title: Allison J71
text: # Allison J71
  
  The Allison J71 was a single spool turbojet engine, designed and built in the United States. It began development in 1948 as a much modified J35, originally designated J35-A-23.
  
  ## Operational history
  
  The Allison J71 turbojet powered the Douglas B-66 Destroyer and the McDonnell F3H-2 Demon after the failed Westinghouse J40 proved unworkable. The prototype P6M SeaMasters were also fitted with the engine.
  
  ## Variants
  
  Data from: Aircraft engines of the World 1953
  
  ### J71-A-2
  
      Powered the McDonnell F3H Demon
  
  ### J71-A-2E
  
      9,700 lbf (43.15 kN) thrust (14,000 lbf (62.28 kN) thrust with afterburner), for the McDonnell F3H-2 Demon.
  
  ### YJ71-A-3
  
      7,000 lbf (31.14 kN) thrust (9,500 lbf (42.26 kN) thrust with afterburner)
  
  ### J71-A-4
  
      Afterburning turbojet engines for the Martin XP6M-1 Seamaster flying boat prototypes.
  
  ### J71-A-6
  
      Afterburning turbojet engines for the Martin YP6M-1 Seamaster pre-production flying boats.
  
  ### J71-A-7
  
      14,000 lbf (62.28 kN) thrust with afterburner
  
  ### J71-A-9
  
      Powered the Douglas RB-66 Destroyer
  
  ### J71-A-11
  
      10,200 lbf (45.37 kN) thrust
  
  ## Specifications (Allison J71-A-2)
  
  Data from Aircraft engines of the World 1957
  
  **General characteristics**
  
  * Type: afterburning turbojet
  * Length: 284.5 in (7,230 mm)
  * Diameter: 39.5 in (1,000 mm)
  * Frontal area: 8.5 sq ft (0.79 $m^2)$
  * Dry weight: 4,890 lb (2,220 kg)
  
  **Components**
  
  * Compressor: 16-stage axial compressor
  * Combustors: cannular with 10 flame tubes
  * Turbine: 3-stage axial
  * Fuel type: JP-4 / aviation kerosene
  * Oil system: pressure spray with scavenge at 10–60 psi (69–414 kPa)
  
  **Performance**
  
  * Maximum thrust: take-off, dry 10,000 lbf (44,000 N); take-off, wet 14,000 lbf (62.28 kN)
  * Overall pressure ratio: 8.0:1
  * Air mass flow: 160 lb/s (73 kg/s) at 6,100 rpm (static)
  * Specific fuel consumption: 1.8 lb/(lbf⋅h) (51 g/(kN⋅s)) with afterburner (wet)
  * Thrust-to-weight ratio: 2.857
  