IHS ESDU Non-dimensional methods for the measurement of level-flight performance of turbine-engined helicopters. 74042

ESDU 74042 shows how the method of ESDU 73026 is applied to analyse flight test measured data on level-flight performance. Three possible techniques are available. If rotor speed cannot be varied, Mach number effects are ignored and only density is required to characterise the atmosphere; otherwise temperature and either pressure or density must be measured. Collective pitch can be measured instead of using the torquemeter to measure power. A complete worked example based on practical test data illustrates the method. ESDU 73027 shows the method of ESDU 73026 applied to analyse hover flight-measured performance.