Still‐Air Range in the Stratosphere: A Method of Rapid and Accurate Calculation for Jet‐propelled Aeroplanes Operating above the Tropopause

A method is given for calculating rapidly and accurately, by the use of charts (Figs. 1–3), the still‐air range performance of jet‐propelled aircraft operating completely above the tropopause. Simple rules arc also derived in Section 3 for estimating the effect of small changes in certain parameters for use when a design is largely stabilized. Table I summarizes these rules by showing percentage changes in all‐up weight, fuel weight, mean cruising height, etc., for a given percentage change in other parameters, keeping certain other quantities constant. Appendix I shows the error involved by using an approximate rather than the accurate formula for estimating range. (See Section 3.) For simplification, the mean cruising height (defined as the height at which the aircraft weight is a mean between that at the beginning and that at the end of the cruising flight) is calculated, rather than the height over the target (i.e. half range height). Appendix II discusses the difference between the two heights. A typical range performance problem is worked out in Appendix III showing how the tables and charts arc used. Appendix IV gives some useful properties of that part of the I.C.A.N. standard atmosphere extending from the tropopause to 70,000 ft.