ESDU 73026 details the method of presenting the complete performance of a helicopter in terms of a set of non-dimensional parameters. Using the technique@ derived through dimensional analysis and relying on the engine torquemeter for power measurement@ flight test results can be analysed to provide information on helicopter performance under conditions different from those for which the results were obtained. The use of the method for particular performance characteristics is explained and illustrated for hover in ESDU 73027 and for level flight in ESDU 74042.