The front two nozzles, which are made of steel, are fed with air from the LP compressor, the rear nozzles, which are of Nimonic with hot (650 °C) jet exhaust.
The airflow split is about 60/40 front back.
It is critical that the nozzles rotate together.
This is achieved by using a pair of air motors fed from the HP (high pressure) compressor, in a fail over configuration, pairs of nozzles connected with  motorcycle chains.
The nozzles rotate over an angular range of 98.5 degrees.

The Pegasus was also the first turbofan engine to have the initial compressor fan, the zero stage, ahead of the front bearing.
This eliminated radial struts and the icing hazard they represent.
The front two nozzles, which are made of steel, are fed with air from the LP compressor, the rear nozzles, which are of Nimonic with hot (650 °C) jet exhaust. The airflow split is about 60/40 front back. It is critical that the nozzles rotate together. This is achieved by using a pair of air motors fed from the HP (high pressure) compressor, in a fail over configuration, pairs of nozzles connected with  motorcycle chains. The nozzles rotate over an angular range of 98.5 degrees.
The Pegasus was also the first turbofan engine to have the initial compressor fan, the zero stage, ahead of the front bearing. This eliminated radial struts and the icing hazard they represent.
Rolls-Royce Pegasus