Rolls-Royce Tay

Rolls-Royce Tay

Tay is the name of two jet engines from the British manufacturer Rolls-Royce .

First Rolls-Royce Tay based on the Nene engine

The first engine called Tay (Rolls-Royce RB.44), a turbojet , was based on the Rolls-Royce Nene and was used during the 1950s. Basically it is a Nene engine that has been equipped with an afterburner. A license was sold to Pratt & Whitney and the engine was used as the Pratt & Whitney J48 in the Grumman F9F Panther and the Lockheed F-94 . Another license went to Hispano-Suiza in France ( Bois-Colombes ), who marketed the engine as Hispano-Suiza Verdon . It was used in the Dassault Mystère IV. The nominal thrust was 27.8 kN.

Second Rolls-Royce Tay based on the Spey engine

The second Tay engine is based on the Rolls-Royce Spey and is a turbofan . It was first approved in 1986. The low-pressure components come from the Rolls-Royce RB211 . This enabled the bypass ratio to be increased to 3 compared to the Spey. It is or was used in the Gulfstream IV (Tay 611-8, 62 kN), the Fokker 70 (Tay 620, 62 kN) and Fokker 100 (Tay 620, 62 kN or Tay 650, 67 kN). There are also conversion kits for the Tay engine for the BAC 1-11 (Tay 650, 67 kN), Boeing 727 (Tay 651, 64 kN) and Douglas DC-9 (Tay 651, 64 kN). The engine is still in production. The latest version of the Tay 611-8 (Tay 611-8C) is equipped with an EEC . It is the only engine in this series that is not controlled hydro-mechanically, but with the help of the FADEC . It therefore has a modified fuel system.

The modernized version of the Tay 611-8 is the Tay 611-8C. It has an air mass flow rate of 416 lbs / sec and a thrust of 13,850 lbs at sea level. It is flat-rated up to ISA + 15 ° C. The by-pass ratio is 3.2: 1. Therefore, it is a turbo fan engine with a medium bypass ratio. The compressor comprises a single-stage fan, a three-stage low-pressure compressor and a 12-stage high-pressure compressor in an axial design. The compression ratio is 16: 1. The combustion chamber consists of ten flame tubes that are connected to one another by ignition tubes. It is followed by the two-stage high-pressure turbine and the three-stage low-pressure turbine. Only the first turbine stage and the guide vanes of the second stage are cooled. The turbine inlet temperature at take-off (full load) is 1390K. The fuel system is controlled by the EEC and consists of a low-pressure pump, a high-pressure pump, the Fuel-Cooled-Oil-Cooler (FCOC) and the Fuel-Metering-Unit (FMU). The start system consists of a turbine air starter that is mounted on the external gearbox and works with 28PSI compressed air. The EEC takes over the control of the starting process. It regulates the amount of starting air via the starter air valve (SAV). The curb weight of this engine is 3390 lbs. The largest housing diameter is 48.8 ". The fan diameter is 44.8" and the length from nose cone to exhaust cone is 102 ". The engine is equipped with a hydraulically confirmed thrust reverser (TRU), which is electronically controlled by the EEC The thrust delivered during cruise is 1900 lbs at 43,000 ft and a speed of Mach 0.8. The SFC (specific fuel consumption) under these conditions is 0.707 lbs / hr / lbs. The direction of rotation of the shaft is opposite when viewed from the rear clockwise (CCW).

The Tay engine has seven main bearings. Ball bearings are used to absorb thrust. In order to be able to store both shafts, there are two ball bearings in the diffuser case. The remaining five bearings are roller bearings. They are suitable for holding the high-pressure and low-pressure turbines as they can compensate for thermal expansion.

The engine is divided into seven modules. Module 01 comprises the fan equipped with 22 blades. This is followed by module 02, the three-stage low-pressure compressor. Module 03 designates the high pressure compressor. Module 04 corresponds to the combustion chamber and high pressure turbine. The low-pressure turbine is referred to as module 05. Module 06 is the gear section for assemblies, module 07 the intermediate housing.

Technical specifications

	Tay 611-8	Tay 650
thrust	62 kN	67 kN
Bypass ratio	3.04: 1	3.06: 1
Pressure ratio	15.8: 1	16.2: 1
length	2405 mm	2405 mm
diameter	1118 mm	1138 mm
Empty weight	1339 kg / 3390 lbs	1515 kg / 3516 lbs
Compressor LP stages	3 + 1 fan	3 + 1 fan
Compressor HD levels	12	12
Turbine LP stages	3	3
Turbine HD stages	2	2
Combustion chambers	10	10

Web links

• EASA-TCDS-E.063 (PDF; 69 kB) - Type certification of the "Tay" series
• 88-GT-302 (PDF; 69 kB) - ASME paper on the development of the "Tay" engine