Actually, lift only comes into play when the ball is spinning. The reason a golf ball flies farther with dimples is because a golf ball is not aerodynamic. The air traveling around a smooth golf ball is traveling very fast close to the surface of the ball and the air will separate abruptly past the vertical center of the ball creating a large air void at the rear of the ball of drag slowing the ball down. The dimples are added to create turbulence near the surface of the ball allowing the air to decelerate around the ball so the air can follow the contour of the ball longer, reducing the cone of drag behind it.
A smooth surface will be faster than a rough surface if the air is able to follow the contour of the surface. Once the air cannot follow the surface, a result of speed and shape, then creating a turbulent surface will be beneficial. You get more surface drag from a rough surface but you can reduce the pressure drag trailing the object that is much greater drag. A rough suface creates turbulence and decelerates air around the boundary layer delaying it's separation from the object, reducing it's trailing drag. Jim -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf Of Mark Jones Sent: Thursday, April 13, 2006 7:09 AM To: KRnet Subject: Re: KR> Armoural The dimples on a golf ball are there for the purpose of lift which keeps the ball in the air longer. At least this is what I have always read. A golf ball with no dimples simply will not travel nearly as far as a dimples one because it has no lift. Haven't you guys seen the dimpled leading edge tape you can get for wings and props? It gives the wings more lift at slow speeds which keeps the air from breaking off the wing pre stall. On the prop, it gives it more bite. At least that is what I read. Mark Jones (N886MJ) Wales, WI USA E-mail me at flyk...@wi.rr.com Visit my NEW KR-2S CorvAIRCRAFT web site at www.flykr2s.com ----- Original Message ----- From: "D F Lively" <riksh...@interl.net> To: "KRnet" <kr...@mylist.net> Sent: Thursday, April 13, 2006 7:02 AM Subject: Re: KR> Armoural > KRnetters: > > This sounds analogous to the reason golf balls are "Dimpled". > > Don Lively > ------------------------------------------------------------------------ > > "Hennie van Rooyen [HQP]" wrote: > > > Hi all, > > > > Just my 2 cents on this subject. There's a lot of info on the net on this so I'll not even try to elaborate. > > > > Air over air causes a lot less friction than air over metal, fiber glass or whatever. Therefore a very slight rough surface on i.e. a wing (pinholes) will produce less friction than a very smooth wing surface and therefore also higher top speed. > > > > You actually want dull surfaces for more speed as bright smooth surfaces are purely for appeal and not for speed. The air clings to the surface and this is the exact opposite of what you want. > > > > I'm convinced that if you take sandpaper and apply to your KR giving it a dull, non shiny surface (not nice to look at), you'll get the speed increase you're after. > > > > Regards, > > Hennie > > > > -----Original Message----- > > From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On > > Behalf Of Frank Ross > > Sent: Thursday, April 13, 2006 10:13 AM > > To: KRnet > > Subject: RE: KR> Armoural > > > > I know there aren't many things funnier than putting a good coat of Armor All on the seat of a dirt-bike right before a steep hill-climb and watching the rider try to stay on the seat... > > > > > > Brian Kraut <brian.kr...@engalt.com> wrote: Did you scrape an inch of bugs off the leading edge before you put that > > Armor All on? > > > > I do know that fiberglass gliders fly considerably better when they are > > clean and waxed, but they have a whole lot more wetted area than a KR and > > competition gliders likely have much more critical airfoils than the KR > > does. > > > > Brian Kraut > > Engineering Alternatives, Inc. > > www.engalt.com > > > > > > --------------------------------- > > How low will we go? Check out Yahoo! Messenger's low PC-to-Phone call rates. > > _______________________________________ > > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > > please see other KRnet info at http://www.krnet.org/info.html > > > > -------------------------------------------------------------------------- --------------- > > This e-mail is confidential and is for the addressee only. > > Please refer to http://www.kumbaresources.com/email-disclaimer for important disclaimers. > > -------------------------------------------------------------------------- --------------- > > > > _______________________________________ > > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > > please see other KRnet info at http://www.krnet.org/info.html > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
