Momentum theory supplied a mathematical model of the ideal propeller through work associated with W. J. M. Rankine, A. G. Greenhill, and R. E. Froude. Idealized results alone could not explain the control and thrust obtained from physical blades. Blade-element theory therefore examined how individual blade sections interact with the surrounding water and why a mathematically attractive helix can disappoint in service. Work by William Froude, Stefan Drzewiecki, and D. W. Taylor helped connect theory to practical design, including the efficiency demands of early submarines.
Chapter · 15:39-19:09
Momentum theory and blade-element theory in propeller design
Late-nineteenth-century theory explains both the ideal thrust of a propeller and why real blades moving through water depart from that ideal.