"A major source of helicopter drag, about 30% of the total, is from the rotor hub. It is important that the drag generated by a helicopter, and hence emissions, is reduced. This research programme is to be undertaken to investigate this subject and investigate potential techniques to achieve reductions in hub drag. A wind tunnel test programme is to be carried out to provide a large, high-quality experimental data set. A 5 bladed scale helicopter model is to be designed and manufactured. The model will be designed to enable the effect of model geometry to be examined by using a range of 5 rotor caps and 5 hub fairings. The overall model aerodynamic loads will be measured and the loads generated by the rotor hub and rotor cap will be independently obtained using internal load cell balances. Two Particle Image Velocimetry systems, 3D and time resolved, will be employed in parallel to acquire flow field data in regions of interest around the model. A range of representative flight conditions will be simulated. These acquired data will be processed to allow the significant features of the helicopters model’s aerodynamic characteristics to be obtained. This will expose the salient sources of rotor hub drag and so identify techniques that may be employed to reduce the magnitude of this force. The data will also be available for the development and validation of CFD codes."