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KBBS Archive 00,000
Re: Please describe control cables
Posted By: Mark Kanzler In Response To: Re: Please describe control cables (Tom Scheibe)
Date: Thursday, 27 August 1998, at 6:55 p.m.
I'm going to nit pick here. A golfball uses the dimples to create a turbulent boundary layer. A turbulent boundary layer is more robust than a laminar boundary layer. Laminar boundary layers have less drag, but are harder to maintain because they are very sensitive to tripping by small surface imerfections. Turbulent boundary layers tend to stay attached even when minor imperfections in the suface exist.
I should have started this lecture by pointing out that there are three primary types of flow: laminar, turbulent, and detached flow. Detachment is where the boundary layer separates from the surface, and it occurs earlier in laminar flows. As the flow detaches, drag goes up drastically. A turbulent boundary layer has more drag than laminar, but will remain attached longer than laminar flow. Sometimes laminar flow, when tripped, becomes a turbulent boundary layer (a smoother transition). But, often a laminar flow will detach before becoming a turbulent boundary layer.
Introduction to Flight by John D. Anderson Jr. explains these phenomena in easy to understand language. I highly recommend the book, but being a textbook, it's expensive. The principles apply to hydrodynamics in almost all cases.
> even though they may be
> producing some kind of turbulence, may even have increased laminar flow.
> (the golf ball metaphor)> Anyway, loath to trust my verbal description, here is a diagram.
> Tom
Introduction to Flight by John D. Anderson
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KBBS Archive 00,000 is maintained by Nick Schade - Guillemot Kayaks with WebBBS 5.12.
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