A review of the problem of choosing a climb technique, with proposals for a new climb technique for high performance aircraft

Abstract

The climb techniques at present used on modern aircraft entail quite high true air speeds and high kinetic energies. It was desired to investigate the effect of kinetic energy variation with height, which is ignored in present methods, on the choice of climb technique. The problem of choosing the best climbing technique is considered and the limitations of the present technique discussed. A new approach is made to the general problem of choosing the best climb technique between any specified end conditions, and with the aid of a geometrical illustration tentative conclusions are deduced concerning the choice of climb technique. These are presented for discussion prior to a fuller investigation. It is concluded that the application of present methods of choosing a climb technique to aircraft whose speeds on the climb are high is open to question. Introduction of 'energy height' as a variable permits a more exact treatment to be attempted and enables a geometrical illustration to be developed of the general problem of optimum climb between specified end conditions. From discussion of this illustration it is tentatively concluded that a revised climb technique, outlined in the Report, will give improved performance by building up a relatively high kinetic energy at low altitudes, where the thrust available is high, for conversion into potential energy (i.e. height) at high altitudes. In a particular example the new technique reduced the times required to climb to 40,000 ft and 45,000 ft by 1.4 minutes (9 per cent) and 2-5 minutes (10 per cent) respectively. It is hoped to investigate the proposed technique experimentally with a view to confirming its superiority over present methods.