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Snarler
Type	Rocket engine
National origin	United Kingdom
Manufacturer	Armstrong Siddeley
Major applications	Hawker P.1072

The Armstrong Siddeley Snarler was a small rocket engine used for mixed-power experiments with an early turbojet engine.^[1]^[2] and was the first British liquid-fuelled rocket engine to fly.^[3]

Design and development

Unlike other British rocket engine projects that used hydrogen peroxide as an oxidiser, Armstrong Siddeley's used liquid oxygen. The rocket engine is described as having a dry weight of 215 lbf (960 N) thrust of 2,000 lbf (8.9 kN) and a specific fuel consumption of 20 (lb/h)/lbf thrust.^[3] Work began in 1947 and the final configuration was first tested on 29 March 1950.^[3]

The prototype of the Hawker P.1040 Sea Hawk, VP 401, had a Snarler rocket of 2,000 lbf thrust added in its tail. The Rolls-Royce Nene turbojet, of 5,200 lbf thrust, had a split tailpipe which exhausted either side of the fuselage. The combination was termed the Hawker P.1072.^[4]^[5]

This gave approximately^[6] 50% greater thrust, although with twenty times the fuel consumption.^[3] It was first used in flight on 20 November 1950, by Hawker's test pilot Trevor "Wimpy" Wade.^[4] Half a dozen flights were made using the rocket motor before a minor explosion damaged the aircraft. Although methanol was used in the P.1072, jet fuel could be used for the Snarler. It was decided that reheat was a more practical proposition for boosting jet thrust than rockets.

An unusual feature of the engine was that the fuel/oxidiser pump was externally driven, by a drive from the gearbox of the P.1072's turbojet engine. This feature continued into the first versions of the subsequent Screamer engine, but was later replaced with a turbine-driven turbopump.^[7]

Variants

ASSn.1 Snarler: The prototype and test engines, (Ministry of Supply designation ASSn.).

Applications

Hawker P.1072

Specifications

Data from Aircraft engines of the World 1953,^[8] Flight:6 August 1954:Armstrong Siddeley Snarler^[9]

General characteristics

Type: rocket engine booster
Length: 94 in (2,400 mm) (overall length); 25.4 in (650 mm) (combustion chamber length)
Diameter: 12.5 in (320 mm) (nozzle diameter)
Dry weight: 215 lb (98 kg)
Propellant capacity: 120 imp gal (140 US gal; 550 L) fuel; 75 imp gal (90 US gal; 340 L) oxidiser
Fuel: 65% methanol, 35% water
Oxidiser: liquid oxygen

Components

Pumps: externally driven accessory gearbox mounted centrifugal pumps with de-aerators

Performance

Thrust: 1,350–2,350 lbf (6.0–10.5 kN) at 20,000 ft (6,100 m) (dependent on main engine speed)
Part thrust: 450–750 lbf (2.0–3.3 kN) at 20,000 ft (6,100 m) (dependent on main engine speed)
Burn time:
Thrust-to-weight ratio: 6.28–10.93 (part thrust: 2.09–3.49)
Specific impulse: 195 seconds (1.91 km/s)
Burn time: 2 minutes 45 seconds (Hawker P.1072 installation)
Thrust specific fuel consumption: 20 lb/(lbf⋅h) (570 g/(kN⋅s))

References

^ S. Allen (7 December 1951). "Rockets for Aircraft Propulsion". The Aeroplane.
^ "Snarler: Armstrong Siddeleys Oxygen Water-methanol Rocket Motor : Handling Liquid Oxygen". Flight: 92–93. 25 July 1952.
^ ^a ^b ^c ^d "Aero engines 1954". Flight: 447–448. 6 August 1954.
^ ^a ^b "Armstrong Siddeley Snarler". Flight: 92–93. 25 July 1952.
^ "The Quest for Power..." Flight: 444. 6 August 1954. Transferring liquid oxygen from a B.O.C. spherical tanker to the Hawker P.1072 in which the Sn rocket was tested. The gas is exhausting through the lower vents and rapidly evaporating.
^ Although the Nene's thrust, as for any turbojet, fell with increasing altitude the Snarler's remained constant.
^ "Armstrong Siddeley Screamer". Flight: 160–164. 27 July 1956.
^ Wilkinson, Paul H. (1953). Aircraft engines of the World 1953 (11th ed.). London: Sir Isaac Pitman & Sons Ltd.
^ "Armstrong Siddeley Snarler:THE DEVELOPMENT OF A PUMP-FED LIQUID-FUEL AIRCRAFT ROCKET". Flight. 66 (2376): 176–180. 6 August 1954. Retrieved 7 January 2019.