

The most significant difference between the two aircraft was the use of a jet engine with nearly five times the thrust of the one chosen for the earlier aircraft. This meant that while the SR.53 relied mostly on its rocket engine for climbing, the SR.177 would be able to add considerable endurance by conserving use of its rocket only for a dash towards a target. It was expected that the added endurance would allow the SR.177 to perform roles other than pure interception, and these were expected to include strike and reconnaissance. The SR.53 design was considerably enlarged to accommodate the new engine, and the original sleek lines were forfeited for a large, chin mounted intake to supply it with air.

Funding was secured in July 1956 for a total of 27 aircraft, and the first was expected to fly by April (later, October) 1958. However, 1957 was to see a massive re-thinking of air defence philosophy in the UK, outlined in the 1957 Defence White Paper which called for piloted warplanes to be replaced by missiles. By the time that the programme was axed later that year, the aircraft had proceeded little past mock-up stage.

Work on the aircraft continued a little longer, however, in the anticipation of continued interest from Germany. The British Ministry of Supply agreed to continue funding development of five of the six prototypes, but nothing was to come of it. The German government had changed its priorities from looking for an interceptor to a strike fighter, leading Saunders-Roe to redesign the aircraft for this role. This was followed immediately by another redesign when Rolls-Royce successfully convinced the German government to replace the de Havilland engine intended for the SR.177 with a Rolls-Royce turbojet. Even with Heinkel preparing to manufacture the aircraft locally under licence, Germany withdrew support and eventually chose to purchase the F-104 Starfighter instead.