This is the mock up for the Dowty Rotol Ram Air Turbine (RAT) for the Tornado F3 Air Defence Variant (ADV).
It was a 4 bladed, 12,000 rpm constant speed (by variable blade pitch) turbine driving a Vickers, 4,000 psig, constant HP, hydraulic pump.
The RAT auto deployed in flight and supplied emergency hydraulic power to control the aircraft in the event of a double engine flame out, considered possible, in one particular operating domain.
The RAT provided emergency flying control power while the aircraft partially descended and re-lit the engines.
Once relit and normal hydraulic restored, the RAT was auto retracted and the flight continued.