A few months ago I was asked to deliver a lecture to the Royal United Services Institution on the Radio War. In the preamble to that lecture I explained that my treatment of the subject would not consist of a description of the various radio devices which were used in the late war for purposes of communication, early warning and air navigation, but rather of a treatise on the methods that were employed to deny to our enemies the use of their radio services. My lecture dealt mainly, therefore, with the use of radio as a weapon; and the tactics that we evolved to exploit its employment for such a purpose not only in the defence of this country, but also in the protection of our bomber forces when attacking targets in enemy territory.

An analytical method is developed for calculating the speed and climb performance of jet-propelled aircraft, given the drag and thrust data. A method is also given for dealing with the effects of compressibility and the results in a typical example are included to illustrate the form of curves obtained.

In the past, when dealing with aircraft driven by reciprocating i-c engines and propellers it has not been possible, even on the assumption of the available power being independent of forward speed, to evolve an analytical method of calculating the complete level speed and rate-of-climb performance of the aircraft, because the level speed equation is a cubic, for which there is no general solution, while even a constant speed propeller causes the thrust horse power in the region of the best climbing speed to vary with forward speed in some manner that cannot be expressed as a simple function.