Travellers by air to-day only too often can be heard to remark how good it is to be on the ground again. Even now flying is considered by many as an adventure and only those living near an airfield realise the regularity and reliability of air transport.

It is with the hope of removing this feeling of adventure and instilling a sense of security in air travel that this Paper has been written. An attempt has been made to reduce the power plant engineering to plain science and to show the care, knowledge and painstaking development that has gone into the design.

The second world war resulted in tremendous progress in aeronautics and while, during the war, the major factor was the aircraft efficiency as an offensive unit, that was not to say that reliability and passenger comfort were ignored.