Armstrong Siddeley Snarler

The Armstrong Siddeley ASSn. Snarler was a small rocket engine used for mixed-power experiments with an early turbojet engine.[2][3] and was the first British liquid-fuelled rocket engine to fly.[1] 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.[1] Work began in 1947 and the final configuration was first tested on 29 March 1950.[1]

ASSn.1 Snarler
Country of originUnited Kingdom
ManufacturerArmstrong Siddeley
Liquid-fuel engine
PropellantLiquid oxygen (LOX) / methanol/water
PumpsCentrifugal, mechanically driven by external shaft drive from other engine.
Thrust1,350–2,350 lbf (6.0–10.5 kN)[1]
Propellant capacityLOX 75 imperial gallons (340 L),
water-methanol 120 imperial gallons (550 L)[1]

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.[1] 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]


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


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


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


  • 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))


  1. "Aero engines 1954" (PDF). Flight: 447–448. 6 August 1954.
  2. S. Allen (7 December 1951). "Rockets for Aircraft Propulsion". The Aeroplane.
  3. "Snarler: Armstrong Siddeleys Oxygen Water-methanol Rocket Motor : Handling Liquid Oxygen" (PDF). Flight: 92–93. 25 July 1952.
  4. "Armstrong Siddeley Snarler" (PDF). Flight: 92–93. 25 July 1952.
  5. "The Quest for Power..." (PDF). 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.
  6. Although the Nene's thrust, as for any turbojet, fell with increasing altitude the Snarler's remained constant.
  7. "Armstrong Siddeley Screamer" (PDF). Flight: 160–164. 27 July 1956.
  8. Wilkinson, Paul H. (1953). Aircraft engines of the World 1953 (11th ed.). London: Sir Isaac Pitman & Sons Ltd.
  9. "Armstrong Siddeley Snarler:THE DEVELOPMENT OF A PUMP-FED LIQUID-FUEL AIRCRAFT ROCKET" (pdf). Flight. 66 (2376): 176–180. 6 August 1954. Retrieved 7 January 2019.
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