Humpback Flippers and Traditional Sails?

[alkorn]

Recent news stories have told how researchers found that the bumps on the leading edge of a humpback whale's flipper improve its hydrodynamic performance.
http://www.sciencenewsforkids.org/articles/20040915/a520_4644.jpg
This figure from the paper by Miklosovic, Murray, Howle, and Fish shows that an test airfoil with bumps (plotted triangles) shows significantly better stall characteristics than a smooth airfoil (plotted lines):
http://www.filebox.vt.edu/users/alkorn/flipper.jpg
Could it be that the bumps on the leading edge of traditional sails - from lacing or mast hoops - actually improve airfoil performance?

I'd like to hear your thoughts on this.

[paladin]

"Cuffs" or similar bumps on the leading edge of aircraft wings have been used to improve the low speed flight characteristics of aircraft for decades. Some experiments dating back to the 1930's, Stinson Aircraft for example, used stall slats to improve airflow at high angles of attack. Globe/TEMCO who built the Swift used similar slats. The Helio Stallion and Pilatus Porter that I flew in Asia had these installed to allow slow flight below the normal landing or stall speed of the aircraft. Any STOL modifications to allow slow flight virtually always involve modifying the leading edge of the wing, gap seals on control surfaces to redirect airflow, and wing fences and tip extensions and cuffs to improve the low speed lift characteristics....the same things may be supplied to underwater foils for similar reasons.

[johnw]

Bumps on the mast were tried on an America's Cup boat in the late '60s or early '70s, but they didn't catch on. You get lots of turbulence around a mast if you don't have sleeved sails anyhow, so maybe turbulence generators are redundant.