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Jabiru Cowls, Wing tips

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budyerly(at)msn.com
Guest

Posted: Fri Apr 17, 2009 2:18 pm Post subject: Jabiru Cowls, Wing tips

Not to butt in C  but as you all know C I have flaws...

 Wing tip design is to control vortices as we all know.  Mr. Dykins did a great job of designing the wing with the tip creating virtually no lift at cruise speeds of 130 KTS and up to 10 C000 MSL.  Therefore C in my opinion C an aerodynamic gimmick to reduce tip drag is not necessary C unless for cosmetics or utilty.  

 For those of you unfamiliar C the Europa wing lift distribution is very nearly elliptic (optimum) C giving the least induced drag at low altitude cruise.  Wing tip redesign is only necessary if the wing loading or wing lift distribution is not elliptic and a large vortex is generated by the wing tip C adding drag.  Horner tips or winglets work when the big square wing has a large vortex created at the tip due to lack of twist C so the added frontal area drag is compensated for by the reduced vortex drag.  And frankly C the increase in wing area at the tip reduces the stall speed C not the shape in GA aircraft.  On large aircraft with swept wings C winglets help break down tip drag and tip losses due to the wide flight envelope of the aircraft.

 Should we ask our Europa wing design to lift another 500 pounds of airplane C or cruise above 20 C000 MSL C wing tip design may be relevant.  I like what Claude Tugwell did on his classic.  He made the tip to include a slight Horner dip adding about 6 inches from aileron end to the tip.  It makes grasping the tip for carrying C rigging and de-rigging easier C but doesn't do a thing for speed.

 A Plane Jane wing tip isn't sexy C but it works if the wing design is right.  As one of my aerodynamics instructors (Mr. Bonde C who worked on the original 727 wing) said in college C  "Tip design can be a flat plate if you got the lift distribution right".

 We'll talk more at Sun n Fun over a bit of libation.

 Now I have to get the displays ready for Sun 'n Fun.

 Bud Yerly

 Custom Flight Creations (813) 653-4989

 	  Quote: 	
		   Date: Fri C 17 Apr 2009 19:35:19 +0200

 From: frans(at)paardnatuurlijk.nl

 To: europa-list(at)matronics.com

 Subject: Re: Europa-List: Re: Jabiru Cowls

 --> Europa-List message posted by: Frans Veldman <frans(at)paardnatuurlijk.nl>

 Graham Singleton wrote:

 > I used to try and get Don (and Ivan) to explore wing tip design but he

 > never would C he felt that in the cruise the induced drag was so low

 > (because of the wing area) that it wasn't worth the troublel; probably

 > true for the cruise but not true for climb.

 I recall having read somewhere that for the speeds reached by

 GA-aircraft C any improvements by winglets etc. is countered by the

 additional drag (frontal area C friction drag). If you see winglets C it

 is usually the result of fashion C not science.

&gt Archive Search & Download C 7-Day Browse C Chat C FAQ C

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