First run in 1953, the Rolls-Royce RB.106 was an advanced military turbojet engine by Rolls-Royce and was sponsored by the Ministry of Supply.
A two-shaft design with two axial flow compressors each driven by its own single stage turbine and reheat, it was of similar size to the Rolls-Royce Avon, allowing it to be used as a drop-in replacement, but it would have produced about twice the thrust at 21,750 lbf (96.7 kN). The two-shaft layout was relatively advanced for the era; the single-shaft de Havilland Gyron matched it in power terms, while the two-spool Bristol Olympus was much less powerful at the then-current state of development.
A scaled-up version of the RB106 intended for F.155 was the Rolls-Royce RB122. The RB.106 project was cancelled in March 1957, at a reported total cost of £ 100,000.