Multi-component blade load measurements on a propeller in ice

Two highly skewed controllable pitch model propellers were tested in both open water and ice covered water in an ice tank. Both propellers had the same skew and root angle of attack but were manufactured with two different pitch distributions. The open water and ice experiments were both done at four different pitch settings, each over a range of advance coefficients. The ice strength and the depth cut into the ice by the propeller were varied in the tests. The main aims of the experiments were to measure the effects of these variables on blade loads, in addition to their effects on shaft loads, and to compare the effect of pitch distribution on these. Shaft loads were measured using conventional dynamometry. Loads on one blade were measured using a six component hub-mounted blade dynamometer designed and built for these tests. The blade dynamometer is described and shaft and blade load measurements are presented and discussed. It was discovered that in certain conditions the individual blade experienced bending moments, thrust and torque loads that were on the order of ten times the mean cycle load during the ice milling event.