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Old 09-16-2014, 09:56 AM   #432
Art
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City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
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Quote:
Originally Posted by manyboats View Post
Peter,
Perhaps my word "interplane drag" wasn't the best ... got this on a web search.

"The Pander E showing its sesquiplane configuration in flight
Variations on the biplane concept include the sesquiplane, where one wing (usually the lower) is significantly smaller than the other either in span, chord or both. The name means "one-and-a-half wings." The arrangement reduces interference drag between the wings whilst retaining some of the biplane's structural advantage. The 1920s Pander E is an example of an aircraft with a lower wing of exactly half the span and nearly one quarter (23%) of the area of the upper one. Some designs keep the upper and lower spans nearly equal for structural optimization, whilst reducing the lower chord, allowing near vertical interplane struts; probably the best known examples are the Nieuport military aircraft — from the Nieuport 10 through to the Nieuport 27, all designed by Gustave Delage during the Great War. The later Waco Custom Cabin series proved to be a popular example in general aviation."

They use the expression "interference drag" .... same thing. It's not even high tech much less deep science. It's a fact of physics.

Rex,
Thanks for the interesting discussion on the Excel. But just for holding power the concave fluke has the advantage. Just like airplanes the anhedral wing is more efficient but there are far more dihedral wings than anhedral. Stability ect ect just like the convex anchors there are compelling advantages to a convex fluke. But the greatest amount of effective surface area w the least amount of steel and weight is not convex or concave but flat. Many anchors could probably benefit from flat flukes.
e.g. - Fortress and Danforth

IMHO - Fortress' claim to fame that I believe supersedes/improves Danthforth's old-school design:

1. 45 degree shank to angle capability for better set in lose-mud bottom with standard 33 +/- degree capability also available for setting into other bottom surfaces, and;

2. Considerably lighter weight for handling while providing as much or better strength of material... with same or increased fluke sq. inch areas
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