MUCH of the continuing growth and versatility of civil and military air transport is due to advances in the aeronautical gas turbine. This process is still going on and the prediction that the number of passengers traveling by air will double by the year 2000 underlines these developments. A company at the forefront in this field is Rolls‐Royce whose policy of derivative designs from proven concepts with the incorporation of the most up‐to‐date technology is leading to the achievement of high levels of efficiency and reliability.