Lucas Aerospace GTS/APU Type CR201
The lucas Aerospace Gas Turbine Starter/Auxiliary Power Unit MKII, this unit is used to start the Pegasus engine in a Harrier aircraft and also to provide electrical power whilst it is on the ground. The CR201 is a development of the CT2023 unit built by Rotax and is in use today.

The lucas is a twin shaft gas turbine engine, a power turbine is used to provide starting torque and also to drive a generator. The engine is built in two halfs, a gas generator section drives the gas turbine accessories and a power output section turns over the Pegasus aircraft engine through a reduction gearbox. The power output section also incorporates a reduction gear, dog clutch mechanism, disc brake and power turbine governor. A 400 C/S 6 Kw alternator is also driven from the power turbine at 12,000 rpm.
The lucas has three modes of operation-
1. The power turbine drives a 400 Hz alternator and is controlled by a governor to maintain the speed and frequency.
2. The power turbine accelerates the Pegasus engine via the clutch and gearbox, meanwhile the gas generator is governed at a whooping 77,000 rpm. When the Pegasus starts the whole lot shuts down.
3. When already driving the generator and then required to start the aircraft, a disc brake first stops the turbine, a clutch then engages the drive to the engine. To reduce the load on the disc brake, the gas generator is reduced to an idle speed.
Lucas CR201 Specification
Power Output.........................................82 Bhp (Start) 6 Kw (APU)
RPM......................................................77,000 (Start Mode) 55,000 (APU Mode)
Compressor............................................Centrifugal Impeller
Combustion Chamber.............................Reverse Flow Annular with 5 burners
Compressor Turbine...............................Radial Inflow Impeller
Power Turbine.......................................Axial Flow with epicyclic reduction gear
Layout....................................................Twin shaft, over hung gas generator, power turbine 20:1 speed reduction
Starting...................................................Electric Motor
Ignition...................................................High Energy Ignitor
Fuel System...........................................Gear Pump with Centrifugal Governor, Idle Control and Power Turbine Governor
Lubrication.............................................Dry Sump, shares oil tank with Pegasus
Application............................................Harrier Aircraft, replaces Rotax CT2023
Lucas GTS Flow Diagram
Lucas CR201 Mounted as a Stationary Engine
Instrument Panel

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