Due to increasing concerns on the environmental impact of aviation operations and rising fuel prices, there is renewed interest in propeller research. Although propellers can provide a step improvement in propulsive efficiency with respect to turbofan engines, they are generally associated with higher noise emissions. In this study, the effect of blade sweep on the trade-off between propeller efficiency and noise is investigated. A panel method was implemented to analyze the propeller aerodynamics, while a tonal far-field frequency formulation was used to analyze the propeller acoustics. It was concluded that the effect of blade sweep on the thickness noise for conventional propeller systems at a constant advance ratio is noticeable. A relation was found for the trade-off between propeller efficiency and noise. This relation shows that the sensitivity of noise reduction reduces as the maximum allowed efficiency penalty is increased. ... Read more