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Rolls-Royce RB.44 Tay
Hispano-Suiza Verdon
Hispano-Suiza Tay
Pratt & Whitney J48 / JT7



The Tay was developed in the first instance by Rolls-Royce from the basic Nene design. Two units of the type were test-flown in a special Vickers Viscount. It has been further improved by the Pratt and Whitney and HispanoSuiza concerns, which, respectively, hold the American and French licences. In America the engine is known as the J48, and its applications include the Lockheed F-94C Starfire, Grumman F9F-5 Panther and F9F-6 Cougar. Ratings of 6,250-7,000 lb have been recorded without water injection, a power-boost system which increases thrust by about 1,000 lb.


By 1948, Rolls-Royce had designed the Tay turbojet, also a centrifugal-flow design. However, as Rolls-Royce was then developing an improved design with an axial compressor, which would become the Avon, the development and production of the Tay turbojet was left to Pratt & Whitney. However, Rolls-Royce retained the rights to the Tay outside of the United States.

A total of 4,108 were built.

The Tay/J48 was a thirty percent enlargement of the preceding Nene/J42, and was produced both with and without afterburning.


Pratt & Whitney J48


Hispano-Suiza Tays have been installed in Dassault Mystere II, III and IV fighters, and the Tay 250 is for the Mystere IVA. A development of the Tay by the French company is called the Verdon (following the "River" nomenclature) and has a modified compressor with new guide-vanes, revised flame-tubes and combustion chambers, and new turbine-blades and disc. A special afterburner has been developed for this engine, which is to replace the Tay in the Mystere IVA.


Hispano-Suiza Verdon


The new J48 in 1950 powering the North American YF-93A developed 6250 lb thrust, with another 1750 lb with afterburner. It was also planned to power the Navy’s new F9F-5 Panther.
1950 J-48



RB.44 Tay
Rolls-Royce development engines only, no production.


Hispano-Suiza Verdon
The Tay built and developed under licence in France.


Pratt & Whitney J48
The Tay built and developed under licience in the United States.
J48-P-1: 6,000 lbf (26.7 kN), 8,000 lbf (35.6 kN) thrust with afterburning
J48-P-2: 6,250 lbf (27.8 kN), 7,000 lbf (31.1 kN) thrust with water injection
J48-P-3: 6,000 lbf (26.7 kN), 8,000 lbf (35.6 kN) thrust with afterburning
J48-P-5: 6,350 lbf (28.2 kN), 8,750 lbf (38.9 kN) thrust with afterburning
J48-P-6: 6,250 lbf (27.8 kN), 7,000 lbf (31.1 kN) thrust with water injection
J48-P-7: 6,350 lbf (28.2 kN), 8,750 lbf (38.9 kN) thrust with afterburning
J48-P-8: 7,250 lbf (32.2 kN) thrust
J48-P-8A: 7,250 lbf (32.2 kN) thrust



Vickers 663 Tay Viscount

Dassault Mystère IV

Grumman F9F-5 Panther
Grumman F9F-6/F9F-8 Cougar
Lockheed F-94C Starfire
North American YF-93




Pratt & Whitney J48-P-8A
Type: Turbojet
Length: 202 in (513 cm)
Diameter: 50 in (127 cm)
Dry weight: 2,101 lb (953 kg)
Compressor: Centrifugal compressor
Maximum thrust: 7,250 lbf (32.2 kN) thrust


Hispano-Suiza Verdon 350
Type: Turbojet
Length: 103.2 in (2,621 mm)
Diameter: 50 in (1,270 mm)
Dry weight: 2,061 lb (935 kg)
Compressor: Double sided centrifugal compressor
Combustors: Nine tubular combustion chambers
Turbine: Single-stage turbine
Fuel type: AVTUR / JET-A1 / F-34 etc.
Oil system: Pressure spray lubricated with scavenging
Maximum thrust: 7,710 lbf (34 kN) at 11,000 rpm
Overall pressure ratio: 4.9
Specific fuel consumption: 1.1 lb/lb/hr
Thrust-to-weight ratio: 3.74




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